MAMMALS are any vertebrates within the class MAMMALIA
(/məˈmeɪli.ə/ from Latin mamma "breast"), a clade of endothermic
amniotes distinguished from reptiles (including birds ) by the
possession of a neocortex (a region of the brain), hair , three middle
ear bones and mammary glands . Females of all mammal species nurse
their young with milk , secreted from the mammary glands.
Mammals include the biggest animals on the planet, the great whales .
The basic body type is a terrestrial quadruped , but some mammals are
adapted for life at sea , in the air , in trees , underground or on
two legs . The largest group of mammals, the placentals , have a
placenta , which enables the feeding of the fetus during gestation.
Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat
to the 30-meter (98 ft) blue whale . With the exception of the five
species of monotreme (egg-laying mammals), all modern mammals give
birth to live young. Most mammals, including the six most species-rich
orders , belong to the placental group. The largest orders are the
rodents , bats and
Soricomorpha (shrews and allies). The next three
biggest orders, depending on the biological classification scheme
used, are the
Primates (apes and monkeys ), the Cetartiodactyla
(whales and even-toed ungulates ), and the
Carnivora (cats , dogs ,
seals , and allies).
Living mammals are divided into the
Yinotheria (platypus and echidnas
Theriiformes (all other mammals). There are around 5450 species
of mammal, depending on which authority is cited. In some
classifications, extant mammals are divided into two subclasses: the
Prototheria , that is, the order Monotremata; and the Theria, or the
Eutheria . The marsupials constitute the
crown group of the Metatheria, and include all living metatherians as
well as many extinct ones; the placentals are the crown group of the
Eutheria. While mammal classification at the family level has been
relatively stable, several contending classifications regarding the
higher levels—subclass, infraclass and order, especially of the
marsupials—appear in contemporaneous literature. Much of the changes
reflect the advances of cladistic analysis and molecular genetics .
Findings from molecular genetics, for example, have prompted adopting
new groups, such as the
Afrotheria , and abandoning traditional
groups, such as the
The mammals represent the only living
Synapsida , which together with
Sauropsida form the
Amniota clade. The early synapsid mammalian
ancestors were sphenacodont pelycosaurs , a group that produced the
Dimetrodon . At the end of the
this group diverged from the sauropsid line that led to today's
reptiles and birds. The line following the stem group Sphenacodontia
split-off several diverse groups of non-mammalian
synapsids—sometimes referred to as mammal-like reptiles—before
giving rise to the proto-mammals (
Therapsida ) in the early Mesozoic
era. The modern mammalian orders arose in the
Paleogene and Neogene
periods of the
Cenozoic era, after the extinction of non-avian
dinosaurs , and have been among the dominant terrestrial animal groups
from 66 million years ago to the present.
Some mammals are intelligent , with some possessing large brains,
self-awareness and tool use . Mammals can communicate and vocalize in
several different ways, including the production of ultrasound ,
scent-marking , alarm signals , singing , and echolocation . Mammals
can organize themselves into fission-fusion societies , harems , and
hierarchies , but can also be solitary and territorial . Most mammals
are polygynous , but some can be monogamous or polyandrous .
In human culture, domesticated mammals played a major role in the
Neolithic revolution , causing farming to replace hunting and
gathering , and leading to a major restructuring of human societies
with the first civilizations . They provided, and continue to provide,
power for transport and agriculture, as well as various commodities
such as meat , dairy products , wool , and leather . Mammals are
hunted or raced for sport, and are used as model organisms in science.
Mammals have been depicted in art since
Palaeolithic times, and appear
in literature, film, mythology, and religion.
Defaunation of mammals
is primarily driven by anthropogenic factors, such as poaching and
habitat destruction , though there are efforts to combat this.
* 1 Classification
* 1.1 Definitions
* 1.2 McKenna/Bell classification
* 1.3 Molecular classification of placentals
* 2 Evolution
* 2.1 Origins
* 2.2 Evolution from amniotes
* 2.3 First mammals
* 2.4 Earliest appearances of features
* 2.5 Rise of the mammals
* 3 Anatomy and morphology
* 3.1 Distinguishing features
* 3.2 Biological systems
* 3.3 Sound production
* 3.5 Reproductive system
* 3.8 Locomotion
* 3.8.1 Terrestrial
* 3.8.3 Aerial
* 3.8.5 Aquatic
* 4 Behavior
* 4.1 Communication and vocalization
* 4.2 Feeding
* 4.4 Social structure
* 5 Humans and other mammals
* 5.1 In human culture
* 5.2 Uses and importance
* 5.3 Hybrids
* 5.4 Threats
* 6 Notes
* 7 See also
* 8 References
* 9 Further reading
* 10 External links
Mammal classification See also: List of placental
List of monotremes and marsupials
List of monotremes and marsupials , and List of mammal
genera The orders Rodentia (blue),
Chiroptera (red) and
Soricomorpha (yellow) together comprise over 70% of mammal species.
Mammal classification has been through several iterations since Carl
Linnaeus initially defined the class. No classification system is
universally accepted; McKenna & Bell (1997) and Wilson
Soricomorpha : shrews , moles and solenodons . The next
three biggest orders, depending on the biological classification
scheme used, are the
Primates including the apes , monkeys and lemurs
Cetartiodactyla including whales and even-toed ungulates ; and
Carnivora which includes cats , dogs , weasels , bears , seals and
allies. According to
Species of the World , 5,416 species were
identified in 2006. These were grouped into 1,229 genera , 153
families and 29 orders. In 2008, the International Union for
Conservation of Nature (IUCN) completed a five-year Global Mammal
Assessment for its
IUCN Red List
IUCN Red List , which counted 5,488 species.
The word "mammal" is modern, from the scientific name Mammalia coined
Carl Linnaeus in 1758, derived from the Latin mamma ("teat, pap").
In an influential 1988 paper, Timothy Rowe defined Mammalia
phylogenetically as the crown group of mammals, the clade consisting
of the most recent common ancestor of living monotremes (echidnas and
platypuses ) and therian mammals (marsupials and placentals ) and all
descendants of that ancestor. Since this ancestor lived in the
Jurassic period, Rowe's definition excludes all animals from the
Triassic , despite the fact that
Triassic fossils in the
Haramiyida have been referred to the Mammalia since the mid-19th
century. If Mammalia is considered as the crown group, its origin can
be roughly dated as the first known appearance of animals more closely
related to some extant mammals than to others. Ambondro is more
closely related to monotremes than to therian mammals while
Amphitherium are more closely related to the therians;
as fossils of all three genera are dated about 167 million years ago
in the Middle
Jurassic , this is a reasonable estimate for the
appearance of the crown group.
T. S. Kemp has provided a more traditional definition: "synapsids
that possess a dentary –squamosal jaw articulation and occlusion
between upper and lower molars with a transverse component to the
movement" or, equivalently in Kemp's view, the clade originating with
the last common ancestor of
Sinoconodon and living mammals. The
earliest known synapsid satisfying Kemp's definitions is Tikitherium ,
dated 225 Ma, so the appearance of mammals in this broader sense can
be given this Late
In 1997, the mammals were comprehensively revised by Malcolm C.
McKenna and Susan K. Bell, which has resulted in the McKenna/Bell
classification. Their 1997 book, Classification of Mammals above the
Species Level, is a comprehensive work on the systematics,
relationships and occurrences of all mammal taxa, living and extinct,
down through the rank of genus, though molecular genetic data
challenge several of the higher level groupings. The authors worked
together as paleontologists at the American Museum of Natural History
, New York . McKenna inherited the project from Simpson and, with
Bell, constructed a completely updated hierarchical system, covering
living and extinct taxa that reflects the historical genealogy of
Extinct groups are represented by a dagger (†).
* SUBCLASS PROTOTHERIA : monotremes: echidnas and the platypus
* SUBCLASS THERIIFORMES : live-bearing mammals and their prehistoric
* Infraclass †
Allotheria : multituberculates
* Infraclass †
Eutriconodonta : eutriconodonts
Holotheria : modern live-bearing mammals and their
* Superlegion †
Theria : live-bearing mammals
Marsupialia : marsupials
Australidelphia : Australian marsupials and the monito
Ameridelphia : New World marsupials. Now considered
paraphyletic, with shrew opossums being closer to australidelphians.
Placentalia : placentals
Xenarthra : xenarthrans
Epitheria : epitheres
* Superorder †
* Grandorder Anagalida : lagomorphs , rodents and elephant shrews
Ferae : carnivorans , pangolins , †creodonts and
Lipotyphla : insectivorans
Archonta : bats , primates , colugos and treeshrews
Ungulata : ungulates
Tubulidentata incertae sedis : aardvark
Eparctocyona : †condylarths , whales and artiodactyls
* Mirorder †
Meridiungulata : South American ungulates
Altungulata : perissodactyls (odd-toed ungulates),
elephants , manatees and hyraxes
MOLECULAR CLASSIFICATION OF PLACENTALS
Molecular studies based on
DNA analysis have suggested new
relationships among mammal families over the last few years. Most of
these findings have been independently validated by retrotransposon
presence/absence data . Classification systems based on molecular
studies reveal three major groups or lineages of placental
Boreoeutheria —which diverged
Cretaceous . The relationships between these three lineages is
contentious, and all three possible different hypotheses have been
proposed with respect to which group is basal . These hypotheses are
Atlantogenata (basal Boreoeutheria),
Epitheria (basal Xenarthra) and
Exafroplacentalia (basal Afrotheria).
Boreoeutheria in turn contains
two major lineages—
Estimates for the divergence times between these three placental
groups range from 105 to 120 million years ago, depending on the type
DNA used (such as nuclear or mitochondrial ) and varying
interpretations of paleogeographic data.
The cladogram above is based on Tarver et al. (2016)
GROUP I: SUPERORDER AFROTHERIA
Macroscelidea : elephant shrews (Africa)
Afrosoricida : tenrecs and golden moles (Africa)
Tubulidentata : aardvark (Africa south of the Sahara)
Hyracoidea : hyraxes or dassies (Africa, Arabia)
Proboscidea : elephants (Africa, Southeast Asia)
Sirenia : dugong and manatees (cosmopolitan tropical)
GROUP II: SUPERORDER XENARTHRA
Pilosa : sloths and anteaters (neotropical)
Cingulata : armadillos and extinct relatives (Americas)
GROUP III: MAGNAORDER BOREOEUTHERIA
* SUPERORDER: EUARCHONTOGLIRES (SUPRAPRIMATES )
Scandentia : treeshrews (Southeast Asia).
Dermoptera : flying lemurs or colugos (Southeast Asia)
Primates : lemurs, bushbabies, monkeys, apes, humans
Lagomorpha : pikas , rabbits , hares (Eurasia, Africa,
* Order Rodentia : rodents (cosmopolitan)
* SUPERORDER: LAURASIATHERIA
Eulipotyphla : shrews, hedgehogs, moles, solenodons
Chiroptera : bats (cosmopolitan)
Pholidota : pangolins or scaly anteaters (Africa, South
Carnivora : carnivores (cosmopolitan), including cats and
Cetartiodactyla : cetaceans (whales, dolphins and porpoises)
and even-toed ungulates, including pigs , cattle , deer and giraffes
Perissodactyla : odd-toed ungulates, including horses ,
donkeys , zebras , tapirs and rhinoceroses
Evolution of mammals
Evolution of mammals
Synapsida , a clade that contains mammals and their extinct
relatives, originated during the Pennsylvanian subperiod , when they
split from reptilian and avian lineages.
Crown group mammals evolved
from earlier mammaliaforms during the Early
Jurassic . The cladogram
takes Mammalia to be the crown group.
EVOLUTION FROM AMNIOTES
The original synapsid skull structure contains one temporal
opening behind the orbitals , in a fairly low position on the skull
(lower right in this image). This opening might have assisted in
containing the jaw muscles of these organisms which could have
increased their biting strength.
The first fully terrestrial vertebrates were amniotes . Like their
amphibious tetrapod predecessors, they had lungs and limbs. Amniotic
eggs, however, have internal membranes that allow the developing
embryo to breathe but keep water in. Hence, amniotes can lay eggs on
dry land, while amphibians generally need to lay their eggs in water.
The first amniotes apparently arose in the Pennsylvanian subperiod of
Carboniferous . They descended from earlier reptiliomorph
amphibious tetrapods, which lived on land that was already inhabited
by insects and other invertebrates as well as ferns , mosses and other
plants. Within a few million years, two important amniote lineages
became distinct: the synapsids , which would later include the common
ancestor of the mammals; and the sauropsids , which now include
turtles , lizards , snakes , crocodilians , dinosaurs and birds .
Synapsids have a single hole (temporal fenestra ) low on each side of
the skull. One synapsid group, the pelycosaurs , included the largest
and fiercest animals of the early
Permian . Nonmammalian synapsids
are sometimes called "mammal-like reptiles".
Therapsids , a group of synapsids, descended from pelycosaurs in the
Middle Permian, about 265 million years ago, and became the dominant
land vertebrates. They differ from basal eupelycosaurs in several
features of the skull and jaws, including: larger skulls and incisors
which are equal in size in therapsids, but not for eupelycosaurs. The
therapsid lineage leading to mammals went through a series of stages,
beginning with animals that were very similar to their pelycosaur
ancestors and ending with probainognathian cynodonts , some of which
could easily be mistaken for mammals. Those stages were characterized
* The gradual development of a bony secondary palate .
* Progression towards an erect limb posture, which would increase
the animals' stamina by avoiding Carrier\'s constraint . But this
process was slow and erratic: for example, all herbivorous
nonmammaliaform therapsids retained sprawling limbs (some late forms
may have had semierect hind limbs);
Permian carnivorous therapsids had
sprawling forelimbs, and some late
Permian ones also had semisprawling
hindlimbs. In fact, modern monotremes still have semisprawling limbs.
* The dentary gradually became the main bone of the lower jaw which,
by the Triassic, progressed towards the fully mammalian jaw (the lower
consisting only of the dentary) and middle ear (which is constructed
by the bones that were previously used to construct the jaws of
Triassic extinction event about 252 million years ago,
which was a prolonged event due to the accumulation of several
extinction pulses, ended the dominance of carnivorous therapsids. In
the early Triassic, most medium to large land carnivore niches were
taken over by archosaurs which, over an extended period (35 million
years), came to include the crocodylomorphs , the pterosaurs and the
dinosaurs; however, large cynodonts like
traversodontids still occupied large sized carnivorous and herbivorous
niches respectively. By the Jurassic, the dinosaurs had come to
dominate the large terrestrial herbivore niches as well.
The first mammals (in Kemp's sense) appeared in the Late Triassic
epoch (about 225 million years ago), 40 million years after the first
therapsids. They expanded out of their nocturnal insectivore niche
from the mid-
Jurassic onwards; The
Castorocauda , for
example, had adaptations for swimming, digging and catching fish.
Most, if not all, are thought to have remained nocturnal (the
Nocturnal bottleneck ), accounting for much of the typical mammalian
traits. The majority of the mammal species that existed in the
Mesozoic Era were multituberculates, eutriconodonts and
spalacotheriids . The earliest known metatherian is
found in 125 million-year-old Early
Cretaceous shale in China's
Liaoning Province . The fossil is nearly complete and
includes tufts of fur and imprints of soft tissues. Restoration
Juramaia sinensis , the oldest known Eutherian (160 mya)
The oldest known fossil among the
Eutheria ("true beasts") is the
Juramaia sinensis , or "
Jurassic mother from China",
dated to 160 million years ago in the late Jurassic. A later
Eomaia , dated to 125 million years ago in the early
Cretaceous, possessed some features in common with the marsupials but
not with the placentals, evidence that these features were present in
the last common ancestor of the two groups but were later lost in the
placental lineage. In particular, the epipubic bones extend forwards
from the pelvis. These are not found in any modern placental, but they
are found in marsupials, monotremes, nontherian mammals and
Ukhaatherium , an early
Cretaceous animal in the eutherian order
Asioryctitheria . This also applies to the multituberculates. They
are apparently an ancestral feature, which subsequently disappeared in
the placental lineage. These epipubic bones seem to function by
stiffening the muscles during locomotion, reducing the amount of space
being presented, which placentals require to contain their fetus
during gestation periods. A narrow pelvic outlet indicates that the
young were very small at birth and therefore pregnancy was short, as
in modern marsupials. This suggests that the placenta was a later
The earliest known monotreme was
Teinolophos , which lived about 120
million years ago in Australia. Monotremes have some features which
may be inherited from the original amniotes such as the same orifice
to urinate, defecate and reproduce (cloaca ) – as lizards and birds
also do – and they lay eggs which are leathery and uncalcified.
