''Smilodon'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of the extinct
machairodont
Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million until ...
subfamily of the
felid
Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the dom ...
s. It is one of the most famous
prehistoric mammal
This is an incomplete list of prehistoric mammals. It does not include extant mammals or recently extinct mammals. For extinct primate species, see: list of fossil primates.Mikko's Phylogeny Archiv
Mammaliaformes
'
*Genus †'' Adelobasileus ...
s and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related to the
tiger
The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus '' Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on u ...
or other modern cats. ''Smilodon'' lived in the
Americas
The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World.
Along with th ...
during the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch (2.5
mya – 10,000 years ago). The genus was named in 1842 based on
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s from Brazil; the generic name means "scalpel" or "two-edged knife" combined with "tooth". Three
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
are recognized today: ''S. gracilis'', ''S. fatalis'', and ''S. populator''. The two latter species were probably descended from ''S. gracilis'', which itself probably evolved from ''
Megantereon
''Megantereon'' was a genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa. It may have been the ancestor of ''Smilodon''.
Taxonomy
Fossil fragments have been found in Africa, Eurasia, and No ...
''. The hundreds of individuals obtained from the
La Brea Tar Pits
La Brea Tar Pits is an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the gro ...
in
Los Angeles
Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
constitute the largest collection of ''Smilodon'' fossils.
Overall, ''Smilodon'' was more robustly built than any
extant
Extant is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Extant taxon, a taxon which is not extinct, ...
cat, with particularly well-developed forelimbs and exceptionally long upper
canine teeth
In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...
. Its jaw had a bigger gape than that of modern cats, and its upper canines were slender and fragile, being adapted for precision killing. ''S. gracilis'' was the smallest species at in weight. ''S. fatalis'' had a weight of and height of . Both of these species are mainly known from
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, but remains from
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
have also been attributed to them. ''S. populator'' from South America was the largest species, at in weight and in height, and was among the largest known felids. The
coat
A coat typically is an outer garment for the upper body as worn by either gender for warmth or fashion. Coats typically have long sleeves and are open down the front and closing by means of buttons, zippers, hook-and-loop fasteners, toggles, a ...
pattern of ''Smilodon'' is unknown, but it has been
artistically restored with plain or spotted patterns.
In North America, ''Smilodon''
hunted large
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s such as
bison
Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised.
Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...
and
camels
A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. ...
, and it remained successful even when encountering new prey species in South America. ''Smilodon'' is thought to have killed its prey by holding it still with its forelimbs and biting it, but it is unclear in what manner the bite itself was delivered. Scientists debate whether ''Smilodon'' had a social or a solitary lifestyle; analysis of modern predator behavior as well as of ''Smilodon''s fossil remains could be construed to lend support to either view. ''Smilodon'' probably lived in closed habitats such as forests and
bush
Bush commonly refers to:
* Shrub, a small or medium woody plant
Bush, Bushes, or the bush may also refer to:
People
* Bush (surname), including any of several people with that name
**Bush family, a prominent American family that includes:
*** ...
, which would have provided cover for ambushing prey. ''Smilodon'' died out at the same time that most North and South American
megafauna
In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
disappeared, about 10,000 years ago. Its reliance on large animals has been proposed as the cause of its extinction, along with climate change and competition with other species, but the exact cause is unknown.
Taxonomy
![Lund's Smilodon populator](https://upload.wikimedia.org/wikipedia/commons/f/f8/Lund%27s_Smilodon_populator.jpg)
During the 1830s, Danish
naturalist Peter Wilhelm Lund
Peter Wilhelm Lund (14 June 1801 – 25 May 1880) was a Danish paleontologist, zoologist, and archeologist. He spent most of his life working and living in Brazil. He is considered the father of Brazilian paleontology as well as archaeology.
He ...
and his assistants
collected fossils in the
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an adje ...
caves near the small town of
Lagoa Santa, Minas Gerais
Lagoa Santa (''Holy Lagoon'') is a municipality and region in the state of Minas Gerais, Brazil. It is located 37 km north-northeast from Belo Horizonte and belongs to the mesoregion Metropolitana de Belo Horizonte and to the microregion o ...
