Pecora
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Pecora is an
infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
of even-toed hoofed
mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
with
ruminant Ruminants (suborder Ruminantia) are ungulate, hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principally ...
digestion. Most members of Pecora have cranial appendages projecting from their
frontal bones The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...
; only two extant genera lack them, ''
Hydropotes The water deer (''Hydropotes inermis'') is a small deer superficially more similar to a musk deer than a true deer. Native to China and Korea, there are two subspecies: the Chinese water deer (''Hydropotes inermis inermis'') and the Korean water ...
'' and ''
Moschus Moschus ( el, Μόσχος), ancient Greek bucolic poet and student of the Alexandrian grammarian Aristarchus of Samothrace, was born at Syracuse and flourished about 150 BC. Aside from his poetry, he was known for his grammatical work, nothing o ...
''. The name “Pecora” comes from the Latin word ''pecus'', which means “horned livestock”.Bubenik, A. Epigenetical, Morphological, Physiological, and Behavioral Aspects of Evolution of Horns, Pronghorns, and Antlers. in ''Horns, Pronghorns, and Antlers''. G. Bubenik and A. Bubenik eds. Springer-Verlag. New York. 1990 Although most pecorans have cranial appendages, only some of these are properly called “horns”, and many scientists agree that these appendages did not arise from a common ancestor, but instead evolved independently on at least two occasions.Janis, C., K. Scott. The Interrelationships of Higher Ruminant Families with Special Emphasis on the Members of the Cervoidea. ''American Museum Novitates''. 2893: 1-85. 1987. http://digitallibrary.amnh.org/dspace/handle/2246/5180 Likewise, while Pecora as a group is supported by both molecular and morphological studies, morphological support for interrelationships between pecoran families is disputed.


Evolutionary history

The first fossil ruminants appeared in the Early Eocene and were small, likely omnivorous, forest-dwellers. Artiodactyls with cranial appendages first occur in the early
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
. The appearance of Pecora during the Miocene suggests that its rapid diversification may correspond to the climate change events of that epoch. It is likely that the antelopes, giraffids, and pronghorns evolved in an open environment while the cervids, including the caribou, evolved in
woodland habitat.
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The type of gallop in Pecorian species is shown to be closely related to their environment and anatomy, where light Pecorian species use both flexed and extended suspensions in their fast gallops. The white-tail and mule-deer have been observed to primarily use the extended suspension, since in this phase of their gallop they leap over bushes and logs that are present in their brush environment. However, heavy Pecorian species do not use extended suspensions as most have backs that slope downward with shorter hind legs.


Taxonomy and Classification

Pecora is an
infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
within the larger suborder
Ruminantia Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
, and is the
sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a family, familial relationship, it is sometimes used endearingly to r ...
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
to the
infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
Tragulina Tragulina (also known as Traguliformes) is an infraorder of even-toed ungulates. Only the chevrotains survive to the present, including the genera '' Tragulus'' (the mouse deer) and ''Hyemoschus'', all within the family Tragulidae. Taxonomy and ...
(of which
Tragulidae The asterisk ( ), from Late Latin , from Ancient Greek , ''asteriskos'', "little star", is a typographical symbol. It is so called because it resembles a conventional image of a heraldic star. Computer scientists and mathematicians often v ...
is the only surviving
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
). Pecora's placement within
Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...
can be represented in the following
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
:(see e.g. Fig S10) Current attempts to determine the relationships among pecoran families (as well as all artiodactyls) rely on molecular studies, as little consensus exists in morphological studies. Different families within Pecora are recognized as valid by different groups of scientists.and sources therein, pp. 4–5 Until the beginning of the 21st century it was understood that the family
Moschidae Moschidae is a family of pecoran even-toed ungulates, containing the musk deer (''Moschus'') and its extinct relatives. They are characterized by long 'saber teeth' instead of horns, antlers or ossicones, modest size (''Moschus'' only reaches ; ...
(musk deer) was
sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a family, familial relationship, it is sometimes used endearingly to r ...
to
Cervidae Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
. However, a 2003
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
study by Alexandre Hassanin (of
National Museum of Natural History, France The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...
) and colleagues, based on
mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
l and
nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...
analyses, revealed that
Moschidae Moschidae is a family of pecoran even-toed ungulates, containing the musk deer (''Moschus'') and its extinct relatives. They are characterized by long 'saber teeth' instead of horns, antlers or ossicones, modest size (''Moschus'' only reaches ; ...
and
Bovidae The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, ...
form a
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
sister to
Cervidae Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
. According to the study, Cervidae diverged from the Bovidae-Moschidae clade 27 to 28 million years ago. The following
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
is based on the 2003 study. Infraorder Pecora ("horned ruminants", "higher ruminants") * Family †
Gelocidae The Gelocidae are an extinct group of hornless ruminants, ruminantia that are estimated to have lived during the Eocene and Oligocene epochs, from 36 MYA (unit), MYA to 6 MYA. The family generally includes extinct hornless ruminants which do not ...
* Family † Palaeomerycidae * Family
Cervidae Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
(
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
) * Family
Moschidae Moschidae is a family of pecoran even-toed ungulates, containing the musk deer (''Moschus'') and its extinct relatives. They are characterized by long 'saber teeth' instead of horns, antlers or ossicones, modest size (''Moschus'' only reaches ; ...
(
musk deer Musk deer can refer to any one, or all seven, of the species that make up ''Moschus'', the only extant genus of the family Moschidae. Despite being commonly called deer, they are not true deer belonging to the family Cervidae, but rather their fa ...
) * Family
Bovidae The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, ...
(
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
,
goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...
s,
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
, and
antelope The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia. Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...
s) * Superfamily
Giraffoidea Giraffoidea is a superfamily that includes the families Climacoceratidae, Antilocapridae, and Giraffidae. The only extant members in the superfamily are the pronghorn, giraffe, and okapi. The Climacoceratidae are also placed in the superfamil ...
** Family
Antilocapridae The Antilocapridae are a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids with which they comprise the superfamily Giraffoidea. Only one species, the pronghorn (''Antilocapra americana''), is ...
(
pronghorn The pronghorn (, ) (''Antilocapra americana'') is a species of artiodactyl (even-toed, hoofed) mammal indigenous to interior western and central North America. Though not an antelope, it is known colloquially in North America as the American a ...
) ** Family
Giraffidae The Giraffidae are a family of ruminant artiodactyl mammals that share a common ancestor with deer and bovids. This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant genera, the giraffe (one ...
(
giraffe The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, ''Giraffa camelopardalis ...
,
okapi The okapi (; ''Okapia johnstoni''), also known as the forest giraffe, Congolese giraffe, or zebra giraffe, is an artiodactyl mammal that is endemic to the northeast Democratic Republic of the Congo in central Africa. It is the only species ...
) ** Family †
Climacoceratidae Climacoceratidae is a family of superficially deer-like artiodactyl ungulates which lived in the Miocene epoch in Africa. They are close to the ancestry of giraffes, with some genera, such as '' Prolibytherium'', originally classified as giraffes ...