EARLIEST APPEARANCES OF FEATURES
Hadrocodium, whose fossils date from approximately 195 million years
ago, in the early Jurassic, provides the first clear evidence of a jaw
joint formed solely by the squamosal and dentary bones; there is no
space in the jaw for the articular, a bone involved in the jaws of all
early synapsids. Foramina in the upper jaw are not
indicative of whiskers , as in the red tegu (
The earliest clear evidence of hair or fur is in fossils of
Megaconus , from 164 million years ago in the
mid-Jurassic. In the 1950s, it was suggested that the foramina
(passages) in the maxillae and premaxillae (bones in the front of the
upper jaw) of cynodonts were channels which supplied blood vessels and
nerves to vibrissae (whiskers ) and so were evidence of hair or fur;
it was soon pointed out, however, that foramina do not necessarily
show that an animal had vibrissae, as the modern lizard
foramina that are almost identical to those found in the nonmammalian
Thrinaxodon . Popular sources, nevertheless, continue to
attribute whiskers to Thrinaxodon. Studies on
suggest that non-mammalian synapsids of the epoch already had fur,
setting the evolution of hairs possibly as far back as dicynodonts .
When endothermy first appeared in the evolution of mammals is
uncertain, though it is generally agreed to have first evolved in
non-mammalian therapsids . Modern monotremes have lower body
temperatures and more variable metabolic rates than marsupials and
placentals, but there is evidence that some of their ancestors,
perhaps including ancestors of the therians, may have had body
temperatures like those of modern therians. Likewise, some modern
therians like afrotheres and xenarthrans have secondarily developed
lower body temperatures.
The evolution of erect limbs in mammals is incomplete — living and
fossil monotremes have sprawling limbs. The parasagittal
(nonsprawling) limb posture appeared sometime in the late
early Cretaceous; it is found in the eutherian
Eomaia and the
metatherian Sinodelphys, both dated to 125 million years ago.
Epipubic bones, a feature that strongly influenced the reproduction of
most mammal clades, are first found in
Tritylodontidae , suggesting
that it is a synapomorphy between them and mammaliformes . They are
omnipresent in non-placental mammaliformes, though
Erythrotherium appear to have lacked them.
It has been suggested that the original function of lactation (milk
production) was to keep eggs moist. Much of the argument is based on
monotremes, the egg-laying mammals.
RISE OF THE MAMMALS
Therian mammals took over the medium- to large-sized ecological
niches in the
Cenozoic , after the Cretaceous–
event approximately 66 million years ago emptied ecological space once
filled by non-avian dinosaurs and other groups of reptiles, as well as
various other mammal groups, and underwent an exponential increase in
body size (megafauna ). Then mammals diversified very quickly; both
birds and mammals show an exponential rise in diversity. For example,
the earliest known bat dates from about 50 million years ago, only 16
million years after the extinction of the dinosaurs.
Molecular phylogenetic studies initially suggested that most
placental orders diverged about 100 to 85 million years ago and that
modern families appeared in the period from the late
Miocene . However, no placental fossils have been found from
before the end of the Cretaceous. The earliest undisputed fossils of
placentals comes from the early
Paleocene , after the extinction of
the dinosaurs. In particular, scientists have identified an early
Paleocene animal named
Protungulatum donnae as one of the first
placental mammals. however it has been reclassified as a
non-placental eutherian. Recalibrations of genetic and morphological
diversity rates have suggested a Late
Cretaceous origin for
placentals, and a
Paleocene origin for most modern clades.
The earliest known ancestor of primates is
Archicebus achilles from
around 55 million years ago. This tiny primate weighed 20–30 grams
(0.7–1.1 ounce) and could fit within a human palm.
ANATOMY AND MORPHOLOGY
Living mammal species can be identified by the presence of sweat
glands , including those that are specialized to produce milk to
nourish their young. In classifying fossils, however, other features
must be used, since soft tissue glands and many other features are not
visible in fossils.
Many traits shared by all living mammals appeared among the earliest
members of the group:
* JAW JOINT - The dentary (the lower jaw bone, which carries the
teeth) and the squamosal (a small cranial bone) meet to form the
joint. In most gnathostomes , including early therapsids , the joint
consists of the articular (a small bone at the back of the lower jaw)
and quadrate (a small bone at the back of the upper jaw).
* MIDDLE EAR - In crown-group mammals, sound is carried from the
eardrum by a chain of three bones, the malleus , the incus and the
stapes . Ancestrally, the malleus and the incus are derived from the
articular and the quadrate bones that constituted the jaw joint of
* TOOTH REPLACEMENT -
Teeth are replaced once or (as in toothed
whales and murid rodents) not at all, rather than being replaced
continually throughout life.
* PRISMATIC ENAMEL - The enamel coating on the surface of a tooth
consists of prisms, solid, rod-like structures extending from the
dentin to the tooth's surface.
* OCCIPITAL CONDYLES - Two knobs at the base of the skull fit into
the topmost neck vertebra ; most other tetrapods , in contrast, have
only one such knob.
For the most part, these characteristics were not present in the
Triassic ancestors of the mammals. Nearly all mammaliaforms possess
an epipubic bone, the exception being modern placentals.
Biological system Raccoon lungs being inflated
The majority of mammals have seven cervical vertebrae (bones in the
neck), including bats , giraffes , whales and humans . The exceptions
are the manatee and the two-toed sloth , which have just six, and the
three-toed sloth which has nine cervical vertebrae. All mammalian
brains possess a neocortex , a brain region unique to mammals.
Placental mammals have a corpus callosum , unlike monotremes and
The lungs of mammals are spongy and honeycombed. Breathing is mainly
achieved with the diaphragm , which divides the thorax from the
abdominal cavity, forming a dome convex to the thorax. Contraction of
the diaphragm flattens the dome, increasing the volume of the lung
cavity. Air enters through the oral and nasal cavities, and travels
through the larynx, trachea and bronchi , and expands the alveoli .
Relaxing the diaphragm has the opposite effect, decreasing the volume
of the lung cavity, causing air to be pushed out of the lungs. During
exercise, the abdominal wall contracts , increasing pressure on the
diaphragm, which forces air out quicker and more forcefully. The rib
cage is able to expand and contract the chest cavity through the
action of other respiratory muscles. Consequently, air is sucked into
or expelled out of the lungs, always moving down its pressure
gradient. This type of lung is known as a bellows lung due to its
resemblance to blacksmith bellows .
The mammalian heart has four chambers, two upper atria , the
receiving chambers, and two lower ventricles , the discharging
chambers. The heart has four valves, which separate its chambers and
ensures blood flows in the correct direction through the heart
(preventing backflow). After gas exchange in the pulmonary capillaries
(blood vessels in the lungs), oxygen-rich blood returns to the left
atrium via one of the four pulmonary veins . Blood flows nearly
continuously back into the atrium, which acts as the receiving
chamber, and from here through an opening into the left ventricle.
Most blood flows passively into the heart while both the atria and
ventricles are relaxed, but toward the end of the ventricular
relaxation period , the left atrium will contract, pumping blood into
the ventricle. The heart also requires nutrients and oxygen found in
blood like other muscles, and is supplied via coronary arteries .
Didactic models of a mammalian heart
The integumentary system is made up of three layers: the outermost
epidermis , the dermis and the hypodermis . The epidermis is typically
10 to 30 cells thick; its main function is to provide a waterproof
layer. Its outermost cells are constantly lost; its bottommost cells
are constantly dividing and pushing upward. The middle layer, the
dermis, is 15 to 40 times thicker than the epidermis. The dermis is
made up of many components, such as bony structures and blood vessels.
The hypodermis is made up of adipose tissue , which stores lipids and
provides cushioning and insulation. The thickness of this layer varies
widely from species to species; :97 marine mammals require a thick
hypodermis (blubber ) for insulation, and right whales have the
thickest blubber at 20 inches (51 cm). Although other animals have
features such as whiskers, feathers , setae , or cilia that
superficially resemble it, no animals other than mammals have hair .
It is a definitive characteristic of the class. Though some mammals
have very little, careful examination reveals the characteristic,
often in obscure parts of their bodies. :61 The carnassials
(teeth in the very back of the mouth) of the insectivorous aardwolf
(left) vs. that of a gray wolf (right) which consumes large
Herbivores have developed a diverse range of physical structures to
facilitate the consumption of plant material . To break up intact
plant tissues, mammals have developed teeth structures that reflect
their feeding preferences. For instance, frugivores (animals that feed
primarily on fruit) and herbivores that feed on soft foliage have
low-crowned teeth specialized for grinding foliage and seeds . Grazing
animals that tend to eat hard, silica -rich grasses, have high-crowned
teeth, which are capable of grinding tough plant tissues and do not
wear down as quickly as low-crowned teeth. Most carnivorous mammals
have carnassialiforme teeth (of varying length depending on diet),
long canines and similar tooth replacement patterns.
The stomach of Artiodactyls is divided into four sections: the rumen
, the reticulum , the omasum and the abomasum (only ruminants have a
rumen). After the plant material is consumed, it is mixed with saliva
in the rumen and reticulum and separates into solid and liquid
material. The solids lump together to form a bolus (or cud ), and is
regurgitated. When the bolus enters the mouth, the fluid is squeezed
out with the tongue and swallowed again. Ingested food passes to the
rumen and reticulum where cellulytic microbes (bacteria , protozoa and
fungi ) produce cellulase , which is needed to break down the
cellulose in plants. Perissodactyls , in contrast to the ruminants,
store digested food that has left the stomach in an enlarged cecum ,
where it is fermented by bacteria.
Carnivora have a simple stomach
adapted to digest primarily meat, as compared to the elaborate
digestive systems of herbivorous animals, which are necessary to break
down tough, complex plant fibers. The caecum is either absent or short
and simple, and the large intestine is not sacculated or much wider
than the small intestine. Bovine kidney
The mammalian excretory system involves many components. Like most
other land animals, mammals are ureotelic , and convert ammonia into
urea , which is done by the liver as part of the urea cycle .
Bilirubin , a waste product derived from blood cells , is passed
through bile and urine with the help of enzymes excreted by the liver.
The passing of bilirubin via bile through the intestinal tract gives
mammalian feces a distinctive brown coloration. Distinctive features
of the mammalian kidney include the presence of the renal pelvis and
renal pyramids , and of a clearly distinguishable cortex and medulla ,
which is due to the presence of elongated loops of Henle . Only the
mammalian kidney has a bean shape, although there are some exceptions,
such as the multilobed reniculate kidneys of pinnipeds, cetaceans and
bears. Most adult placental mammals have no remaining trace of the
cloaca . In the embryo, the embryonic cloaca divides into a posterior
region that becomes part of the anus, and an anterior region that has
different fates depending on the sex of the individual: in females, it
develops into the vestibule that receives the urethra and vagina ,
while in males it forms the entirety of the penile urethra . However,
the tenrecs , golden moles , and some shrews retain a cloaca as
adults. In marsupials, the genital tract is separate from the anus,
but a trace of the original cloaca does remain externally.
Monotremes, which translates from Greek into "single hole", have a
A diagram of ultrasonic signals emitted by a bat, and the echo
from a nearby object
As in all other tetrapods, mammals have a larynx that can quickly
open and close to produce sounds, and a supralaryngeal vocal tract
which filters this sound. The lungs and surrounding musculature
provide the air stream and pressure required to phonate . The larynx
controls the pitch and volume of sound, but the strength the lungs
exert to exhale also contributes to volume. More primitive mammals,
such as the echidna, can only hiss, as sound is achieved solely
through exhaling through a partially close larynx. Other mammals
phonate using vocal folds , as opposed to the vocal cords seen in
birds and reptiles. The movement or tenseness of the vocal folds can
result in many sounds such as purring and screaming . Mammals can
change the position of the larynx, allowing them to breathe through
the nose while swallowing through the mouth, and to create both oral
and nasal sounds; nasal sounds, such as a dog whine, are generally
soft sounds, and oral sounds, such as a dog bark, are generally loud.
Some mammals have a large larynx and, thus, a low-pitched voice,
namely the hammer-headed bat (Hypsignathus monstrosus) where the
larynx can take up the entirety of the thoracic cavity while pushing
the lungs, heart, and trachea into the abdomen . Large vocal pads can
also lower the pitch, as in the low-pitched roars of big cats . The
production of infrasound is possible in some mammals such as the
African elephant (Loxodonta spp.) and baleen whales . Small mammals
with small larynxes have the ability to produced ultrasound , which
can be detected by modifications to the middle ear and cochlea .
Ultrasound is inaudible to birds and reptiles, which might have been
important during the Mesozoic, when birds and reptiles were the
dominant predators. This private channel is used by some rodents in,
for example, mother-to-pup communication, and by bats when
echolocating. Toothed whales also use echolocation, but, as opposed to
the vocal membrane that extends upward from the vocal folds, they have
a melon to manipulate sounds. Some mammals, namely the primates, have
air sacs attached to the larynx, which may function to increase the
volume of sound.
The vocal production system is controlled by the cranial nerve
nucleus in the brain, and supplied by the recurrent laryngeal nerve
and the superior laryngeal nerve , branches of the vagus nerve . The
vocal tract is supplied by the hypoglossal nerve and facial nerves .
Electrical stimulation of the periaqueductal gray (PEG) region of the
mammalian midbrain elicit vocalizations. The ability to learn new
vocalizations is only exemplified in humans, seals, cetaceans, and
possibly bats; in humans, this is the result of a direct connection
between the motor cortex , which controls movement, and the motor
neurons in the spinal cord.
Fur Porcupines use their spines for defense.
The fur of mammals has many uses protection, sensory purposes,
waterproofing, and camouflage, with the primary usage being
thermoregulation. The types of hair include definitive, which may be
shed after reaching a certain length; vibrissae, which are sensory
hairs and are most commonly whiskers; pelage , which consists of guard
hairs, under-fur, and awn hair ; spines , which are a type of stiff
guard hair used for defense in, for example, porcupines ; bristles,
which are long hairs usually used in visual signals, such as the mane
of a lion; velli, often called "down fur," which insulates newborn
mammals; and wool which is long, soft and often curly. :99
is negligible in thermoregulation, as some tropical mammals, such as
sloths, have the same length of fur length as some arctic mammals but
with less insulation; and, conversely, other tropical mammals with
short hair have the same insulating value as arctic mammals. The
denseness of fur can increase an animal's insulation value, and arctic
mammals especially have dense fur; for example, the musk ox has guard
hairs measuring 12 inches (30 cm) as well as a dense underfur, which
forms an airtight coat, allowing them to survive in temperatures of
−40 °F (−40 °C). :162–163 Some desert mammals, such as camels,
use dense fur to prevent solar heat from reaching their skin, allowing
the animal to stay cool; a camel's fur may reach 158 °F (70 °C) in
the summer, but the skin stays at 104 °F (40 °C). :188 Aquatic
mammals , conversely, trap air in their fur to conserve heat by
keeping the skin dry. :162–163 A leopard 's disruptively
colored coat provides camouflage for this ambush predator .
Mammalian coats are colored for a variety of reasons, the major
selective pressures including camouflage , sexual selection ,
communication and physiological processes such as temperature
Camouflage is a powerful influence in a large number of
mammals, as it helps to conceal individuals from predators or prey.
Aposematism , warning off possible predators, is the most likely
explanation of the black-and-white pelage of many mammals which are
able to defend themselves, such as in the foul-smelling skunk and the
powerful and aggressive honey badger . In arctic and subarctic
mammals such as the arctic fox (Alopex lagopus), collared lemming
(Dicrostonyx groenlandicus), stoat (Mustela erminea), and snowshoe
hare (Lepus americanus), seasonal color change between brown in summer
and white in winter is driven largely by camouflage. Differences in
female and male coat color may indicate nutrition and hormone levels,
important in mate selection. Some arboreal mammals, notably primates
and marsupials, have shades of violet, green, or blue skin on parts of
their bodies, indicating some distinct advantage in their largely
arboreal habitat due to convergent evolution . The green coloration
of sloths, however, is the result of a symbiotic relationship with
algae . Coat color is sometimes sexually dimorphic , as in many
primate species . Coat color may influence the ability to retain
heat, depending on how much light is reflected. Mammals with a darker
colored coat can absorb more heat from solar radiation, and stay
warmer, and some smaller mammals, such as voles , have darker fur in
the winter. The white, pigmentless fur of arctic mammals, such as the
polar bear, may reflect more solar radiation directly onto the skin.
Goat kids stay with their
mother until they are weaned. Due to the presence of epipubic
bones, non-placental mammals cannot expand their abdomen, being thus
forced to give birth to (or lay eggs that hatch into) fetus-like
Echidna "puggle" (a) compared to various "joeys": Virginia
Gray short-tailed opossum
Gray short-tailed opossum (c),
Eastern quoll (d), Koala
Brushtail possum (f) and
Southern brown bandicoot
Southern brown bandicoot (g).