, Brazil. Among the thousands of fossils found, he recognized a few isolated
cheek teeth as belonging to a
hyena
Hyenas, or hyaenas (from Ancient Greek , ), are feliform carnivoran mammals of the family Hyaenidae . With only four extant species (each in its own genus), it is the fifth-smallest family in the Carnivora and one of the smallest in the clas ...
, which he named ''Hyaena neogaea'' in 1839. After more material was found (including
canine teeth
In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...
and foot bones), Lund concluded the fossils instead belonged to a distinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
felid
Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the dom ...
, though transitional to the hyenas. He stated it would have matched the largest modern predators in size, and was more robust than any modern cat. Lund originally wanted to name the new genus ''
Hyaenodon
''Hyaenodon'' (" hyena-tooth") is an extinct genus of carnivorous hyaenodont mammals from tribe Hyaenodontini, within subfamily Hyaenodontinae in family Hyaenodontidae,Malcolm C. McKenna, Susan K. Bell (1997."Classification of Mammals: Above t ...
'', but realizing this had recently become preoccupied by another prehistoric predator, he instead named it ''Smilodon populator'' in 1842. He explained the
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
meaning of ''Smilodon'' as (''smilē''), "scalpel" or "two-edged knife", and ''οδόντος'' (''odóntos''), "tooth". This has also been translated as "tooth shaped like double-edged knife". He explained the species name ''populator'' as "the destroyer", which has also been translated as "he who brings devastation". By 1846, Lund had acquired nearly every part of the skeleton (from different individuals), and more specimens were found in neighboring countries by other collectors in the following years. Though some later authors used Lund's original species name ''neogaea'' instead of ''populator'', it is now considered an invalid ''
nomen nudum
In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate descr ...
'' ("naked name"), as it was not accompanied with a proper
description
Description is the pattern of narrative development that aims to make vivid a place, object, character, or group. Description is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narr ...
and no type specimens were designated.
Some South American specimens have been referred to other genera, subgenera, species, and
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
, such as ''Smilodontidion riggii'', ''Smilodon'' (''Prosmilodon'') ''ensenadensis'', and ''S. bonaeriensis'', but these are now thought to be
junior synonyms
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
* In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linn ...
of ''S. populator''.
![Smilodon fatalis holotype](https://upload.wikimedia.org/wikipedia/commons/1/13/Smilodon_fatalis_holotype.jpg)
Fossils of ''Smilodon'' were discovered in North America from the second half of the 19th century onwards. In 1869, American paleontologist
Joseph Leidy
Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist.
Leidy was professor of anatomy at the University of Pennsylvania, later was a professor of natural history at Swarthmore ...
described a
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
fragment with a
molar, which had been discovered in a petroleum bed in
Hardin County, Texas
Hardin County is a county located in the U.S. state of Texas, United States. As of the 2020 census, its population was 56,231. The county seat is Kountze. The county is named for the family of William Hardin from Liberty County, Texas.
Hardin ...
. He referred the specimen to the genus ''
Felis
''Felis'' is a genus of small and medium-sized cat species native to most of Africa and south of 60° latitude in Europe and Asia to Indochina. The genus includes the domestic cat. The smallest ''Felis'' species is the black-footed cat with a h ...
'' (which was then used for most cats, extant as well as extinct) but found it distinct enough to be part of its own
subgenus
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
, as ''F.'' (''Trucifelis'') ''fatalis''. The species name means "deadly". In an 1880 article about extinct American cats, American paleontologist
Edward Drinker Cope
Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested ...
pointed out that the ''F. fatalis'' molar was identical to that of ''Smilodon'', and he proposed the
new combination
''Combinatio nova'', abbreviated ''comb. nov.'' (sometimes ''n. comb.''), is Latin for "new combination". It is used in taxonomic biology literature when a new name is introduced based on a pre-existing name. The term should not to be confused wi ...
''S. fatalis''.
Most North American finds were scanty until excavations began in the
La Brea Tar Pits
La Brea Tar Pits is an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the gro ...
in
Los Angeles
Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
, where hundreds of individuals of ''S. fatalis'' have been found since 1875. ''S. fatalis'' has junior synonyms such as ''S. mercerii'', ''S. floridanus'', and ''S. californicus''. American paleontologist Annalisa Berta considered the holotype of ''S. fatalis'' too incomplete to be an adequate type specimen, and the species has at times been proposed to be a junior synonym of ''S. populator''.