Anatomy

Pecorans share characteristics with other artiodactyls, including a four-chambered stomach, and a paraxonic foot, meaning that it supports weight on the third and fourth digits. Several characteristics distinguish Pecora from its sister taxon,
Tragulina Tragulina (also known as Traguliformes) is an infraorder of even-toed ungulates. Only the chevrotains survive to the present, including the genera '' Tragulus'' (the mouse deer) and ''Hyemoschus'', all within the family Tragulidae. Taxonomy and ...
: an
astragalus ''Astragalus'' is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to tempe ...
with parallel sides, a loss of the trapezium, and differences in parts of the skull such as the
petrosal bone The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three an ...
. The distinguishing features of most pecoran families are cranial appendages. Most modern pecorans (with the exception of the
Moschidae Moschidae is a family of pecoran even-toed ungulates, containing the musk deer (''Moschus'') and its extinct relatives. They are characterized by long 'saber teeth' instead of horns, antlers or ossicones, modest size (''Moschus'' only reaches ; ...
) have one of four types of cranial appendages: horns, antlers, ossicones, or pronghorns. * True horns have a bone core that is covered in a permanent sheath of
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
. They are indicative of Bovidae. Horns develop in the
periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structure ...
over the frontal bone, and can be curved or straight. Surface features on the keratin sheath (e.g., ridges or twists) are thought to be caused by differential rates of growth around the bone core. *
Antlers Antlers are extensions of an animal's skull found in members of the Cervidae (deer) family. Antlers are a single structure composed of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. They are generally found only on males ...
are bony structures that are shed and replaced each year in members of the family
Cervidae Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
. They grow from a permanent outgrowth of the frontal bone called the pedicle. Antlers can be branched, as in the white-tailed deer (''
Odocoileus virginianus The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
''), or palmate, as in the moose (''
Alces alces The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult ma ...
''). *
Ossicones Ossicones are columnar or conical skin-covered bone structures on the heads of giraffes, male okapi, and some of their extinct relatives. Ossicones are distinguished from the superficially similar structures of horns and antlers by their uniqu ...
are permanent bone structures that fuse to the frontal or parietal bones during the lifetime of an animal. They are found only in the
Giraffidae The Giraffidae are a family of ruminant artiodactyl mammals that share a common ancestor with deer and bovids. This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant genera, the giraffe (one ...
and closely related extinct clades, represented in modern animals by the giraffe (''
Giraffa camelopardalis The northern giraffe (''Giraffa camelopardalis''), also known as three-horned giraffe,Linnaeus, C. (1758)The Nubian or Three-horned giraffe (''Giraffa camelopardalis'').Existing Forms of Giraffe (February 16, 1897): 14. is the type species of gi ...
'') and the okapi (''
Okapia johnstoni The okapi (; ''Okapia johnstoni''), also known as the forest giraffe, Congolese giraffe, or zebra giraffe, is an artiodactyl mammal that is endemic to the northeast Democratic Republic of the Congo in central Africa. It is the monotypic taxon ...
''). *
Pronghorns The pronghorn (, ) (''Antilocapra americana'') is a species of artiodactyl (even-toed, hoofed) mammal indigenous to interior western and central North America. Though not an antelope, it is known colloquially in North America as the American an ...
are similar to horns in that they have keratinous sheaths covering permanent bone cores; however, these sheaths are deciduous and can be shed like antlers. Very little is known about the development of pronghorns, but they are generally presumed to have evolved independently. The only extant animal with pronghorns is the pronghorn antelope (''
Antilocapra americana The pronghorn (, ) (''Antilocapra americana'') is a species of artiodactyl (even-toed, hoofed) mammal indigenous to interior western and central North America. Though not an antelope, it is known colloquially in North America as the American a ...
'').


References


External links

* {{Taxonbar, from=Q772442 Ruminants Extant Burdigalian first appearances