In male placentals, the penis is used both for urination and
copulation. Depending on the species, an erection by be fueled by
blood flow into vascular, spongy tissue or by muscular action. A penis
may be contained in a sheath when not erect, and some placentals also
have a penis bone (baculum ). Marsupials typically have forked penises
while the monotreme penis generally has four heads with only two
functioning. The testes of most mammals descend into the scrotum which
is typically posterior to the penis but is often anterior in
marsupials. Female mammals generally have a clitoris , labia majora
and labia minora on the outside, while the internal system contains
paired oviducts , 1-2 uteri , 1-2 cervices and a vagina . Marsupials
have two lateral vaginas and a medial vagina. The "vagina" of
monotremes is better understood as a "urogenital sinus". The uterine
systems of placental mammals can vary between a duplex, were there are
two uteri and cervices which open into the vagina, a bipartite, were
two uterine horns have a single cervix that connects to the vagina, a
bicornuate, which consists where two uterine horns that are connected
distally but separate medially creating a Y-shape, and a simplex,
which has a single uterus. :247, 220–21
Most mammals are viviparous , giving birth to live young. However,
the five species of monotreme, the platypus and the four species of
echidna, lay eggs. The monotremes have a sex determination system
different from that of most other mammals. In particular, the sex
chromosomes of a platypus are more like those of a chicken than those
of a therian mammal.
Viviparous mammals are in the subclass Theria; those living today are
in the marsupial and placental infraclasses. Marsupials have a short
gestation period, typically shorter than its estrous cycle and gives
birth to an undeveloped newborn that then undergoes further
development; in many species, this takes place within a pouch-like
sac, the marsupium , located in the front of the mother's abdomen .
This is the plesiomorphic condition among viviparous mammals; the
presence of epipubic bones in all non-placental mammals prevents the
expansion of the torso needed for full pregnancy. Even non-placental
eutherians probably reproduced this way. The placentals give birth to
relatively complete and developed young, usually after long gestation
periods. They get their name from the placenta , which connects the
developing fetus to the uterine wall to allow nutrient uptake.
The mammary glands of mammals are specialized to produce milk, the
primary source of nutrition for newborns. The monotremes branched
early from other mammals and do not have the nipples seen in most
mammals, but they do have mammary glands. The young lick the milk from
a mammary patch on the mother's belly.
Nearly all mammals are endothermic ("warm-blooded"). Most mammals
also have hair to help keep them warm. Like birds, mammals can forage
or hunt in weather and climates too cold for ectothermic
("cold-blooded") reptiles and insects.
Endothermy requires plenty of
food energy, so mammals eat more food per unit of body weight than
most reptiles. Small insectivorous mammals eat prodigious amounts for
their size. A rare exception, the naked mole-rat produces little
metabolic heat, so it is considered an operational poikilotherm .
Birds are also endothermic, so endothermy is not unique to mammals.
Life expectancy and
Maximum life span
Among mammals, species maximum lifespan varies significantly (for
example the shrew has a lifespan of two years, whereas the oldest
bowhead whale is recorded to be 211 years). Although the underlying
basis for these lifespan differences is still uncertain, numerous
studies indicate that the ability to repair
DNA damages is an
important determinant of mammalian lifespan. In a 1974 study by Hart
and Setlow, it was found that
DNA excision repair capability
increased systematically with species lifespan among seven mammalian
Species lifespan was observed to be robustly correlated with
the capacity to recognize
DNA double-strand breaks as well as the
level of the
DNA repair protein
Ku80 . In a study of the cells from
sixteen mammalian species, genes employed in
DNA repair were found to
be up-regulated in the longer-lived species. The cellular level of
DNA repair enzyme poly ADP ribose polymerase was found to
correlate with species lifespan in a study of 13 mammalian species.
Three additional studies of a variety of mammalian species also
reported a correlation between species lifespan and
Running gait . Photographs
Eadweard Muybridge , 1887
Most vertebrates—the amphibians, the reptiles and some mammals such
as humans and bears—are plantigrade , walking on the whole of the
underside of the foot. Many mammals, such as cats and dogs, are
digitigrade , walking on their toes, the greater stride length
allowing more speed.
Digitigrade mammals are also often adept at quiet
movement. Some animals such as horses are unguligrade , walking on
the tips of their toes. This even further increases their stride
length and thus their speed. A few mammals, namely the great apes,
are also known to walk on their knuckles , at least for their front
legs. Giant anteaters and platypuses are also knuckle-walkers. Some
mammals are bipeds , using only two limbs for locomotion, which can be
seen in, for example, humans and the great apes. Bipedal species have
a larger field of vision than quadrupeds, conserve more energy and
have the ability to manipulate objects with their hands, which aids in
foraging. Instead of walking, some bipeds hop, such as kangaroos and
kangaroo rats .
Animals will use different gaits for different speeds, terrain and
situations. For example, horses show four natural gaits, the slowest
horse gait is the walk , then there are three faster gaits which, from
slowest to fastest, are the trot , the canter and the gallop . Animals
may also have unusual gaits that are used occasionally, such as for
moving sideways or backwards. For example, the main human gaits are
bipedal walking and running , but they employ many other gaits
occasionally, including a four-legged crawl in tight spaces. Mammals
show a vast range of gaits , the order that they place and lift their
appendages in locomotion. Gaits can be grouped into categories
according to their patterns of support sequence. For quadrupeds, there
are three main categories: walking gaits, running gaits and leaping
Walking is the most common gait, where some feet are on the
ground at any given time, and found in almost all legged animals.
Running is considered to occur when at some points in the stride all
feet are off the ground in a moment of suspension.
Arboreal locomotion Gibbons are very good
brachiators because their elongated limbs enable them to easily swing
and grasp on to branches.
Arboreal animals frequently have elongated limbs that help them cross
gaps, reach fruit or other resources, test the firmness of support
ahead and, in some cases, to brachiate (swing between trees). Many
arboreal species, such as tree porcupines, silky anteaters , spider
monkeys and possums , use prehensile tails to grasp branches. In the
spider monkey, the tip of the tail has either a bare patch or adhesive
pad, which provides increased friction. Claws can be used to interact
with rough substrates and re-orient the direction of forces the animal
applies. This is what allows squirrels to climb tree trunks that are
so large to be essentially flat from the perspective of such a small
animal. However, claws can interfere with an animal's ability to grasp
very small branches, as they may wrap too far around and prick the
animal's own paw. Frictional gripping is used by primates, relying
upon hairless fingertips. Squeezing the branch between the fingertips
generates frictional force that holds the animal's hand to the branch.
However, this type of grip depends upon the angle of the frictional
force, thus upon the diameter of the branch, with larger branches
resulting in reduced gripping ability. To control descent, especially
down large diameter branches, some arboreal animals such as squirrels
have evolved highly mobile ankle joints that permit rotating the foot
into a 'reversed' posture. This allows the claws to hook into the
rough surface of the bark, opposing the force of gravity. Small size
provides many advantages to arboreal species: such as increasing the
relative size of branches to the animal, lower center of mass,
increased stability, lower mass (allowing movement on smaller
branches) and the ability to move through more cluttered habitat.
Size relating to weight affects gliding animals such as the sugar
glider . Some species of primate, bat and all species of sloth
achieve passive stability by hanging beneath the branch. Both pitching
and tipping become irrelevant, as the only method of failure would be
losing their grip.
Aerial locomotion Play media Slow-motion and
normal speed of Egyptian fruit bats flying
Bats are the only mammals that can truly fly. They fly through the
air at a constant speed by moving their wings up and down (usually
with some fore-aft movement as well). Because the animal is in motion,
there is some airflow relative to its body which, combined with the
velocity of the wings, generates a faster airflow moving over the
wing. This generates a lift force vector pointing forwards and
upwards, and a drag force vector pointing rearwards and upwards. The
upwards components of these counteract gravity, keeping the body in
the air, while the forward component provides thrust to counteract
both the drag from the wing and from the body as a whole.
The wings of bats are much thinner and consist of more bones than
that of birds, allowing bats to maneuver more accurately and fly with
more lift and less drag. By folding the wings inwards towards their
body on the upstroke, they use 35% less energy during flight than
birds. The membranes are delicate, ripping easily; however, the
tissue of the bat's membrane is able to regrow, such that small tears
can heal quickly. The surface of their wings is equipped with
touch-sensitive receptors on small bumps called Merkel cells , also
found on human fingertips. These sensitive areas are different in
bats, as each bump has a tiny hair in the center, making it even more
sensitive and allowing the bat to detect and collect information about
the air flowing over its wings, and to fly more efficiently by
changing the shape of its wings in response.
Semi-fossorial wombat (left) vs. fully fossorial golden
mole (right) See also:
Fossorial creatures live in subterranean environments. Many fossorial
mammals were classified under the, now obsolete, order
such as shrews, hedgehogs and moles.
Fossorial mammals have a fusiform
body, thickest at the shoulders and tapering off at the tail and nose.
Unable to see in the dark burrows, most have degenerated eyes, but
degeneration varies between species; pocket gophers , for example, are
only semi-fossorial and have very small yet functional eyes, in the
fully fossorial marsupial mole the eyes are degenerated and useless,
talpa moles have vestigial eyes and the cape golden mole has a layer
of skin covering the eyes. External ears flaps are also very small or
absent. Truly fossorial mammals have short, stout legs as strength is
more important than speed to a burrowing mammal, but semi-fossorial
mammals have cursorial legs. The front paws are broad and have strong
claws to help in loosening dirt while excavating burrows, and the back
paws have webbing, as well as claws, which aids in throwing loosened
dirt backwards. Most have large incisors to prevent dirt from flying
into their mouth.
Aquatic locomotion ,
Marine mammal , and Aquatic
mammal Play media A pod of short-beaked common dolphins
Fully aquatic mammals, the cetaceans and sirenians , have lost their
legs and have a tail fin to propel themselves through the water.
Flipper movement is continuous. Whales swim by moving their tail fin
and lower body up and down, propelling themselves through vertical
movement, while their flippers are mainly used for steering. Their
skeletal anatomy allows them to be fast swimmers. Most species have a
dorsal fin to prevent themselves from turning upside-down in the
water. The flukes of sirenians are raised up and down in long
strokes to move the animal forward, and can be twisted to turn. The
forelimbs are paddle-like flippers which aid in turning and slowing.
Semi-aquatic mammals, like pinnipeds, have two pairs of flippers on
the front and back, the fore-flippers and hind-flippers. The elbows
and ankles are enclosed within the body. Pinnipeds have several
adaptions for reducing drag . In addition to their streamlined bodies,
they have smooth networks of muscle bundles in their skin that may
increase laminar flow and make it easier for them to slip through
water. They also lack arrector pili , so their fur can be streamlined
as they swim. They rely on their fore-flippers for locomotion in a
wing-like manner similar to penguins and sea turtles . Fore-flipper
movement is not continuous, and the animal glides between each stroke.
Compared to terrestrial carnivorans, the fore-limbs are reduced in
length, which gives the locomotor muscles at the shoulder and elbow
joints greater mechanical advantage; the hind-flippers serve as
stabilizers. Other semi-aquatic mammals include beavers,
hippopotamuses , otters and platypuses. Hippos are very large
semi-aquatic mammals, and their barrel-shaped bodies have graviportal
skeletal structures, adapted to carrying their enormous weight, and
their specific gravity allows them to sink and move along the bottom
of a river.
COMMUNICATION AND VOCALIZATION
Vervet monkeys use at least four distinct alarm calls for
different predators . Further information:
Animal communication and
Many mammals communicate by vocalizing. Vocal communication serves
many purposes, including in mating rituals, as warning calls , to
indicate food sources, and for social purposes. Males often call
during mating rituals to ward off other males and to attract females,
as in the roaring of lions and red deer . The songs of the humpback
whale may be signals to females; they have different dialects in
different regions of the ocean. Social vocalizations include the
territorial calls of gibbons , and the use of frequency in greater
spear-nosed bats to distinguish between groups. The vervet monkey
gives a distinct alarm call for each of at least four different
predators, and the reactions of other monkeys vary according to the
call. For example, if an alarm call signals a python, the monkeys
climb into the trees, whereas the eagle alarm causes monkeys to seek a
hiding place on the ground.
Prairie dogs similarly have complex calls
that signal the type, size, and speed of an approaching predator.
Elephants communicate socially with a variety of sounds including
snorting, screaming, trumpeting, roaring and rumbling. Some of the
rumbling calls are infrasonic , below the hearing range of humans, and
can be heard by other elephants up to 6 miles (9.7 km) away at still
times near sunrise and sunset.
Mammals signal by a variety of means. Many give visual anti-predator
signals , as when deer and gazelle stot , honestly indicating their
fit condition and their ability to escape, or when white-tailed deer
and other prey mammals flag with conspicuous tail markings when
alarmed, informing the predator that it has been detected. Many
mammals make use of scent-marking , sometimes possibly to help defend
territory, but probably with a range of functions both within and
between species. Microbats and toothed whales including oceanic
dolphins vocalize both socially and in echolocation .
The insectivorous giant anteater eats some 30,000 insects per
To maintain a high constant body temperature is energy expensive –
mammals therefore need a nutritious and plentiful diet. While the
earliest mammals were probably predators, different species have since
adapted to meet their dietary requirements in a variety of ways. Some
eat other animals – this is a carnivorous diet (and includes
insectivorous diets). Other mammals, called herbivores , eat plants,
which contain complex carbohydrates such as cellulose. An herbivorous
diet includes subtypes such as granivory (seed eating), folivory (leaf
eating), frugivory (fruit eating), nectarivory (nectar eating),
gummivory (gum eating) and mycophagy (fungus eating). The digestive
tract of an herbivore is host to bacteria that ferment these complex
substances, and make them available for digestion, which are either
housed in the multichambered stomach or in a large cecum. Some
mammals are coprophagous , consuming feces to absorb the nutrients not
digested when the food was first ingested. :131–137 An omnivore eats
both prey and plants. Carnivorous mammals have a simple digestive
tract because the proteins , lipids and minerals found in meat require
little in the way of specialized digestion. Exceptions to this include
baleen whales who also house gut flora in a multi-chambered stomach,
like terrestrial herbivores.
The size of an animal is also a factor in determining diet type
(Allen\'s rule ). Since small mammals have a high ratio of heat-losing
surface area to heat-generating volume, they tend to have high energy
requirements and a high metabolic rate . Mammals that weigh less than
about 18 ounces (510 g) are mostly insectivorous because they cannot
tolerate the slow, complex digestive process of an herbivore. Larger
animals, on the other hand, generate more heat and less of this heat
is lost. They can therefore tolerate either a slower collection
process (those that prey on larger vertebrates) or a slower digestive
process (herbivores). Furthermore, mammals that weigh more than 18
ounces (510 g) usually cannot collect enough insects during their
waking hours to sustain themselves. The only large insectivorous
mammals are those that feed on huge colonies of insects (ants or
termites ). The hypocarnivorous
American black bear
American black bear (Ursus
americanus) vs. the hypercarnivorous polar bear (Ursus maritimus)
Some mammals are omnivores and display varying degrees of carnivory
and herbivory, generally leaning in favor of one more than the other.
Since plants and meat are digested differently, there is a preference
for one over the other, as in bears where some species may be mostly
carnivorous and others mostly herbivorous. They are grouped into
three categories: mesocarnivory (50-70% meat), hypercarnivory (70% and
greater of meat), and hypocarnivory (50% or less of meat). The
dentition of hypocarnivores consists of dull, triangular carnassial
teeth meant for grinding food. Hypercarnivores, however, have conical
teeth and sharp carnassials meant for slashing, and in some cases
strong jaws for bone-crushing, as in the case of hyenas , allowing
them to consume bones; some extinct groups, notably the
Machairodontinae , had saber-shaped canines .
Some physiological carnivores consume plant matter and some
physiological herbivores consuming meat. From a behavioral aspect,
this would make them omnivores, but from the physiological standpoint,
this may be due to zoopharmacognosy . Physiologically, animals must be
able to obtain both energy and nutrients from plant and animal
materials to be considered omnivorous. Thus, such animals are still
able to be classified as carnivores and herbivores when they are just
obtaining nutrients from materials originating from sources that do
not seemingly complement their classification. For example, it is
well documented that some ungulates. such as giraffes, camels, and
cattle, will gnaw on bones to consume particular minerals and
nutrients. Also, cats, which are generally regarded as obligate
carnivores, occasionally eat grass to regurgitate indigestible
material (such as hairballs ), aid with hemoglobin production, and as
Many mammals, in the absence of sufficient food requirements in an
environment, suppress their metabolism and conserve energy in a
process known as hibernation . In the period preceding hibernation,
larger mammals, such as bears, become polyphagic to increase fat
stores, whereas smaller mammals prefer to collect and stash food. The
slowing of the metabolism is accompanied by a decreased heart and
respiratory rate, as well as a drop in internal temperatures, which
can be around ambient temperature in some cases. For example, the
internal temperatures of hibernating arctic ground squirrels can drop
to −2.9 °C (26.8 °F), however the head and neck always stay above
0 °C (32 °F). A few mammals in hot environments aestivate in times
of drought or extreme heat, namely the fat-tailed dwarf lemur
In intelligent mammals, such as primates, the cerebrum is larger
relative to the rest of the brain.