Nordic paleontologists
Björn Kurtén Björn Olof Lennartson Kurtén (19 November 1924 – 28 December 1988) was a Finnish vertebrate paleontologist, belonging to the Swedish-speaking minority of his country.
Early life and education
Kurtén was born in Vaasa.
Career
He was a profe ...
and
Lars Werdelin
Lars Werdelin (born 1955) is a Swedish paleontologist specializing in the evolution of mammalian carnivores. One area of interest has been the evolutionary interaction of carnivores and hominins in Africa.
He received his Ph.D.
A Doctor of P ...
supported the distinctness of the two species in an article published in 1990.
A 2018 article by the American paleontologist John P. Babiarz and colleagues concluded that ''S. californicus'', represented by the specimens from the La Brea Tar Pits, was a distinct species from ''S. fatalis'' after all and that more research is needed to clarify the taxonomy of the lineage.
In his 1880 article about extinct cats, Cope also named a third species of ''Smilodon'', ''S. gracilis''. The species was based on a partial canine, which had been obtained in the
Port Kennedy Cave near the
Schuylkill River
The Schuylkill River ( , ) is a river running northwest to southeast in eastern Pennsylvania. The river was improved by navigations into the Schuylkill Canal, and several of its tributaries drain major parts of Pennsylvania's Coal Region. It fl ...
in Pennsylvania. Cope found the canine to be distinct from that of the other ''Smilodon'' species due to its smaller size and more compressed base.
Its
specific name refers to the species' lighter build. This species is known from fewer and less complete remains than the other members of the genus. ''S. gracilis'' has at times been considered part of genera such as ''
Megantereon
''Megantereon'' was a genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa. It may have been the ancestor of ''Smilodon''.
Taxonomy
Fossil fragments have been found in Africa, Eurasia, and No ...
'' and ''
Ischyrosmilus
''Homotherium'', also known as the scimitar-toothed cat or scimitar cat, is an extinct genus of machairodontine saber-toothed predator, often termed scimitar-toothed cats, that inhabited North America, South America, Eurasia, and Africa during t ...
''. ''S. populator'', ''S. fatalis'' and ''S. gracilis'' are currently considered the only valid species of ''Smilodon'', and features used to define most of their junior synonyms have been dismissed as variation between individuals of the same species (intraspecific variation).
One of the most famous of prehistoric mammals, ''Smilodon'' has often been featured in popular media and is the
state fossil
Most American states have made a state fossil designation, in many cases during the 1980s. It is common to designate one species in which fossilization has occurred, rather than a single specimen, or a category of fossils not limited to a single ...
of California.
Evolution
![Smilodon populator Dientes de Sable](https://upload.wikimedia.org/wikipedia/commons/c/c9/Smilodon_populator_Dientes_de_Sable.jpg)
Long the most completely known
saber-toothed cat
Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million until ...
, ''Smilodon'' is still one of the best-known members of the group, to the point where the two concepts have been confused. The term "saber-tooth" refers to an
ecomorph Ecomorphology or ecological morphology is the study of the relationship between the ecological role of an individual and its morphological adaptations. The term "morphological" here is in the anatomical context. Both the morphology and ecology ex ...
consisting of various groups of extinct predatory
synapsid
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...
s (mammals and close relatives), which
convergently evolved
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
extremely long
maxillary canine
In human dentistry, the maxillary canine is the tooth located laterally (away from the midline of the face) from both maxillary lateral incisors of the mouth but mesial (toward the midline of the face) from both maxillary first premolars. Both t ...
s, as well as adaptations to the skull and skeleton related to their use. This includes members of
Gorgonopsia
Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, a ...
,
Thylacosmilidae
Thylacosmilidae is an extinct Family (biology), family of metatherian predators, related to the modern marsupials, which lived in South America between the Miocene and Pliocene epochs. Like other South American mammalian predators that lived prio ...
,
Machaeroidinae
Machaeroidinae ("dagger-like") is a Family (biology), subfamily of extinct carnivorous Saber-toothed cat, sabre-toothed Placentalia, placental mammals from Asia and North America.Malcolm C. McKenna, Susan K. Bell: ''Classification of Mammals: Ab ...
,
Nimravidae
Nimravidae is an extinct family (biology), family of carnivorans, sometimes known as false saber-toothed cats, whose fossils are found in North America and Eurasia. Not considered to belong to the true cats (family Felidae), the nimravids are gen ...
,
Barbourofelidae, and
Machairodontinae
Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million until ...
. Within the family
Felidae
Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the ...
(true cats), members of the
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
Machairodontinae are referred to as saber-toothed cats, and this group is itself divided into three
tribes
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to conflic ...
:
Metailurini
Metailurini is an extinct taxonomic tribe of large saber-toothed cats that lived in Africa, Asia, Europe, and North America from the Miocene to the Pleistocene.
The best known Metalurini genera are '' Dinofelis'' and ''Metailurus''. Metailurini ...
(false saber-tooths);
Homotherini
Homotherini is an extinct tribe (or subtribe) of carnivoran mammals of the family Felidae (true cats). The tribe is commonly known as scimitar-toothed cats. These saber-toothed cats were distributed en North America, Europe, Asia, Africa, and So ...
(
scimitar
A scimitar ( or ) is a single-edged sword with a convex curved blade associated with Middle Eastern, South Asian, or North African cultures. A European term, ''scimitar'' does not refer to one specific sword type, but an assortment of different ...
-toothed cats); and
Smilodontini
Smilodontini is an extinct tribe within the Machairodontinae or "saber-toothed cat" subfamily of the Felidae. The tribe is also known as the "dirk-toothed cats". They were endemic to South America, North America, Europe, Asia, and Africa during t ...
(
dirk
A dirk is a long bladed thrusting dagger.Chisholm, Hugh (ed.), ''Dagger'', The Encyclopædia Britannica, 11th ed., Vol. VII, New York, NY: Cambridge University Press (1910), p. 729 Historically, it gained its name from the Highland Dirk (Scot ...
-toothed cats), to which ''Smilodon'' belongs. Members of Smilodontini are defined by their long slender canines with fine to no
serration
Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied p ...
s, whereas Homotherini are typified by shorter, broad, and more flattened canines, with coarser serrations. Members of Metailurini were less specialized and had shorter, less flattened canines, and are not recognized as members of Machairodontinae by some researchers.
![Smilodon tooth](https://upload.wikimedia.org/wikipedia/commons/4/4b/Smilodon_tooth.jpg)
The earliest felids are known from the
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
of Europe, such as ''
Proailurus
''Proailurus'' is an extinct felid genus that lived in Europe and Asia approximately 25 million years ago in the Late Oligocene and Miocene. Fossils have been found in Mongolia, Germany, and Spain.
Etymology
The generic name ''Proailurus'' comes ...
'', and the earliest one with saber-tooth features is the
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 ...
genus ''
Pseudaelurus
''Pseudaelurus'' is a prehistoric cat that lived in Europe, Asia and North America in the Miocene between approximately twenty and eight million years ago. It is considered to be a paraphyletic grade ancestral to living felines and pantherines a ...
''. The skull and mandible morphology of the earliest saber-toothed cats was similar to that of the modern
clouded leopards (''Neofelis''). The lineage further adapted to the precision killing of large animals by developing elongated canine teeth and wider gapes, in the process sacrificing high
bite force
Bite force quotient (BFQ) is a numerical value commonly used to represent the bite force of an animal, while also taking factors like the animal's size into account.
The BFQ is calculated as the regression of the quotient
In arithmetic, a ...
. As their canines became longer, the bodies of the cats became more robust for immobilizing prey. In
derived
Derive may refer to:
* Derive (computer algebra system), a commercial system made by Texas Instruments
* ''Dérive'' (magazine), an Austrian science magazine on urbanism
*Dérive, a psychogeographical concept
See also
*
*Derivation (disambiguatio ...
smilodontins and homotherins, the
lumbar
In tetrapod anatomy, lumbar is an adjective that means ''of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum.''
The lumbar region is sometimes referred to as the lower spine, or as an area of the back i ...
region of the spine and the tail became shortened, as did the hind limbs. Based on
mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
sequences
extracted from fossils, the lineages of ''
Homotherium
''Homotherium'', also known as the scimitar-toothed cat or scimitar cat, is an extinct genus of machairodontine saber-toothed predator, often termed scimitar-toothed cats, that inhabited North America, South America, Eurasia, and Africa during ...