Intelligence itself is not easy to
define, but indications of intelligence include the ability to learn,
matched with behavioral flexibility. Rats , for example, are
considered to be highly intelligent, as they can learn and perform new
tasks, an ability that may be important when they first colonize a
fresh habitat . In some mammals, food gathering appears to be related
to intelligence: a deer feeding on plants has a brain smaller than a
cat, which must think to outwit its prey. A bonobo fishing for
termites with a stick
Tool use by animals
Tool use by animals may indicate different levels of learning and
cognition . The sea otter uses rocks as essential and regular parts of
its foraging behaviour (smashing abalone from rocks or breaking open
shells), with some populations spending 21% of their time making
tools. Other tool use, such as chimpanzees using twigs to "fish" for
termites, may be developed by watching others use tools and may even
be a true example of animal teaching. Tools may even be used in
solving puzzles in which the animal appears to experience a "Eureka
moment" . Other mammals that do not use tools, such as dogs, can also
experience a Eureka moment.
Brain size was previously considered a major indicator of the
intelligence of an animal. Since most of the brain is used for
maintaining bodily functions, greater ratios of brain to body mass may
increase the amount of brain mass available for more complex cognitive
Allometric analysis indicates that mammalian brain size scales
at approximately the ⅔ or ¾ exponent of the body mass. Comparison
of a particular animal's brain size with the expected brain size based
on such allometric analysis provides an encephalisation quotient that
can be used as another indication of animal intelligence. Sperm
whales have the largest brain mass of any animal on earth, averaging
8,000 cubic centimetres (490 in3) and 7.8 kilograms (17 lb) in mature
Self-awareness appears to be a sign of abstract thinking.
Self-awareness, although not well-defined, is believed to be a
precursor to more advanced processes such as metacognitive reasoning .
The traditional method for measuring this is the mirror test , which
determines if an animal possesses the ability of self-recognition.
Mammals that have 'passed' the mirror test include Asian elephants
(some pass, some do not); chimpanzees; bonobos; orangutans;
humans, from 18 months (mirror stage ); bottlenose dolphins killer
whales; and false killer whales.
Social animal Female elephants live in stable
groups, along with their offspring.
Eusociality is the highest level of social organization. These
societies have an overlap of adult generations, the division of
reproductive labor and cooperative caring of young. Usually insects,
such as bees , ants and termites, have eusocial behavior, but it is
demonstrated in two rodent species: the naked mole-rat and the
Damaraland mole-rat .
Presociality is when animals exhibit more than just sexual
interactions with members of the same species, but fall short of
qualifying as eusocial. That is, presocial animals can display
communal living, cooperative care of young, or primitive division of
reproductive labor, but they do not display all of the three essential
traits of eusocial animals. Humans and some species of Callitrichidae
(marmosets and tamarins ) are unique among primates in their degree of
cooperative care of young.
Harry Harlow set up an experiment with
rhesus monkeys , presocial primates, in 1958; the results from this
study showed that social encounters are necessary in order for the
young monkeys to develop both mentally and sexually.
A fission-fusion society is a society that changes frequently in its
size and composition, making up a permanent social group called the
"parent group". Permanent social networks consist of all individual
members of a community and often varies to track changes in their
environment. In a fission–fusion society, the main parent group can
fracture (fission) into smaller stable subgroups or individuals to
adapt to environmental or social circumstances. For example, a number
of males may break off from the main group in order to hunt or forage
for food during the day, but at night they may return to join (fusion)
the primary group to share food and partake in other activities. Many
mammals exhibit this, such as primates (for example orangutans and
spider monkeys ), elephants, spotted hyenas , lions, and dolphins.
Solitary animals defend a territory and avoid social interactions
with the members of its species, except during breeding season. This
is to avoid resource competition, as two individuals of the same
species would occupy the same niche, and to prevent depletion of food.
A solitary animal, while foraging, can also be less conspicuous to
predators or prey. Red kangaroos "boxing" for dominance
In a hierarchy , individuals are either dominant or submissive. A
despotic hierarchy is where one individual is dominant while the
others are submissive, as in wolves and lemurs, and a pecking order
is a linear ranking of individuals where there is a top individual and
a bottom individual. Pecking orders may also be ranked by sex, where
the lowest individual of a sex has a higher ranking than the top
individual of the other sex, as in hyenas. Dominant individuals, or
alphas, have a high chance of reproductive success, especially in
harems where one or a few males (resident males) have exclusive
breeding rights to females in a group. Non-resident males can also be
accepted in harems, but some species, such as the common vampire bat
(Desmodus rotundus), may be more strict.
Some mammals are perfectly monogamous , meaning that they mate for
life and take no other partners (even after the original mate’s
death), as with wolves, Eurasian beavers , and otters. There are
three types of polygamy: either one or multiple dominant males have
breeding rights (polygyny ), multiple males that females mate with
(polyandry), or multiple males have exclusive relations with multiple
females (polygynandry). It is much more common for polygynous mating
to happen, which, excluding leks , are estimated to occur in up to 90%
Lek mating occurs in harems, wherein one or a few males
protect their harem of females from other males who would otherwise
mate with the females, as in elephant seals; or males congregate
around females and try to attract them with various courtship displays
and vocalizations, as in harbor seals.
All higher mammals (excluding monotremes) share two major adaptations
for care of the young: live birth and lactation. These imply a
group-wide choice of a degree of parental care . They may build nests
and dig burrows to raise their young in, or feed and guard them often
for a prolonged period of time. Many mammals are K-selectors , and
invest more time and energy into their young than do r-selectors .
When two animals mate, they both share an interest in the success of
the offspring, though often to different extremes. Mammalian females,
both r- and K-selectors, exhibit some degree of maternal aggression,
another example of parental care, which may be targeted against other
females of the species or the young of other females; however, some
mammals may "aunt" the infants of other females, and care for them.
Mammalian males may play a role in child rearing, as with tenrecs,
however this varies species to species, even within the same genus.
For example, the males of the southern pig-tailed macaque (Macaca
nemestrina) do not participate in child care, whereas the males of the
Japanese macaque (M. fuscata) do.
HUMANS AND OTHER MAMMALS
Mammals in culture
IN HUMAN CULTURE
Upper Paleolithic cave painting of a variety of large mammals,
Lascaux , c. 17,300 years old
Non-human mammals play a wide variety of roles in human culture. They
are the most popular of pets , with tens of millions of dogs, cats and
other animals including rabbits and mice kept by families around the
world. Mammals such as mammoths , horses and deer are among the
earliest subjects of art, being found in
Upper Paleolithic cave
paintings such as at
Lascaux . Major artists such as Albrecht Dürer
George Stubbs and
Edwin Landseer are known for their portraits of
mammals. Many species of mammals have been hunted for sport and for
food; deer and wild boar are especially popular as game animals .
Mammals such as horses and dogs are widely raced for sport, often
combined with betting on the outcome . There is a tension between
the role of animals as companions to humans, and their existence as
individuals with rights of their own . Mammals further play a wide
variety of roles in literature, film, mythology, and religion.
USES AND IMPORTANCE
Cattle have been kept for milk for thousands of years. See
Laboratory animal , and
Domestic mammals form a large part of the livestock raised for meat
across the world. They include (2011) around 1.4 billion cattle , 1.2
billion sheep , 1 billion domestic pigs , and (1985) over 700
million rabbits. Working domestic animals including cattle and horses
have been used for work and transport from the origins of agriculture,
their numbers declining with the arrival of mechanised transport and
agricultural machinery . In 2004 they still provided some 80% of the
power for the mainly small farms in the third world, and some 20% of
the world's transport, again mainly in rural areas. In mountainous
regions unsuitable for wheeled vehicles, pack animals continue to
Mammal skins provide leather for shoes , clothing
and upholstery .
Wool from mammals including sheep, goats and alpacas
has been used for centuries for clothing. Mammals serve a major role
in science as experimental animals , both in fundamental biological
research, such as in genetics, and in the development of new
medicines, which must be tested exhaustively to demonstrate their
safety . Millions of mammals, especially mice and rats, are used in
experiments each year. A knockout mouse is a genetically modified
mouse with an inactivated gene , replaced or disrupted with an
artificial piece of DNA. They enable the study of sequenced genes
whose functions are unknown. A small percentage of the mammals are
non-human primates, used in research for their similarity to humans.
Charles Darwin ,
Jared Diamond and others have noted the importance
of domesticated mammals in the Neolithic development of agriculture
and of civilization , causing farmers to replace hunter-gatherers
around the world. This transition from hunting and gathering to
herding flocks and growing crops was a major step in human history.
The new agricultural economies, based on domesticated mammals, caused
"radical restructuring of human societies, worldwide alterations in
biodiversity, and significant changes in the Earth's landforms and its
atmosphere... momentous outcomes".
Hybrid (biology) A true quagga , 1870
(left) vs. a bred-back quagga , 2014 (right)
Hybrids are offspring resulting from the breeding of two genetically
distinct individuals, which usually will result in a high degree of
heterozygosity, though hybrid and heterozygous are not synonymous. The
deliberate or accidental hybridizing of two or more species of closely
related animals through captive breeding is a human activity which has
been in existence for millennia and has grown for economic purposes.
Hybrids between different subspecies within a species (such as between
Bengal tiger and
Siberian tiger ) are known as intra-specific
hybrids. Hybrids between different species within the same genus (such
as between lions and tigers) are known as interspecific hybrids or
crosses. Hybrids between different genera (such as between sheep and
goats) are known as intergeneric hybrids. Natural hybrids will occur
in hybrid zones , where two populations of species within the same
genera or species living in the same or adjacent areas will interbreed
with each other. Some hybrids have been recognized as species, such as
the red wolf (though this is controversial).
Artificial selection , the deliberate selective breeding of domestic
animals, is being used to breed back recently extinct animals in an
attempt to achieve an animal breed with a phenotype that resembles
that extinct wildtype ancestor. A breeding-back (intraspecific) hybrid
may be very similar to the extinct wildtype in appearance, ecological
niche and to some extent genetics, but the initial gene pool of that
wild type is lost forever with its extinction . As a result, bred-back
breeds are at best vague look-alikes of extinct wildtypes, as Heck
cattle are of the aurochs .
Purebred wild species evolved to a specific ecology can be threatened
with extinction through the process of genetic pollution , the
uncontrolled hybridization, introgression genetic swamping which leads
to homogenization or out-competition from the heterosic hybrid
species. When new populations are imported or selectively bred by
people, or when habitat modification brings previously isolated
species into contact, extinction in some species, especially rare
varieties, is possible.
Interbreeding can swamp the rarer gene pool
and create hybrids, depleting the purebred gene pool. For example, the
endangered wild water buffalo is most threatened with extinction by
genetic pollution from the domestic water buffalo . Such extinctions
are not always apparent from a morphological standpoint. Some degree
of gene flow is a normal evolutionary process, nevertheless,
hybridization threatens the existence of rare species.
Holocene extinction Chart showing the biodiversity of
large mammal species per continent before and after humans arrived
The loss of species from ecological communities, defaunation , is
primarily driven by human activity. This has resulted in empty
forests , ecological communities depleted of large vertebrates. In
Quaternary extinction event , the mass die-off of megafaunal
variety coincided with the appearance of humans, suggesting a human
influence. One hypothesis is that humans hunted large mammals, such as
the woolly mammoth , into extinction.
Various species are predicted to become extinct in the near future ,
among them the rhinoceros , primates , pangolins , and giraffes .
Hunting alone threatens hundreds of mammalian species around the
world. Scientists claim that the growing demand for meat is
contributing to biodiversity loss as this is a significant driver of
deforestation and habitat destruction ; species-rich habitats, such as
significant portions of the
Amazon rainforest , are being converted to
agricultural land for meat production. According to the World
Wildlife Fund 's 2016
Living Planet Index
Living Planet Index , global wildlife
populations have declined 58% since 1970, primarily due to habitat
destruction, over-hunting and pollution. They project that if current
trends continue, 67% of wildlife could disappear by 2020. Another
influence is over-hunting and poaching , which can reduce the overall
population of game animals, especially those located near villages,
as in the case of peccaries . The effects of poaching can especially
be seen in the ivory trade with African elephants. Marine mammals are
at risk from entanglement from fishing gear, notably cetaceans , with
discard mortalities ranging from 65,000 to 86,000 individuals
Several courses of actions are being taken globally, notably the
Convention on Biological Diversity
Convention on Biological Diversity , otherwise known as the Rio
Accord, which includes 189 signatory countries that are focused on
identifying endangered species and habitats. Another notable
conservation organization is the IUCN, which has a membership of over
1,200 governmental and non-governmental organizations.
Recent extinctions can be directly attributable to human influences.
The IUCN characterizes 'recent' extinction as those that have
occurred past the cut-off point of 1500, and around 80 mammal species
have gone extinct since that time and 2015. Some species, such as the
Père David\'s deer are extinct in the wild , and survive solely in
captive populations. Other species, such as the
Florida panther , are
ecologically extinct , surviving in such low numbers that they
essentially have no impact on the ecosystem. :318 Other populations
are only locally extinct (extirpated), still existing elsewhere, but
reduced in distribution, :75–77 as with the extinction of gray
whales in the Atlantic .
* ^ Decreased latency to approach the mirror, repetitious head
circling and close viewing of the marked areas were considered signs
of self-recognition since they do not have arms and cannot touch the
* ^ Diamond discussed this matter further in his 1997 book Guns,
Germs, and Steel .
List of recently extinct mammals – during recorded history
List of prehistoric mammals
List of monotremes and marsupials
List of monotremes and marsupials
List of placental mammals
List of placental mammals
List of mammal genera – living mammals
List of mammalogists
Lists of mammals by population size
Lists of mammals by region
List of threatened mammals of the United States
Mammals described in the 2000s
Mammals in culture
* Prehistoric mammals
* ^ Vaughan, Terry A.; Ryan, James M.; Czaplewski, Nicholas J.
(2013). "Classification of Mammals". Mammalogy (6 ed.). Jones and
Bartlett Learning. ISBN 978-1-284-03209-3 .
* ^ A B Szalay, Frederick S. (1999). "Classification of Mammals
Species Level: Review". Journal of
19 (1): 191–195.
JSTOR 4523980 . doi :10.1080/02724634.1999.10011133
* ^ A B Wilson, D.E.; Reeder, D.M., eds. (2005). "Preface and
Species of the World: A Taxonomic and
Geographic Reference (3rd ed.). Johns Hopkins University Press. p.
xxvi. ISBN 978-0-8018-8221-0 .
OCLC 62265494 .
* ^ "Mammals". The
IUCN Red List
IUCN Red List of Threatened Species. IUCN. April
2010. Retrieved 23 August 2016.
* ^ Rowe, T. (1988). "Definition, diagnosis, and origin of
Mammalia" (PDF). Journal of
Vertebrate Paleontology. 8 (3): 241–264.
doi :10.1080/02724634.1988.10011708 .
* ^ Lyell, Charles (1871). The Student\'s Elements of Geology.
London: John Murray. p. 347. ISBN 978-1-345-18248-4 .
* ^ Cifelli, Richard L.; Davis, Brian M. (2003). "Marsupial
origins". Science. 302 (5652): 1899–1900. PMID 14671280 . doi
* ^ Kemp, T. S. (2005). The Origin and Evolution of Mammals (PDF).
United Kingdom: Oxford University Press. p. 3. ISBN 0-19-850760-7 .
OCLC 232311794 .
* ^ Datta, P. M. (2005). "Earliest mammal with transversely
expanded upper molar from the Late
Triassic (Carnian) Tiki Formation,
South Rewa Gondwana Basin, India". Journal of
25 (1): 200–207. doi :10.1671/0272-4634(2005)0252.0.CO;2 .
* ^ Luo, Zhe-Xi; Martin, Thomas (2007). "Analysis of Molar
Structure and Phylogeny of Docodont Genera" (PDF). Bulletin of
Carnegie Museum of Natural History. 39: 27–47. doi
:10.2992/0145-9058(2007)392.0.CO;2 . Retrieved April 8, 2013.
* ^ McKenna, Malcolm C.; Bell, Susan Groag (1997). Classification
of Mammals above the
Species Level. New York: Columbia University
Press. ISBN 0-231-11013-8 .
OCLC 37345734 .
* ^ Nilsson, M. A.; Churakov, G.; Sommer, M.; van Tran, N.; Zemann,
A.; Brosius, J.; Schmitz, J. (2010). "Tracking
Using Archaic Genomic Retroposon Insertions". PLoS Biology. 8 (7):
e1000436. PMC 2910653 . PMID 20668664 . doi
* ^ Kriegs, Jan Ole; Churakov, Gennady; Kiefmann, Martin; Jordan,
Ursula; Brosius, Jürgen; Schmitz, Jürgen (2006). "Retroposed
Elements as Archives for the Evolutionary History of Placental
Mammals". PLoS Biology. 4 (4): e91. PMC 1395351 . PMID 16515367 .
doi :10.1371/journal.pbio.0040091 .