'' and ''Smilodon'' are estimated to have diverged about 18 Ma ago.
The earliest species of ''Smilodon'' is ''S. gracilis'', which existed from 2.5
million
One million (1,000,000), or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian ''millione'' (''milione'' in modern Italian), from ''mille'', "thousand", plus the au ...
to 500,000 years ago (early
Blancan
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years Before Present, BP, a period of . to
Irvingtonian
The Irvingtonian North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), spanning from 1.9 million – 250,000 years BP.[ ...]
ages) and was the successor in North America of ''Megantereon'', from which it probably evolved. ''Megantereon'' itself had entered North America from
Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
during the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58[Early Pleistocene
The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...](_blank)
as part of the
Great American Interchange
The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which lan ...
.
''S. fatalis'' existed 1.6 million–10,000 years ago (late Irvingtonian to
Rancholabrean
The Rancholabrean North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from less than 240,000 years to 11,000 years BP, a p ...
ages), and replaced ''S. gracilis'' in North America.
''S. populator'' existed 1 million–10,000 years ago (
Ensenadan
The Ensenadan age is a period of geologic time (1.2–0.8 Ma) within the Early Pleistocene epoch of the Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the ...
to
Lujanian
The Lujanian age is a South American land mammal age within the Pleistocene and Holocene epochs of the Neogene, from 0.8–0.011 Ma or 800–11 tya. It follows the Ensenadan.
The age is usually divided into the middle Pleistocene Bonaerian stag ...
ages); it occurred in the eastern parts of South America.
Despite the colloquial name "saber-toothed tiger", ''Smilodon'' is not closely related to the modern
tiger
The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus '' Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on u ...
(which belongs in the subfamily
Pantherinae
Pantherinae is a subfamily within the family Felidae; it was named and first described by Reginald Innes Pocock in 1917 as only including the ''Panthera'' species. The Pantherinae genetically diverged from a common ancestor between and .
Char ...
), or any other extant felid. A 1992 ancient DNA analysis suggested that ''Smilodon'' should be grouped with modern cats (subfamilies
Felinae
The Felinae are a subfamily of the family Felidae. This subfamily comprises the small cats having a bony hyoid, because of which they are able to purr but not roar.
Other authors have proposed an alternative definition for this subfamily: as c ...
and Pantherinae). A 2005 study found that ''Smilodon'' belonged to a separate lineage.
A study published in 2006 confirmed this, showing that the Machairodontinae diverged early from the ancestors of modern cats and were not closely related to any living species. 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 ...
based on fossils and DNA analysis shows the placement of ''Smilodon'' among extinct and extant felids, after Rincón and colleagues, 2011:
Description
![Wiki Smilodon Size](https://upload.wikimedia.org/wikipedia/commons/c/cb/Wiki_Smilodon_Size.svg)
''Smilodon'' was around the size of modern
big cat
The term "big cat" is typically used to refer to any of the five living members of the genus '' Panthera'', namely the tiger, lion, jaguar, leopard, and snow leopard.
Despite enormous differences in size, various cat species are quite similar ...
s, but was more robustly built. It had a reduced
lumbar region
In tetrapod anatomy, lumbar is an adjective that means ''of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum.''
The lumbar region is sometimes referred to as the lower spine, or as an area of the back ...
, high
scapula
The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...
, short tail, and broad limbs with relatively short feet.
''Smilodon'' is most famous for its relatively long canine teeth, which are the longest found in the saber-toothed cats, at about long in the largest species, ''S.populator''.
The canines were slender and had fine serrations on the front and back side.
The skull was robustly proportioned and the
muzzle was short and broad. The
cheek bones (zygomata) were deep and widely arched, the
sagittal crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptiona ...
was prominent, and the
frontal region was slightly convex. The mandible had a flange on each side of the front. The upper incisors were large, sharp, and slanted forwards. There was a
diastema
A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition ...
(gap) between the incisors and molars of the mandible. The lower incisors were broad, recurved, and placed in a straight line across. The p3
premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
tooth of the mandible was present in most early specimens, but lost in later specimens; it was only present in 6% of the La Brea sample.
There is some dispute over whether ''Smilodon'' was
sexually dimorphic
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
. Some studies of ''S. fatalis'' fossils have found little difference between the sexes.