* ^ A B Nishihara, H.; Maruyama, S.; Okada, N. (2009). "Retroposon
analysis and recent geological data suggest near-simultaneous
divergence of the three superorders of mammals" . Proceedings of the
National Academy of Sciences. 106 (13): 5235–5240. PMC 2655268 .
PMID 19286970 . doi :10.1073/pnas.0809297106 .
* ^ Springer, Mark S.; Murphy, William J.; Eizirik, Eduardo;
O'Brien, Stephen J. (2003). "
Placental mammal diversification and the
Cretaceous–Tertiary boundary" . Proceedings of the National Academy
of Sciences . 100 (3): 1056–1061. PMC 298725 . PMID 12552136 .
doi :10.1073/pnas.0334222100 .
* ^ Tarver, James E.; dos Reis, Mario; Mirarab, Siavash; Moran,
Raymond J.; Parker, Sean; O’Reilly, Joseph E.; King, Benjamin L.;
O’Connell, Mary J.; Asher, Robert J.; Warnow, Tandy; Peterson, Kevin
J.; Donoghue, Philip C. J.; Pisani, Davide (2016). "The
Placental Mammals and the Limits of Phylogenetic
Inference". Genome Biology and Evolution. 8 (2): 330–344. doi
* ^ A B C Springer, Mark S.; Meredith, Robert W.; Janecka, Jan E.;
Murphy, William J. (2011). "The Historical Biogeography of Mammalia" .
Philosophical Transactions of the Royal Society B. 366 (1577):
2478–2502. PMC 3138613 . PMID 21807730 . doi
* ^ Jin Meng, Yuanqing Wang & Chuankui Li (2011). "Transitional
mammalian middle ear from a new
Cretaceous Jehol eutriconodont".
Nature. 472 (7342): 181–185.
Bibcode :2011Natur.472..181M. PMID
21490668 . doi :10.1038/nature09921 .
* ^ Ahlberg, P. E. & Milner, A. R. (April 1994). "The Origin and
Early Diversification of Tetrapods". Nature. 368 (6471): 507–514.
Bibcode :1994Natur.368..507A. doi :10.1038/368507a0 .
* ^ "
Amniota – Palaeos". Archived from the original on
* ^ "
Synapsida overview – Palaeos". Archived from the original on
* ^ A B C Kemp, T. S. (2006). "The origin and early radiation of
the therapsid mammal-like reptiles: a palaeobiological hypothesis"
(PDF). Journal of Evolutionary Biology. 19 (4): 1231–47. PMID
16780524 . doi :10.1111/j.1420-9101.2005.01076.x .
* ^ A B Bennett, A. F.; Ruben, J. A. (1986). "The metabolic and
thermoregulatory status of therapsids". In Hotton III, N.; MacLean, P.
D.; Roth, J. J.; Roth, E. C. The ecology and biology of mammal-like
reptiles. Washington D. C.: Smithsonian Institution Press. pp.
207–218. ISBN 978-0-87474-524-5 .
* ^ Kermack, D.M.; Kermack, K.A. (1984). The evolution of mammalian
characters. Washington D.C.: Croom Helm. ISBN 0-7099-1534-9 . OCLC
* ^ Tanner LH, Lucas SG ">(PDF). Earth-Science Reviews. 65 (1–2):
Bibcode :2004ESRv...65..103T. doi
:10.1016/S0012-8252(03)00082-5 . Archived from the original on October
25, 2007. CS1 maint: Unfit url (link )
* ^ Stephen L. Brusatte. "Superiority, Competition, and Opportunism
in the Evolutionary Radiation of Dinosaurs".
* ^ Gauthier, J.A. (1986). "Saurischian monophyly and the origin of
birds". In Padian, K. (ed.). The Origin of Birds and the Evolution of
Flight. Memoirs of the California Academy of Sciences. 8. San
Francisco: California Academy of Sciences. pp. 1–55. CS1 maint: Uses
editors parameter (link )
* ^ Sereno, P.C. (1991). "Basal archosaurs: phylogenetic
relationships and functional implications". Memoirs of the Society of
Vertebrate Paleontology. 2: 1–53.
JSTOR 3889336 . doi
* ^ MacLeod, N; Rawson, P. F.; Forey, P. L.; Banner, F. T.;
Boudagher-Fadel, M. K.; Bown, P. R.; Burnett, J. A.; Chambers, P.;
Culver, S.; Evans, S. E.; Jeffery, C.; Kaminski, M. A.; Lord, A. R.;
Milner, A. C.; Milner, A. R.; Morris, N.; Owen, E.; Rosen, B. R.;
Smith, A. B.; Taylor, P. D.; Urquhart, E.; Young, J. R. (1997). "The
Cretaceous–Tertiary biotic transition". Journal of the Geological
Society. 154 (2): 265–292. doi :10.1144/gsjgs.154.2.0265 .
* ^ Hunt, David M.; Hankins, Mark W.; Collin, Shaun P.; Marshall,
N. J. Evolution of Visual and Non-visual Pigments. London: Springer.
p. 73. ISBN 978-1-4614-4354-4 .
OCLC 892735337 .
* ^ Bakalar, Nicholas (2006). "
Jurassic "Beaver" Found; Rewrites
History of Mammals". National Geographic News. Retrieved 28 May 2016.
* ^ Hall, M. I.; Kamilar, J. M.; Kirk, E. C. (24 October 2012).
"Eye shape and the nocturnal bottleneck of mammals" . Proceedings of
the Royal Society B: Biological Sciences. 279 (1749): 4962–4968. PMC
3497252 . PMID 23097513 . doi :10.1098/rspb.2012.2258 .
* ^ Luo, Zhe-Xi (2007). "Transformation and diversification in
early mammal evolution". Nature. 450 (7172): 1011–19. Bibcode
:2007Natur.450.1011L. PMID 18075580 . doi :10.1038/nature06277 .
* ^ Pickrell, John (2003). "Oldest
Marsupial Fossil Found in
China". National Geographic News. Retrieved 28 May 2016.
* ^ A B Luo, Zhe-Xi; Yuan, Chong-Xi; Meng, Qing-Jin; Ji, Qiang
Jurassic eutherian mammal and divergence of marsupials and
placentals". Nature. 476 (7361): 442–445. Bibcode
:2011Natur.476..442L. PMID 21866158 . doi :10.1038/nature10291 .
* ^ Ji, Qiang; Luo, Zhe-Xi; Yuan, Chong-Xi; Wible, John R.; Zhang,
Jian-Ping; Georgi, Justin A. (2002). "The earliest known eutherian
mammal". Nature. 416: 816–822. PMID 11976675 . doi :10.1038/416816a
* ^ M. J. Novacek; G. W. Rougier; J. R. Wible; M. C. McKenna; D.
Dashzeveg & I. Horovitz (1997). "
Epipubic bones in eutherian mammals
from the Late
Cretaceous of Mongolia". Nature. 389 (6650): 483–486.
Bibcode :1997Natur.389..483N. PMID 9333234 . doi :10.1038/39020 .
* ^ Power, Michael L.; Schulkin, Jay (2012). "Evolution of Live
Birth in Mammals". Evolution of the
Human Placenta. Baltimore: Johns
Hopkins University Press. p. 68. ISBN 978-1-4214-0643-5 .
* ^ Rowe, Timothy; Rich, Thomas H.; Vickers-Rich, Patricia;
Springer, Mark; Woodburne, Michael O. (2007). "The oldest platypus and
its bearing on divergence timing of the platypus and echidna clades" .
Proceedings of the National Academy of Sciences. 105 (4): 1238–1242.
PMC 2234122 . PMID 18216270 . doi :10.1073/pnas.0706385105 .
* ^ Grant, Tom (1995). "Reproduction". The Platypus: A Unique
Mammal. Sydney: University of New South Wales. p. 55. ISBN
OCLC 33842474 .
* ^ Goldman, Armond S. (2012). "Evolution of Immune Functions of
the Mammary Gland and Protection of the Infant". Breastfeeding
Medicine. 7 (3): 132–142. doi :10.1089/bfm.2012.0025 .
* ^ A B Rose, Kenneth D. (2006). The Beginning of the Age of
Mammals. Baltimore: Johns Hopkins University Press. pp. 82–83. ISBN
OCLC 646769601 .
* ^ Brink, A.S. (1955). "A study on the skeleton of Diademodon".
Palaeontologia Africana. 3: 3–39.
* ^ Kemp, T.S. (1982). Mammal-like reptiles and the origin of
mammals. London: Academic Press. p. 363. ISBN 978-0-12-404120-2 . OCLC
* ^ Estes, R. (1961). "Cranial anatomy of the cynodont reptile
Thrinaxodon liorhinus". Bulletin of the Museum of Comparative Zoology
* ^ "Thrinaxodon: The Emerging Mammal". National Geographic Daily
News. February 11, 2009. Retrieved August 26, 2012.
* ^ A B Bajdek, Piotr; Qvarnström, Martin; Owocki, Krzysztof;
Sulej, Tomasz; Sennikov, Andrey G.; Golubev, Valeriy K.;
Niedźwiedzki, Grzegorz (2015). "Microbiota and food residues
including possible evidence of pre-mammalian hair in Upper Permian
coprolites from Russia". Lethaia. doi :10.1111/let.12156 .
* ^ Botha-Brink, Jennifer; Angielczyk, Kenneth D. (2010). "Do
extraordinarily high growth rates in Permo-
(Therapsida, Anomodontia) explain their success before and after the
Permian extinction?". Zoological Journal of the Linnean Society.
160 (2): 341–365. doi :10.1111/j.1096-3642.2009.00601.x .
* ^ Paul, G.S. (1988). Predatory Dinosaurs of the World. New York:
Simon and Schuster. p. 464. ISBN 978-0-671-61946-6 .
OCLC 18350868 .
* ^ J.M. Watson & J.A.M. Graves (1988). "
Monotreme Cell-Cycles and
the Evolution of Homeothermy". Australian Journal of Zoology. CSIRO.
36 (5): 573–584. doi :10.1071/ZO9880573 .
* ^ McNab, Brian K. (1980). "Energetics and the limits to the
temperate distribution in armadillos". Journal of Mammalogy (American
Society of Mammalogists). 61 (4): 606–627.
JSTOR 1380307 . doi
* ^ Kielan−Jaworowska, Z.; Hurum, J.H.. (2006). "Limb posture in
early mammals: Sprawling or parasagittal" (PDF). Acta Palaeontologica
Polonica. 51 (3): 10237–10239.
* ^ Lillegraven, Jason A.; Kielan-Jaworowska, Zofia; Clemens,
William A. (1979).
Mesozoic Mammals: The First Two-Thirds of Mammalian
History. University of California Press. p. 321. ISBN
OCLC 5910695 .
* ^ Oftedal, O.T. (2002). "The mammary gland and its origin during
synapsid evolution". Journal of Mammary Gland Biology and Neoplasia. 7
(3): 225–252. PMID 12751889 . doi :10.1023/A:1022896515287 .
* ^ Oftedal, O.T. (2002). "The origin of lactation as a water
source for parchment-shelled eggs". Journal of Mammary Gland Biology
and Neoplasia. 7 (3): 253–266. PMID 12751890 . doi
* ^ A B Sahney, S., Benton, M.J. and Ferry, P.A. (2010). "Links
between global taxonomic diversity, ecological diversity and the
expansion of vertebrates on land" (PDF). Biology Letters. 6 (4):
544–547. PMC 2936204 . PMID 20106856 . doi
:10.1098/rsbl.2009.1024 . CS1 maint: Multiple names: authors list
* ^ Smith, F. A.; Boyer, A. G.; Brown, J. H.; Costa, D. P.; Dayan,
T.; Ernest, S. K. M.; Evans, A. R.; Fortelius, M.; Gittleman, J. L.;
Hamilton, M. J.; Harding, L. E.; Lintulaakso, K.; Lyons, S. K.;
McCain, C.; Okie, J. G.; Saarinen, J. J.; Sibly, R. M.; Stephens, P.
R.; Theodor, J.; Uhen, M. D. (2010). "The Evolution of Maximum Body
Size of Terrestrial Mammals". Science. 330 (6008): 1216–1219.
Bibcode :2010Sci...330.1216S. doi :10.1126/science.1194830 .
* ^ Simmons, Nancy B.; Seymour, Kevin L.; Habersetzer, Jörg;
Gunnell, Gregg F. (2007). "Primitive Early
Eocene bat from Wyoming and
the evolution of flight and echolocation". Nature. 451: 818–821.
PMID 18270539 . doi :10.1038/nature06549 .
* ^ Bininda-Emonds, O.R.P.; Cardillo, M.; Jones, K.E.; Beck, Robin
M. D.; Grenyer, Richard; Price, Samantha A.; Vos, Rutger A.; et al.
(2007). "The delayed rise of present-day mammals" (PDF). Nature. 446
Bibcode :2007Natur.446..507B. PMID 17392779 . doi
:10.1038/nature05634 . CS1 maint: Explicit use of et al. (link )
* ^ A B Wible, J. R.; Rogier, G. W.; Novacek, M. J.; Asher, R. J.
Cretaceous eutherians and Laurasian origin for placental
mammals near the K/T boundary". Nature. 447 (7147): 1003–06. Bibcode
:2007Natur.447.1003W. PMID 17581585 . doi :10.1038/nature05854 .
* ^ O'Leary, Maureen A.; Bloch, Jonathan I.; Flynn, John J.;
Gaudin, Timothy J.; Giallombardo, Andres; Giannini, Norberto P.;
Goldberg, Suzann L.; Kraatz, Brian P.; Luo, Zhe-Xi; Meng, Jin;
Novacek, Michael J.; Perini, Fernando A.; Randall, Zachary S.;
Rougier, Guillermo; Sargis, Eric J.; Silcox, Mary T.; Simmons, Nancy
b.; Spaulding, Micelle; Velazco, Paul M.; Weksler, Marcelo; Wible,
John r.; Cirranello, Andrea L.; Cirranello, Andrea L. (8 February
Mammal Ancestor and the Post–K-Pg Radiation of
Placentals". Science . 339 (6120): 662–667. Bibcode
:2013Sci...339..662O. PMID 23393258 . doi :10.1126/science.1229237 .
Retrieved 9 February 2013.
* ^ Halliday, Thomas J. D.; Upchurch, Paul; Goswami, Anjali (2015).
"Resolving the relationships of
Paleocene placental mammals".
Biological Reviews. doi :10.1111/brv.12242 .
* ^ Halliday, Thomas John Dixon; Upchurch, Paul; Goswami, Anjali
(2016). "Eutherians experienced elevated evolutionary rates in the
immediate aftermath of the Cretaceous–Palaeogene mass extinction"
(PDF). Proceedings of the Royal Society B. 283 (1833): 20153026. PMC
4936024 . PMID 27358361 . doi :10.1098/rspb.2015.3026 .
* ^ A B C Ni, Xijun; Gebo, Daniel L.; Dagosto, Marian; Meng, Jin;
Tafforeau, Paul; Flynn, John J.; Beard, K. Christopher (6 June 2013).
"The oldest known primate skeleton and early haplorhine evolution".
Nature. 498 (7452): 60–64.
Bibcode :2013Natur.498...60N. PMID
23739424 . doi :10.1038/nature12200 .
* ^ Romer, Sherwood A.; Parsons, Thomas S. (1977). The Vertebrate
Body. Philadelphia: Holt-Saunders International. pp. 129–145. ISBN
OCLC 60007175 .
* ^ Purves, William K.; Sadava, David E.; Orians, Gordon H.; Helle,
H. C. (2001). Life: The Science of Biology (6 ed.). New York: Sinauer
Associates, Inc. p. 593. ISBN 978-0-7167-3873-2 .
OCLC 874883911 .
* ^ Anthwal, Neal; Joshi, Leena; Tucker, Abigail S. (2012).
"Evolution of the mammalian middle ear and jaw: adaptations and novel
structures" . Journal of Anatomy. 222 (1): 147–160. PMC 3552421 .
PMID 22686855 . doi :10.1111/j.1469-7580.2012.01526.x .
* ^ van Nievelt, Alexander F. H.; Smith, Kathleen K. (2005). "To
replace or not to replace: the significance of reduced functional
tooth replacement in marsupial and placental mammals". Paleobiology.
31 (2): 324–346. doi :10.1666/0094-8373(2005)0312.0.co;2 .
* ^ Mao, Fangyuan; Wang, Yuanqing; Meng, Jin (2015). "A Systematic
Study on Tooth Enamel Microstructures of Lambdopsalis bulla
(Multituberculate, Mammalia) - Implications for Multituberculate
Biology and Phylogeny" . PLOS ONE. 10 (5): e0128243. PMC 4447277 .
PMID 26020958 . doi :10.1371/journal.pone.0128243 .
* ^ Osborn, Henry F. (1900). "Origin of the Mammalia, III.
Occipital Condyles of Reptilian Tripartite Type". The American
Naturalist. 34 (408): 943–947.
JSTOR 2453526 . doi :10.1086/277821 .
* ^ Crompton, A. W.; Jenkins, Jr., F. A. (1973). "Mammals from
Reptiles: A Review of Mammalian Origins". Annual Review of Earth and
Planetary Sciences. 1: 131–155. doi
* ^ A B Power, Michael L.; Schulkin, Jay (2013). The Evolution Of
Human Placenta. Baltimore: Johns Hopkins University Press. pp.
1890–1891. ISBN 978-1-4214-0643-5 .
OCLC 940749490 .
* ^ Dierauf, Leslie A.; Gulland, Frances M. D. (2001). CRC Handbook
Mammal Medicine: Health, Disease, and Rehabilitation (2
ed.). Boca Raton: CRC Press. p. 154. ISBN 978-1-4200-4163-7 . OCLC
* ^ Lui, J. H.; Hansen, D. V.; Kriegstein, A. R. (2011).
"Development and Evolution of the
Human Neocortex" . Cell. 146 (1):
18–36. PMC 3610574 . PMID 21729779 . doi
* ^ Keeler, Clyde E. (1933). "Absence of the
Corpus callosum as a
Mendelizing Character in the House Mouse" . Proceedings of the
National Academy of Sciences of the United States of America. 19 (6):
JSTOR 86284 . PMC 1086100 .
PMID 16587795 . doi :10.1073/pnas.19.6.609 .
* ^ Levitzky, Michael G. (2013). "Mechanics of Breathing".
Pulmonary physiology (8 ed.). New York: McGraw-Hill Medical. ISBN
OCLC 940633137 .
* ^ A B Umesh, Kumar B. (2011). "Pulmonary Anatomy and Physiology".
Handbook of Mechanical Ventilation (1 ed.). New Delhi: Jaypee Brothers
Medical Publishing. p. 12. ISBN 978-93-80704-74-6 .
OCLC 945076700 .
* ^ Standring, Susan; Borley, Neil R. (2008). Gray's anatomy: the
anatomical basis of clinical practice (40 ed.). London: Churchill
Livingstone. pp. 960–962. ISBN 978-0-8089-2371-8 .
OCLC 213447727 .
* ^ Betts, J. Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody
E.; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James A.; Womble,
Mark; Young, Kelly A. (2013). Anatomy & physiology. Houston: Rice
University Press. pp. 787–846. ISBN 978-1-938168-13-0 . OCLC
* ^ A B C D E F G H I Feldhamer, George A.; Drickamer, Lee C.;
Vessey, Stephen H.; Merritt, Joseph H.; Krajewski, Carey (2007).
Mammalogy: Adaptation, Diversity, Ecology (3 ed.). Baltimore: Johns
Hopkins University Press. ISBN 978-0-8018-8695-9 .
OCLC 124031907 .
* ^ Tinker, Spencer W. (1988). Whales of the World. Brill Archive.
p. 51. ISBN 978-0-935848-47-2 .
* ^ Romer, A. S. (1959). The vertebrate story (4 ed.). Chicago:
University of Chicago Press. ISBN 978-0-226-72490-4 .
* ^ de Muizon, Christian; Lange-Badré, Brigitte (1997).
"Carnivorous dental adaptations in tribosphenic mammals and
phylogenetic reconstruction". Lethaia. 30 (4): 353–366. doi
* ^ Langer, Peter (1984). "Comparative Anatomy of the
Mammalian Herbivores". Quarterly Journal of Experimental Physiology.
69 (3): 615–625. PMID 6473699 . doi
* ^ Vaughan, Terry A.; Ryan, James M.; Czaplewski, Nicholas J.
(2011). "Perissodactyla". Mammalogy (5 ed.). Jones and Bartlett. p.
322. ISBN 978-0-7637-6299-5 .
OCLC 437300511 .
* ^ Flower, William H.; Lydekker, Richard (1946). An Introduction
to the Study of Mammals Living and Extinct. London: Adam and Charles
Black. p. 496. ISBN 978-1-110-76857-8 .
* ^ Sreekumar, S. (2010). Basic Physiology. PHI
Learning Pvt. Ltd.
pp. 180–181. ISBN 978-8120-34107-4 .
* ^ Cheifetz, Adam S. (2010). Oxford American Handbook of
Gastroenterology and Hepatology. Oxford: Oxford University Press, USA.
p. 165. ISBN 0199830126 .
* ^ Kuntz, Erwin (2008). Hepatology: Textbook and Atlas. Germany:
Springer. p. 38. ISBN 978-3-540-76838-8 .
* ^ Ortiz, Rudy M. (2001). "Osmoregulation in Marine Mammals".
Journal of Experimental Biology. 204 (11): 1831–1844. PMID 11441026
* ^ A B C Roman, Alfred Sherwood; Parsons, Thomas S. (1977). The
Vertebrate Body. Philadelphia: Holt-Saunders International. pp.
396–399. ISBN 978-0-03-910284-5 .
* ^ Biological Reviews - Cambridge Journals
* ^ Dawkins, R.; Wong, Y. (2016). The Ancestor\'s Tale: A
Pilgrimage to the Dawn of Evolution (2nd ed.). Boston: Mariner Books.
p. 281. ISBN 978-0-544-85993-7 .
* ^ A B C Fitch, W. T. (2006). "Production of Vocalizations in
Mammals". In Brown, K. Encyclopedia of Language and Linguistics (PDF).
Oxford: Elsevier. pp. 115–121.
* ^ Langevin, Paul; Barclay, Robert M. R. (1990). "Hypsignathus
monstrosus". Mammalian Species. 357: 1–4. doi :10.2307/3504110 .
* ^ Weissengruber, G. E.; Forstenpointner, G.; Peters, G.;
Kübber-Heiss, A.; W. T., Fitch (2002). "Hyoid apparatus and pharynx
in the lion (Panthera leo), jaguar (Panthera onca), tiger (Panthera
tigris), cheetah (Acinonyx jubatus), liger (Panthera leo × Panthera
tigris), Tigon (Panthera tigris x Panthera leo) and the domestic cat.
Felis silvestris f. catus)" . Journal of Anatomy. 201 (3): 195–209.
PMC 1570911 . PMID 12363272 . doi :10.1046/j.1469-7580.2002.00088.x
* ^ Stoeger, Angela S.; Heilmann, Gunnar; Zeppelzauer, Matthias;
Ganswindt, André; Hensman, Sean; Charlton, Benjamin D. (2012).
"Visualizing Sound Emission of
Elephant Vocalizations: Evidence for
Two Rumble Production Types" . PLOS ONE. 7 (11): e48907. PMC 3498347
. PMID 23155427 . doi :10.1371/journal.pone.0048907 .
* ^ Clark, C. W. (2004). "
Baleen whale infrasonic sounds: Natural
variability and function". Journal of the Acoustical Society of
America. 115 (5): 2554. doi :10.1121/1.4783845 .
* ^ A B Dawson, T. J.; Webster, K. N.; Maloney, S. K. (2014). "The
fur of mammals in exposed environments; do crypsis and thermal needs
necessarily conflict? The polar bear and marsupial koala compared".
Journal of Comparative Physiology B. 184 (2): 273–284. doi
* ^ Caro, Tim (2005). "The Adaptive Significance of Coloration in
Mammals" (PDF). BioScience. 55 (2): 125–136. doi
* ^ Caro, Tim (February 2009). "Contrasting coloration in
terrestrial mammals" . Phil Trans Royal Soc B. 364 (1516): 537–548.
PMC 2674080 . PMID 18990666 . doi :10.1098/rstb.2008.0221 .
* ^ Mills, L. Scott; Zimova, Marketa; Oyler, Jared; Running,
Steven; Abatzoglou, John T.; Lukacs, Paul M. (April 2013). "Camouflage
mismatch in seasonal coat color due to decreased snow duration" .
PNAS. 110 (8): 7360–7365. PMC 3645584 . PMID 23589881 . doi
* ^ Bradley et. al, Brenda (2012). "Coat Color Variation and
Gene Expression in Rhesus Macaques (Macaca Mulatta)"
(PDF). Journal of Mammalian Evolution. 20: 263–70. doi
* ^ Prum, Richard O.; Torres, Rodolfo H. (2004). "Structural
colouration of mammalian skin: convergent evolution of coherently
scattering dermal collagen arrays" (PDF). Journal of Experimental
Biology. 207 (12): 2157–72. doi :10.1242/jeb.00989 .
* ^ Suutari, Milla; Majaneva, Markus; Fewer, David P.; Voirin,
Bryson; Aiello, Annette; Friedl, Thomas; Chiarello, Adriano G.;
Blomster, Jaanika (2010). "Molecular evidence for a diverse green
algal community growing in the hair of sloths and a specific
association with Trichophilus welckeri (Chlorophyta, Ulvophyceae)".
Evolutionary Biology. 10 (86). PMC 2858742 . PMID 20353556 . doi
* ^ Plavcan, J. M. (2001). "
Sexual dimorphism in primate
evolution". American Journal of Physical Anthropology. 116 (33):
25–53. PMID 11786990 . doi :10.1002/ajpa.10011 .
* ^ Maxwell, Kenneth E. (2013). The Sex Imperative: An Evolutionary
Tale of Sexual Survival. Springer. pp. 112–13. ISBN 9781489959881 .
* ^ Vaughan, Terry A; et al. (2011). Mammalogy. Jones & Bartlett
Publishers. p. 387. ISBN 9781449644376 . CS1 maint: Explicit use of et
al. (link )
* ^ Wallis M.C., Waters P.D., Delbridge M.L., Kirby P.J., Pask
A.J., Grützner F., Rens W., Ferguson-Smith M.A., Graves J.A.M.;
Waters; Delbridge; Kirby; Pask; Grützner; Rens; Ferguson-Smith;
Graves; et al. (2007). "Sex determination in platypus and echidna:
autosomal location of SOX3 confirms the absence of SRY from
monotremes". Chromosome Research. 15 (8): 949–959. PMID 18185981 .
doi :10.1007/s10577-007-1185-3 . CS1 maint: Multiple names: authors
list (link )
* ^ Marshall Graves, Jennifer A. (2008). "Weird
Animal Genomes and
the Evolution of
Vertebrate Sex and Sex Chromosomes" (PDF). Annual
Review of Genetics. 42: 568–586. PMID 18983263 . doi
* ^ Novacek, Michael J.; Rougier, Guillermo W.; Wible, John R.;
McKenna, Malcolm C.; Dashzeveg, Demberelyin; Horovitz, Inés (1997).
Epipubic bones in eutherian mammals from the Late
Mongolia". Nature. 389: 483–486. PMID 9333234 . doi :10.1038/39020 .
* ^ Morgan, Sally (2005). "
Mammal Behavior and Lifestyle". Mammals.
Chicago: Raintree. p. 6. ISBN 978-1-4109-1050-9 .
OCLC 53476660 .
* ^ Verma, P. S.; Pandey, B. P. (2013). ISC Biology Book I for
Class XI. New Delhi: S. Chand and Company. p. 288. ISBN
* ^ Oftedal, O. T. (2002). "The mammary gland and its origin during
synapsid evolution". Journal of Mammary Gland Biology and Neoplasia. 7
(3): 225–252. PMID 12751889 . doi :10.1023/a:1022896515287 .
* ^ Campbell, Neil A.; Reece, Jane B. (2002). Biology (6 ed.).
Benjamin Cummings. p. 845. ISBN 978-080536-624-2 .
OCLC 47521441 .
* ^ Buffenstein, Rochelle; Yahav, Shlomo (1991). "Is the naked
mole-rat Hererocephalus glaber an endothermic yet poikilothermic
mammal?". Journal of Thermal Biology. 16 (4): 227–232. doi
* ^ Schmidt-Nielsen, Knut; Duke, James B. (1997). "Temperature
Animal Physiology: Adaptation and Environment (5 ed.).
Cambridge. p. 218. ISBN 978-0-521-57098-5 .
OCLC 35744403 .
* ^ A B Lorenzini, A.; Johnson, F. B.; Oliver, A.; Tresini, M.;
Smith, J. S.; Hdeib, M.; Sell, C.; Cristofalo, V. J.; Stamato, T. D.
(2009). "Significant correlation of species longevity with
strand break recognition but not with telomere length" . Mech. Ageing
Dev. 130 (11-12): 784–792. PMC 2799038 . PMID 19896964 . doi
* ^ Hart, R. W.; Setlow, R. B. (1974). "Correlation between
deoxyribonucleic acid excision-repair and life-span in a number of
mammalian species" . Proceedings of the National Academy of Sciences
of the U.S.A. 71 (6): 2169–2173. PMC 388412 . PMID 4526202 .
* ^ Ma S, Upneja A, Galecki A, Tsai YM, Burant CF, Raskind S, Zhang
Q, Zhang ZD, Seluanov A, Gorbunova V, Clish CB, Miller RA, Gladyshev
VN (2016). "Cell culture-based profiling across mammals reveals DNA
repair and metabolism as determinants of species longevity" . Elife.
5. PMC 5148604 . PMID 27874830 . doi :10.7554/eLife.19130 .
* ^ Grube K, Bürkle A (1992). "Poly(ADP-ribose) polymerase
activity in mononuclear leukocytes of 13 mammalian species correlates
with species-specific life span" . Proceedings National Academy
Sciences of the U.S.A. 89 (24): 11759–11763. PMC 50636 . PMID
* ^ Francis, A. A.; Lee, W. H.; Regan, J. D. (1981). "The
DNA excision repair of ultraviolet-induced lesions to
the maximum life span of mammals". Mechanisms of Ageing of
Development. 16 (2): 181–189. PMID 7266079 .
* ^ Treton, J. A.; Courtois, Y. (1982). "Correlation between DNA
excision repair and mammalian lifespan in lens epithelial cells". Cell
Biol. Int. Rep. 6 (3): 253–60. PMID 7060140 .
* ^ Maslansky, C. J.; Williams, G. M. (1985). "Ultraviolet
DNA repair synthesis in hepatocytes from species of
differing longevities". Mechanisms of Ageing of Development. 29 (2):
191–203. PMID 3974310 .
* ^ "Leg and foot". Archived from the original on 2008-04-04.
Retrieved 3 August 2008.
* ^ Walker, Warren F.; Homberger, Dominique G. (1998). Anatomy and
Dissection of the Fetal
Pig (5 ed.). New York: W. H. Freeman and
Company. p. 3. ISBN 978-0-7167-2637-1 .
OCLC 40576267 .
* ^ Orr, CM. (2005). "
Knuckle-walking anteater: a convergence test
of adaptation for purported knuckle-walking features of African
Hominidae". Am. J. Phys. Anthropol. 128 (3): 639–58. PMID 15861420 .
doi :10.1002/ajpa.20192 .
* ^ Fish, FE; Frappell, PB; Baudinette, RV; MacFarlane, PM (2001).
"Energetics of terrestrial locomotion of the platypus Ornithorhynchus
anatinus" (PDF). The Journal of Experimental Biology. 204 (Pt 4):
797–803. PMID 11171362 .
* ^ Dhingra, P. (2004). "Comparative
Bipedalism – How the Rest of
Animal Kingdom Walks on two legs". Anthropological Science. 131
* ^ Alexander, R. M. (2004). "Bipedal animals, and their
differences from humans" . Journal of Anatomy. 204 (5): 321–330. PMC
1571302 . PMID 15198697 . doi :10.1111/j.0021-8782.2004.00289.x .
* ^ A B Dagg, Anne I. (1973). "Gaits in Mammals".
Mammal Review. 3
(4): 135–154. doi :10.1111/j.1365-2907.1973.tb00179.x .
* ^ Roberts, Tristan D. M. (1995). Understanding Balance: The
Mechanics of Posture and Locomotion. San Diego: Nelson Thornes. p.
211. ISBN 978-1-56593-416-0 .
OCLC 33167785 .
* ^ A B C Cartmill, M. (1985). "Climbing". In Hildebrand, M.;
Bramble, D. M.; Liem, K. F.; Wake, D. B. Functional Vertebrate
Morphology. Cambridge: Belknap Press. pp. 73–88. ISBN
OCLC 11114191 .
* ^ Vernes, Karl (2001). "Gliding Performance of the Northern
Squirrel (Glaucomys sabrinus) in Mature Mixed Forest of Eastern
Canada" (PDF). Journal of Mammalogy. 82 (4): 1026–1033. doi
* ^ A. Barba, Lorena (October 2011). "
Bats – the only flying
mammals". Bio-Aerial Locomotion. Retrieved 20 May 2016.
* ^ "
Bats In Flight Reveal Unexpected Aerodynamics". ScienceDaily.
2007. Retrieved July 12, 2016.
* ^ Hedenström, Anders; Johansson, L. C. (2015). "
aerodynamics, kinematics and flight morphology" (PDF). Journal of
Experimental Biology. 218: 653–663. PMID 25740899 . doi
* ^ "
Bats save energy by drawing in wings on upstroke".
ScienceDaily. 2012. Retrieved July 12, 2016.
* ^ Taschek, Karen (2008). Hanging with Bats: Ecobats, Vampires,
and Movie Stars. Albuquerque, New Mexico: University of New Mexico
Press. p. 14. ISBN 978-0-8263-4403-8 .
OCLC 191258477 .
* ^ Sterbing-D'Angeloa, Susanne; Chadhab, Mohit; Chiuc, Chen;
Falkc, Ben; Xianc, Wei; Barceloc, Janna; Zookd, John M.; Mossa,
Cynthia F. (2011). "
Bat wing sensors support flight control" (PDF).
Proceedings of the National Academy of Sciences of the United States
of America. 108 (27): 11291–11296. PMC 3131348 . PMID 21690408 .
doi :10.1073/pnas.1018740108 .
* ^ Shimer, H. W. (1903). "Adaptations to Aquatic, Arboreal,
Cursorial Habits in Mammals. III. Fossorial
Adaptations". The American Naturalist. 37 (444): 819–825. JSTOR
2455381 . doi :10.1086/278368 .
* ^ Perry, D. A. (1949). "The anatomical basis of swimming in
Whales". Journal of Zoology. 119 (1): 49–60. doi
* ^ Fish, F. E.; Hui, C. A. (1991). "Dolphin swimming — a review"
Mammal Review. 21 (4): 181–195. doi
* ^ Marsh, Helene (1989). "Chapter 57: Dugongidae". Fauna of
Australia (PDF). 1. Canberra: Australian Government Publications. ISBN
OCLC 27492815 . Archived from the original on
2013-05-11. CS1 maint: BOT: original-url status unknown (link )
* ^ A B Berta, pp. 62–64.
* ^ A B Fish, F. E. (2003). "Maneuverability by the sea lion
Zalophus californianus: Turning performance of an unstable body
design". Journal of Experimental Biology. 206 (4): 667–74. PMID
12517984 . doi :10.1242/jeb.00144 .
* ^ A B Riedman, M. (1990). The Pinnipeds: Seals, Sea Lions, and
Walruses. University of California Press. ISBN 978-0-520-06497-3 .
OCLC 19511610 .
* ^ Fish, F. E. (1996). "Transitions from drag-based to lift-based
propulsion in mammalian swimming". Integrative and Comparative
Biology. 36 (6): 628–41. doi :10.1093/icb/36.6.628 .
* ^ Fish, Frank E. (2000). "Biomechanics and Energetics in Aquatic
and Semiaquatic Mammals:
Platypus to Whale" (PDF). Physiological and
Biochemical Zoology. 73 (6): 683–698. PMID 11121343 . doi
:10.1086/318108 . Archived from the original (PDF) on 2016-08-04.
* ^ Eltringham, S. K. (1999). "Anatomy and Physiology". The Hippos.
London: T & AD Poyser Ltd. p. 8. ISBN 978-0-8566-1131-5 . OCLC
* ^ "
Hippopotamus amphibius". National Geographic.
Archived from the original on 2014-11-25. Retrieved 30 April 2016.
* ^ A B Seyfarth, R. M.; Cheney, D. L.; Marler, Peter (1980).
Monkey Alarm Calls: Semantic communication in a Free-Ranging
Animal Behaviour. 28 (4): 1070–1094. doi
* ^ Zuberbühler, Klause (2001). "Predator-specific alarm calls in
Campbell's monkeys, Cercopithecus campbelli". Behavioral Ecology and
Sociobiology. 50 (5): 414–442.
JSTOR 4601985 . doi
* ^ Slabbekoorn, Hans; Smith, Thomas B. (2002). "
Bird song, ecology
and speciation". Philosophical Transactions: Biology Sciences. 357
(1420): 493–503. doi :10.1098/rstb.2001.1056 .
* ^ Bannister, John L. (2008). "Baleen Whales (Mysticetes)". In F.
Perrin, William; Würsig, Bernd; Thewissen, J. G. M. Encyclopedia of
Marine Mammals (2 ed.). Academic Press. pp. 80–89. ISBN
* ^ Norris, Scott (2002). "Creatures of Culture? Making the Case
for Cultural Systems in Whales and Dolphins" (PDF). BioScience. 52
(1): 9–14. doi :10.1641/0006-3568(2002)0522.0.CO;2 .
* ^ Boughman, Janette W. (1998). "Vocal learning by greater
spear-nosed bats". Proceedings: Biological Sciences. 265 (1392):
227–233. doi :10.1098/rspb.1998.0286 .
* ^ "Prairie dogs\' language decoded by scientists". CBC News. 21
June 2013. Retrieved 20 May 2015.
* ^ Mayell, Hillary (3 March 2004). "Elephants Call Long-Distance
After-Hours". National Geographic. Retrieved 15 November 2016.
* ^ Maynard Smith, John ; Harper, David (2003).
Oxford Series in Ecology and Evolution. Oxford University Press. pp.
61–63. ISBN 978-0-19-852684-1 .
OCLC 54460090 .
* ^ FitzGibbon, C. D.; Fanshawe, J. H. (1988). "
Thomson’s gazelles: an honest signal of condition" (PDF). Behavioral
Ecology and Sociobiology. 23 (2): 69–74. doi :10.1007/bf00299889 .
Archived from the original (PDF) on 2014-02-25.
* ^ Bildstein, Keith L. (May 1983). "Why White-Tailed
Their Tails". The American Naturalist. 121 (5): 709–715. JSTOR
2460873 . doi :10.1086/284096 .
* ^ Johnson, Roger P. (August 1973). "Scent Marking in Mammals".
Animal Behaviour. 21 (3): 521–535. doi
* ^ Schevill, W.E.; McBride, A.F. (1956). "Evidence for
echolocation by cetaceans". Deep-Sea Research. 3 (2): 153–154.
Bibcode :1956DSR.....3..153S. doi :10.1016/0146-6313(56)90096-x .
* ^ Wilson, W.; Moss, C. (2004). Thomas, J., ed. "Echolocation in
Bats and Dolphins". Chicago University Press: 22. ISBN
OCLC 50143737 .
* ^ Au, Whitlow W. L. (1993). The Sonar of Dolphins.
Springer-Verlag. ISBN 978-3-540-97835-0 .
OCLC 26158593 .
* ^ Naugher, K. B. (2004). "Anteaters (Myrmecophagidae)". In
Hutchins, M.; Kleiman, D. G.; Geist, V.; McDade, M. С. Grzimek's
Animal Life Encyclopedia. 13 (2 ed.). Gale. pp. 171–179. ISBN
OCLC 471032508 .
* ^ Langer, Peter (1984). "Comparative Anatomy of the
Mammalian Herbivores". Quarterly Journal of Experimental Physiology.
69: 615–625. PMID 6473699 . doi :10.1113/expphysiol.1984.sp002848 .
* ^ Sanders, Jon G.; Beichman, Annabel C.; Roman, Joe; Scott,
Jarrod J.; Emerson, David; McCarthy, James J.; Girguis, Peter R.
(2015). "Baleen whales host a unique gut microbiome with similarities
to both carnivores and herbivores". Nature Communications. 6: 8285.
PMC 4595633 . PMID 26393325 . doi :10.1038/ncomms9285 .
* ^ Speaksman, J. R. (1996). "Energetics and the evolution of body
size in small terrestrial mammals" (PDF). Symposia of the Zoological
Society of London (69): 69–81.
* ^ A B Don E. Wilson; David Burnie, eds. (2001). Animal: The
Definitive Visual Guide to the World's Wildlife (1st ed.). DK
Publishing. pp. 86–89. ISBN 978-0-7894-7764-4 .
OCLC 46422124 .
* ^ A B van Valkenburgh, Blaire (2007). "Déjà vu: the evolution
of feeding morphologies in the Carnivora". Integrative and Comparative
Biology. 47 (1): 147–163. PMID 21672827 . doi :10.1093/icb/icm016 .
* ^ Sacco, Tyson; van Valkenburgh, Blaire (2004). "Ecomorphological
indicators of feeding behaviour in the bears (Carnivora: Ursidae)".
Journal of Zoology. 263 (1): 41–54. doi :10.1017/S0952836904004856 .
* ^ Singer, M. S.; Bernays, E. A. (2003). "Understanding omnivory
needs a behavioral perspective". Ecology. 84 (10): 2532–2537. doi
* ^ Hutson, Jarod M.; Burke, Chrissina C.; Haynes, Gary
(2013-12-01). "Osteophagia and bone modifications by giraffe and other
large ungulates". Journal of Archaeological Science. 40 (12):
4139–4149. doi :10.1016/j.jas.2013.06.004 .
* ^ "Why Do Cats Eat Grass?".
Pet MD. Retrieved 13 January 2017.
* ^ Geiser, Fritz (2004). "Metabolic Rate and Body Temperature
Hibernation and Daily Torpor". Annu. Rev. Physiol.
66: 239–274. PMID 14977403 . doi
* ^ Humphries, M. M.; Thomas, D.W.; Kramer, D.L. (2003). "The role
of energy availability in mammalian hibernation: A cost-benefit
approach". Physiological and Biochemical Zoology. 76 (2): 165–179.
PMID 12794670 . doi :10.1086/367950 .
* ^ Barnes, Brian M. (1989). "Freeze Avoidance in a Mammal: Body
Temperatures Below 0 °C in an Arctic Hibernator". Science. 244
(4912): 1593–1595. PMID 2740905 . doi :10.1126/science.2740905 .
* ^ Geiser, Fritz (2010). "Aestivation in Mammals and Birds". In
Navas, Carlos Arturo; Carvalho, José Eduardo. Aestivation: Molecular
and Physiological Aspects. Springer-Verlag. pp. 95–113. ISBN
978-3-642-02420-7 . doi :10.1007/978-3-642-02421-4 .
* ^ Mann, Janet; Patterson, Eric M. (2013). "Tool Use by Aquatic
Animals" (PDF). Philosophical Transactions of the Royal Society B. 368
(1630): 20120424. doi :10.1098/rstb.2012.0424 .
* ^ Raffaele, Paul (2011). Among the Great Apes: Adventures on the
Trail of Our Closest Relatives. New York: Harper. p. 83. ISBN
OCLC 674694369 .
* ^ Köhler, Wolfgang (1925). The Mentality of Apes. Liveright.
ISBN 978-0-87140-108-3 .
OCLC 2000769 .
* ^ McGowan, R. T.; Rehn, T.; Norling, Y.; Keeling, L. J. (2014).
"Positive affect and learning: exploring the "Eureka Effect" in dogs".
Animal Cognition. 17 (13): 577–587. PMID 24096703 . doi
* ^ Karbowski, Jan (2007). "Global and regional brain metabolic
scaling and its functional consequences". BioMed Central Biology. 5
(18). doi :10.1186/1741-7007-5-18 .
* ^ Marino, Lori (2007). "Cetacean Brains: How Aquatic Are They?".
The Anatomical Record. 290 (6): 694–700. doi :10.1002/ar.20530 .
* ^ Gallup, Jr., G. G. (1970). "Chimpanzees: Self recognition".
Science. 167 (3914): 86–87.
Bibcode :1970Sci...167...86G. PMID
4982211 . doi :10.1126/science.167.3914.86 .
* ^ Plotnik, J.M., de Waal, F.B.M. and Reiss, D. (2006).
"Self-recognition in an Asian elephant" (PDF). PNAS. 103 (45):
Bibcode :2006PNAS..10317053P. doi
:10.1073/pnas.0608062103 . CS1 maint: Multiple names: authors list
* ^ S., Robert (1986). "Ontogeny of mirror behavior in two species
of great apes". American Journal of Primatology. 10 (2): 109–117.
doi :10.1002/ajp.1350100202 .
* ^ Walraven, V., van Elsacker, L. and Verheyen, R. (1995).
"Reactions of a group of pygmy chimpanzees (Pan paniscus) to their
mirror images: evidence of self-recognition". Primates. 36: 145–150.
doi :10.1007/bf02381922 . CS1 maint: Multiple names: authors list
* ^ Leakey, Richard (1994). "The Origin of the Mind". The Origin Of
Humankind. New York: BasicBooks. p. 150. ISBN 978-0-465-05313-1 . OCLC
* ^ Archer, John (1992). Ethology and
Human Development. Rowman &
Littlefield. pp. 215–218. ISBN 978-0-389-20996-6 .
OCLC 25874476 .
* ^ A B Marten, K.; Psarakos, S. (1995). "Evidence of
self-awareness in the bottlenose dolphin (Tursiops truncatus)". In
Parker, S.T.; Mitchell, R.; Boccia, M.
Self-awareness in Animals and
Humans: Developmental Perspectives. Cambridge: Cambridge University
Press. pp. 361–379. ISBN 978-0-521-44108-7 .
OCLC 28180680 .
* ^ A B Delfour, F. & Marten, K. (2001). "Mirror image processing
in three marine mammal species: Killer whales (Orcinus orca), false
killer whales (Pseudorca crassidens) and California sea lions
(Zalophus californianus)". Behavioural Processes. 53 (3): 181–190.
PMID 11334706 . doi :10.1016/s0376-6357(01)00134-6 .
* ^ Jarvis, J. U. M. (1981). "
Eusociality in a mammal: cooperative
breeding in naked mole-rat colonies". Science. 212 (4494): 571–573.
JSTOR 1686202 . doi :10.1126/science.7209555 .
* ^ Jacobs, D.S.; et al. (1991). "The colony structure and
dominance hierarchy of the Damaraland mole-rat, Cryptomys damarensis
(Rodentia: Bathyergidae) from Namibia". Journal of Zoology. 224 (4):
553–576. doi :10.1111/j.1469-7998.1991.tb03785.x .
* ^ Hardy, Sarah B. (2009). Mothers and Others: The Evolutionary
Origins of Mutual Understanding. Boston: Belknap Press of Harvard
University Press. pp. 92–93.
* ^ Harlow, H. F.; Suomi, S. J. (1971). "Social Recovery by
Isolation-Reared Monkeys". Proceedings of the National Academy of
Sciences of the United States of America. 68 (7): 1534–1538. doi
* ^ van Schaik, Carel P. (1999). "The Socioecology of
Fission-Fusion Sociality in Orangutans". Biomedical and Life Sciences.
40 (1): 69–86. doi :10.1007/BF02557703 .
* ^ Archie, Elizabeth A.; Cynthia J. Moss; Susan C. Alberts (March
2005). "The ties that bind: genetic relatedness predicts the fission
and fusion of social groups in wild African elephants". Proceedings of
the Royal Society B. 273: 513–522. PMC 1560064 . PMID 16537121 .
doi :10.1098/rspb.2005.3361 .
* ^ Smith, Jennifer E.; Sandra K. Memenis; Kay E. Holekamp (2007).
"Rank-related partner choice in the fission–fusion society of the
spotted hyena (Crocuta crocuta)" (PDF). Behavioral Ecology and
Sociobiology. 61 (5): 753–765. doi :10.1007/s00265-006-0305-y .
* ^ Matoba, Tomoyuki; Kutsukake, Nobuyuki; Hasegawa, Toshikazu
(2013). Hayward, Matt, ed. "Head Rubbing and Licking Reinforce Social
Bonds in a Group of Captive African Lions, Panthera leo" . PLoS ONE. 8
(9): e73044. PMC 3762833 . PMID 24023806 . doi
* ^ Krützen, Michael; Barré, Lynne M.; Connor, Richard C.; Mann,
Janet; Sherwin, William B. (2004). "‘O father: where art thou?’—
Paternity assessment in an open fission–fusion society of wild
bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia".
Molecular Ecology. 13 (7): 1975–1990. PMID 15189218 . doi
* ^ Martin, Claude (1991). The Rainforests of West Africa: Ecology
— Threats — Conservation (1 ed.). Springer. ISBN 978-3-0348-7726-8
. doi :10.1007/978-3-0348-7726-8 .
* ^ le Roux, Aliza; Michael I. Cherry; Lorenz Gygax (5 May 2009).
"Vigilance behaviour and fitness consequences: comparing a solitary
foraging and an obligate group-foraging mammal". Behavioral Ecology
and Sociobiology. 63: 1097–1107. doi :10.1007/s00265-009-0762-1 .
* ^ Palagi, Elisabetta; Norscia, Ivan (2015). Samonds, Karen E.,
ed. "The Season for Peace: Reconciliation in a Despotic
catta)" . PLoS ONE. 10 (11): e0142150. PMC 4646466 . PMID 26569400
. doi :10.1371/journal.pone.0142150 .
* ^ East, Marion L.; Hofer, Heribert (2000). "Male spotted hyenas
(Crocuta crocuta) queue for status in social groups dominated by
females". Behavioral Ecology. 12 (15): 558–568. doi
* ^ Samuels, A.; Silk, J. B.; Rodman, P. (1984). "Changes in the
dominance rank and reproductive behavior of male bonnet macaques
Animal Behaviour. 32: 994–1003. doi
* ^ Delpietro, H.A.; Russo, R.G. (2002). "Observations of the
common vampire bat (Desmodus rotundus) and the hairy-legged vampire
bat (Diphylla ecaudata) in captivity". Mammalian Biology. 67 (2):
65–78. doi :10.1078/1616-5047-00011 .
* ^ Kleiman, Devra G. (1977). "Monogamy in Mammals". The Quarterly
Review of Biology. 52 (1): 39–69. PMID 857268 . doi :10.1086/409721
* ^ Holland, B.; Rice, W. R. (1998). "Perspective: Chase-Away
Sexual Selection: Antagonistic Seduction vs. Resistance" (PDF).
Evolution. 52: 1–7. doi :10.2307/2410914 .
* ^ Clutton-Brock, T. H. (1989). "Review Lecture: Mammalian Mating
Systems". Proceedings of the Royal Society of London. Series B,
Biological Sciences. 236 (1285): 339–372. PMID 2567517 . doi
* ^ Leboeuf, J. B. (1972). "Sexual behavior in the northern
elephant seal Mirounga angustirostris". Behaviour. 41 (1): 1–26.
JSTOR 4533425 . PMID 5062032 . doi :10.1163/156853972X00167 .
* ^ Boness, D. J.; Bowen, D.; Buhleier, B. M.; Marshall, G. J.
(2006). "Mating tactics and mating system of an aquatic-mating
pinniped: the harbor seal, Phoca vitulina" (PDF). Behavioral Ecology
and Sociobiology. 61: 119–30. doi :10.1007/s00265-006-0242-9 .
* ^ Klopfer, P. H. (1981). "Origins of Parental Care". In
Gubernick, D. J. Parental Care in Mammals. New York: Plenum Press.
ISBN 978-1-4613-3150-6 .
OCLC 913709574 .
* ^ Murthy, Rekha; Bearman, Gonzalo; Brown, Sherrill; Bryant,
Kristina (2015). "Animals in Healthcare Facilities: Recommendations to
Minimize Potential Risks" (PDF). Infection Control and Hospital
Epidemiology. 36 (5): 495–516. doi :10.1017/ice.2015.15 .
* ^ The Humane Society of the United States. "U.S.
Statistics". Retrieved 27 April 2012.
* ^ USDA. "U.S.
Rabbit Industry profile" (PDF). Retrieved 10 July
* ^ McKie, Robin (26 May 2013). "Prehistoric cave art in the
The Guardian . Retrieved 9 November 2016.
* ^ Jones, Jonathan (27 June 2014). "The top 10 animal portraits in
The Guardian . Retrieved 24 June 2016.
* ^ "
Hunting in the United States: An Analysis of Hunter
Demographics and Behavior Addendum to the 2001 National Survey of
Fishing, Hunting, and Wildlife-Associated Recreation Report 2001-6".
Fishery and Wildlife Service (USA). Retrieved 24 June 2016.
* ^ "Recreational Hog
Hunting Popularity Soaring". Gramd View
Outdoors. Retrieved 24 June 2016.
* ^ Nguyen, Jenny; Wheatley, Rick (2015).
Hunting For Food: Guide
to Harvesting, Field Dressing and Cooking Wild Game. F+W Media. pp.
6–77. ISBN 978-1-4403-3856-4 . Chapters on hunting deer, wild hog
(boar), rabbit, and squirrel.
* ^ "
Horse racing". Archived from the original on 21 December 2013.
Retrieved 6 May 2014.
* ^ Genders, Roy (1981). Encyclopaedia of Greyhound Racing. Pelham
Books. ISBN 978-0-7207-1106-6 .
OCLC 9324926 .
* ^ Plous, S. (1993). "The Role of Animals in
Journal of Social Issues. 49 (1): 1–9. doi
* ^ Fowler, Karen Joy (26 March 2014). "Top 10 books about
intelligent animals". The Guardian. Retrieved 9 November 2016.
* ^ Gamble, Nikki; Yates, Sally (2008). Exploring Children's
Literature (2 ed.). Los Angeles: Sage. ISBN 978-1-4129-3013-0 . OCLC
* ^ "Books for Adults". Seal Sitters. Retrieved 9 November 2016.
* ^ Paterson, Jennifer (2013). "Animals in Film and Media". Oxford
Bibliographies. doi :10.1093/obo/9780199791286-0044 .
* ^ Johns, Catherine (2011). Cattle: History, Myth, Art. London:
The British Museum Press. ISBN 978-0-7141-5084-0 .
OCLC 665137673 .
* ^ Robert Hans van Gulik. Hayagrīva: The Mantrayānic Aspect of
Horse-cult in China and Japan. Brill Archive. p. 9.
* ^ Grainger, Richard (24 June 2012). "
Lion Depiction across
Ancient and Modern Religions". ALERT. Archived from the original on 23
September 2016. Retrieved November 6, 2016.
* ^ "Graphic detail Charts, maps and infographics. Counting
The Economist . 27 July 2011. Retrieved November 6, 2016.
Cattle Today. "Breeds of
Cattle at CATTLE TODAY".
Cattle-today.com. Retrieved November 6, 2016.
* ^ Lukefahr, S.D.; Cheeke, P.R. "
Rabbit project development
strategies in subsistence farming systems". Food and Agriculture
Organization . Retrieved November 6, 2016.
* ^ Pond, Wilson G. (2004). Encyclopedia of
Animal Science. New
York: CRC Press. pp. 248–250. ISBN 978-0-8247-5496-9 .
* ^ "History of Leather". Moore & Giles. Retrieved 10 November
* ^ Braaten, Ann W. (2005). "Wool". In Steele, Valerie.
Clothing and Fashion. 3.
Thomson Gale . pp. 441–443.
ISBN 978-0-684-31394-8 .
OCLC 963977000 .
* ^ Quiggle, Charlotte. "Alpaca: An Ancient Luxury." Interweave
Knits Fall 2000: 74-76.
* ^ "Genetics Research".
Animal Health Trust. Retrieved November 6,
* ^ "Drug Development".
Animal Research.info. Retrieved November 6,
* ^ "EU statistics show decline in animal research numbers".
Speaking of Research. 2013. Retrieved November 6, 2016.
* ^ Helen R. Pilcher (2003). "It\'s a knockout". Nature. doi
:10.1038/news030512-17 . Retrieved November 6, 2016.
* ^ Y Zan et al., Production of knockout rats using ENU mutagenesis
and a yeast-based screening assay, Nat. Biotechnol. (2003).Archived
June 11, 2010, at the
Wayback Machine .
* ^ "The supply and use of primates in the EU". European Biomedical
Research Association. 1996. Archived from the original on 2012-01-17.
* ^ Carlsson, H. E.; Schapiro, S. J.; Farah, I.; Hau, J. (2004).
"Use of primates in research: A global overview". American Journal of
Primatology. 63 (4): 225–237. PMID 15300710 . doi :10.1002/ajp.20054
* ^ Weatherall, D., et al., (The Weatherall Committee) (2006). The
use of non-human primates in research (PDF) (Report). London, UK:
Academy of Medical Sciences. Archived from the original (PDF) on
2013-03-23. CS1 maint: Multiple names: authors list (link )
* ^ Diamond, J. M. (1997). "Part 2: The rise and spread of food
production". Guns, Germs, and Steel: the Fates of
Human Societies (1
ed.). New York: W.W. Norton & Company. ISBN 978-0-393-03891-0 . OCLC
* ^ Larson, Greger; Burger, Joachim (April 2013). "A population
genetics view of animal domestication" (PDF). Trends in Genetics. 29
(4): 197–205. doi :10.1016/j.tig.2013.01.003 .
* ^ Zeder, Melinda A. (August 2008). "
Domestication and early
agriculture in the Mediterranean Basin: Origins, diffusion, and
impact". PNAS. 105 (33): 11597–11604. PMC 2575338 . PMID 18697943
. doi :10.1073/pnas.0801317105 .
* ^ Price, E. (2008). Principles and applications of domestic
animal behavior: an introductory text. Sacramento: Cambridge
University Press. ISBN 978-1-84593-398-2 .
OCLC 226038028 .
* ^ Taupitz, Jochen; Weschka, Marion (2009). CHIMBRIDS - Chimeras
and Hybrids in Comparative European and International Research.
Heidelberg: Springer. p. 13. ISBN 978-3-540-93869-9 .
OCLC 495479133 .
* ^ Chambers, Steven M.; Fain, Steven R.; Fazio, Bud; Amaral,
Michael (2012). "An account of the taxonomy of North American wolves
from morphological and genetic analyses". North American Fauna. 77: 2.
doi :10.3996/nafa.77.0001 .
* ^ van Vuure, T. (2005). Retracing the
Aurochs – History,
Morphology and Ecology of an extinct wild Ox. Pensoft Publishers. ISBN
OCLC 940879282 .
* ^ Mooney, H. A.; Cleland, E. E. (2001). "The evolutionary impact
of invasive species" . PNAS . 98 (10): 5446–5451. Bibcode
:2001PNAS...98.5446M. PMC 33232 . PMID 11344292 . doi
* ^ Le Roux, Johannes J.; Foxcroft, Llewellyn C.; Herbst, Marna;
MacFadyen, Sandra (2014). "Genetic analysis shows low levels of
hybridization between African wildcats (
Felis silvestris lybica) and
domestic cats (F. s. catus) in South Africa" . Ecology and Evolution.
5 (2): 288–299. PMC 4314262 . PMID 25691958 . doi
* ^ Wilson, Andrew (2003). "Australia's state of the forests
report". p. 107. Missing or empty url= (help )
* ^ Rhymer, J. M.; Simberloff, D. (November 1996). "
Hybridization and Introgression". Annual Review of Ecology and
Systematics. Annual Reviews. 27: 83–109. doi
* ^ Potts, Brad M. (2001). Barbour, Robert C.; Hingston, Andrew B.,
Genetic pollution from farm forestry using eucalypt species and
hybrids : a report for the RIRDC/L&WA/FWPRDC Joint Venture
Agroforestry Program. Rural Industrial Research and Development
Corporation of Australia. ISBN 978-0-642-58336-9 .
OCLC 48794104 .
* ^ A B Dirzo, Rodolfo; Young, Hillary S.; Galetti, Mauro;
Ceballos, Gerardo; Isaac, Nick J. B.; Collen, Ben (2014). "Defaunation
in the Anthropocene" (PDF). Science . 345 (6195): 401–406. doi
* ^ Primack, Richard (2014). Essentials of Conservation Biology (6
ed.). Sunderland, MA: Sinauer Associates, Inc. Publishers. pp.
217–245. ISBN 978-1-605-35289-3 .
OCLC 876140621 .
* ^ Vignieri, Sacha (2014). "Vanishing fauna". Science . 345
(6195): 392–395. doi :10.1126/science.345.6195.392 .
* ^ Burney, David A.; Flannery, Timothy F. (2005). "Fifty millennia
of catastrophic extinctions after human contact" (PDF). Trends in
Ecology and Evolution. 20 (7): 395–401. PMID 16701402 . doi
:10.1016/j.tree.2005.04.022 . Archived from the original on
2010-06-10. CS1 maint: BOT: original-url status unknown (link )
* ^ Diamond, J. (1984). "Historic extinctions: a Rosetta stone for
understanding prehistoric extinctions". In Martin, P. S.; Klein, R. G.
Quaternary extinctions: A prehistoric revolution. Tucson: University
of Arizona Press. pp. 824–862. ISBN 978-0-8165-1100-6 . OCLC
* ^ 7 Iconic Animals Humans Are Driving to Extinction. Live Science
. November 22, 2013.
* ^ Poachers Drive Javan Rhino to
Extinction in Vietnam by John R.
Platt October 25, 2011
* ^ Estrada, Alejandro; Garber, Paul A.; Rylands, Anthony B.; Roos,
Christian; Fernandez-Duque, Eduardo; Di Fiore, Anthony; Anne-Isola
Nekaris, K.; Nijman, Vincent; Heymann, Eckhard W.; Lambert, Joanna E.;
Rovero, Francesco; Barelli, Claudia; Setchell, Joanna M.; Gillespie,
Thomas R.; Mittermeier, Russell A.; Arregoitia, Luis Verde; de Guinea,
Miguel; Gouveia, Sidney; Dobrovolski, Ricardo; Shanee, Sam; Shanee,
Noga; Boyle, Sarah A.; Fuentes, Agustin; MacKinnon, Katherine C.;
Amato, Katherine R.; Meyer, Andreas L. S.; Wich, Serge; Sussman,
Robert W.; Pan, Ruliang; Kone, Inza; Li, Baoguo (January 18, 2017).
"Impending extinction crisis of the world’s primates: Why primates
Science Advances . 3 (1): e1600946. doi
* ^ Fletcher, Martin (January 31, 2015). "Pangolins: why this cute
prehistoric mammal is facing extinction". The Telegraph. Retrieved 3
* ^ Carrington, Damian (December 8, 2016). "
extinction after devastating decline, experts warn". The Guardian.
Retrieved 3 February 2017.
* ^ Pennisi, Elizabeth (October 18, 2016). "People are hunting
primates, bats, and other mammals to extinction". Science . Retrieved
3 February 2017.
* ^ Ripple, William J.; Abernethy, Katharine; Betts, Matthew G.;
Chapron, Guillaume; Dirzo, Rodolfo; Galetti, Mauro; Levi, Taal;
Lindsey, Peter A.; Macdonald, David W.; Machovina, Brian; Newsome,
Thomas M.; Peres, Carlos A.; Wallach, Arian D.; Wolf, Christopher;
Young, Hillary (2016). "Bushmeat hunting and extinction risk to the
world\'s mammals". Royal Society Open Science. 3: 1–16. doi
* ^ Williams, Mark; Zalasiewicz, Jan; Haff, P. K.; Schwägerl,
Christian; Barnosky, Anthony D.; Ellis, Erle C. (2015). "The
Anthropocene Biosphere". The Anthropocene Review. 2 (3): 196–219.
doi :10.1177/2053019615591020 .
* ^ Morell, Virginia (August 11, 2015). "Meat-eaters may speed
worldwide species extinction, study warns". Science . Retrieved 3
* ^ Machovina, B.; Feeley, K. J.; Ripple, W. J. (2015).
"Biodiversity conservation: The key is reducing meat consumption".
Science of The Total Environment. 536: 419–431. PMID 26231772 . doi
* ^ "World on track to lose two-thirds of wild animals by 2020,
major report warns".
The Guardian . Retrieved 3 February 2017.
* ^ Report 2016: risk and resilience in a new era (Report). Living
World Wildlife Fund
World Wildlife Fund . pp. 1–148. ISBN 978-2-940529-40-7 .
OCLC 961331618 .
* ^ Redford, K. H. (1992). "The empty forest" (PDF). BioScience. 42
JSTOR 1311860 . doi :10.2307/1311860 .
* ^ Peres, Carlos A.; Nascimento, Hilton S. (2006). "Impact of Game
Hunting by the Kayapo´ of South-eastern Amazonia: Implications for
Wildlife Conservation in Tropical Forest Indigenous Reserves". Human
Exploitation and Biodiversity Conservation. Topics in Biodiversity and
Conservation. 3. pp. 287–313. ISBN 978-1-4020-5283-5 . OCLC
* ^ Altrichter, M.; Boaglio, G. (2004). "Distribution and Relative
Abundance of Peccaries in the Argentine Chaco: Associations with Human
Factors". Biological Conservation. 116 (2): 217–225. doi
* ^ "African Elephant".
IUCN Red List
IUCN Red List of Threatened
Retrieved 3 February 2017.
* ^ Alverson, D. L.; Freeburg, M. H.; Murawski, S. A.; Pope, J. G.
(1996) . "Bycatch of Marine Mammals". A global assessment of fisheries
bycatch and discards. Rome: Food and
Agriculture Organization of the
United Nations. ISBN 978-92-5-103555-9 .
OCLC 31424005 .
* ^ Glowka, Lyle; Burhenne-Guilmin, Françoise; Synge, Hugh;
McNeely, Jeffrey A.; Gündling, Lothar (1994). IUCN environmental
policy and law paper. Guide to the Convention on Biodiversity.
International Union for Conservation of Nature. ISBN 978-2-8317-0222-3
OCLC 32201845 .
* ^ "About IUCN". International Union for Conservation of Nature.
Retrieved 3 February 2017.
* ^ Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.;
García, Andrés; Pringle, Robert M.; Palmer, Todd M. (2015).
"Accelerated modern human–induced species losses: Entering the sixth
Science Advances . 1 (5): e1400253. doi
* ^ Fisher, Diana O.; Blomberg, Simon P. (2011). "Correlates of
rediscovery and the detectability of extinction in mammals" .
Proceedings of the Royal Society B: Biological Sciences. 278 (1708):
1090–1097. PMC 3049027 . PMID 20880890 . doi
* ^ Ceballos, G.; Ehrlich, A. H.; Ehrlich, P. R. (2015). The
Annihilation of Nature:
Extinction of Birds and Mammals.
Baltimore: Johns Hopkins University Press. p. 69. ISBN