Conversely, a 2012 study found that, while fossils of ''S. fatalis'' show less variation in size among individuals than modern ''Panthera'', they do appear to show the same difference between the sexes in some traits.
![Smilodon Knight](https://upload.wikimedia.org/wikipedia/commons/4/4f/Smilodon_Knight.jpg)
''S. gracilis'' was the smallest species, estimated at in weight, about the size of a
jaguar
The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus '' Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in the Americas and the th ...
. It was similar to its predecessor ''Megantereon'' of the same size, but its dentition and skull were more advanced, approaching ''S. fatalis''.
''S. fatalis'' was intermediate in size between ''S. gracilis'' and ''S. populator''.
It ranged from .
and reached a shoulder height of and body length of .
It was similar to a lion in dimensions, but was more robust and muscular, and therefore had a larger body mass. Its skull was also similar to that of ''Megantereon'', though more massive and with larger canines. ''S. populator'' was among the
largest known felids, with a body mass range of ,
and one estimate suggesting up to .
A particularly large ''S. populator'' skull from Uruguay measuring in length indicates this individual may have weighed as much as .
It stood at a shoulder height of .
Compared to ''S. fatalis'', ''S. populator'' was more robust and had a more elongated and narrow skull with a straighter upper profile, higher positioned
nasal bones, a more vertical
occiput
The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...
, more massive
metapodial Metapodials are long bones of the hand (metacarpals) and feet (metatarsal
The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. ...
s and slightly longer forelimbs relative to hindlimbs.
Large tracks from Argentina (for which the
ichnotaxon
An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...
name ''Smilodonichium'' has been proposed) have been attributed to ''S. populator'', and measure by . This is larger than tracks of the
Bengal tiger
The Bengal tiger is a population of the ''Panthera tigris tigris'' subspecies. It ranks among the biggest wild cats alive today. It is considered to belong to the world's charismatic megafauna.
The tiger is estimated to have been present in ...
, to which the footprints have been compared.
![Smilodon fatalis](https://upload.wikimedia.org/wikipedia/commons/1/1c/Smilodon_fatalis.jpg)
Traditionally, saber-toothed cats have been
artistically restored with external features similar to those of extant felids, by artists such as
Charles R. Knight
Charles Robert Knight (October 21, 1874 – April 15, 1953) was an American wildlife and paleoartist best known for his detailed paintings of dinosaurs and other prehistoric animals. His works have been reproduced in many books and are currently ...
in collaboration with various paleontologists in the early 20th century. In 1969, paleontologist G. J. Miller instead proposed that ''Smilodon'' would have looked very different from a typical cat and similar to a
bulldog
The Bulldog is a British breed of dog of mastiff type. It may also be known as the English Bulldog or British Bulldog. It is of medium size, a muscular, hefty dog with a wrinkled face and a distinctive pushed-in nose.[Mauricio Antón
Mauricio Antón Ortuzar (born 1961 in Bilbao, Spain) is a paleoartist and illustrator specialized in the scientific reconstruction of extinct life, well known for his influential paintings of hominids, extinct carnivores and other vertebrate fo ...]
and coauthors disputed this in 1998 and maintained that the facial features of ''Smilodon'' were overall not very different from those of other cats. Antón noted that modern animals like the
hippopotamus
The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extan ...
are able to open their mouths extremely wide without tearing tissue due to a folded
orbicularis oris muscle
In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth.
It is a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance ...
, and such a muscle arrangement exists in modern large felids.
Antón stated that
extant phylogenetic bracketing
Phylogenetic bracketing is a method of inference used in biological sciences. It is used to infer the likelihood of unknown traits in organisms based on their position in a phylogenetic tree. One of the main applications of phylogenetic bracketing ...
(where the features of the closest extant relatives of a fossil taxon are used as reference) is the most reliable way of restoring the life-appearance of prehistoric animals, and the cat-like ''Smilodon'' restorations by Knight are therefore still accurate. A 2022 study by Antón and colleagues concluded that the upper canines of ''Smilodon'' would have been visible when the mouth was closed, while those of ''Homotherium'' would have not, after examining fossils and extant big cats.
''Smilodon'' and other saber-toothed cats have been reconstructed with both plain-colored
coats and with spotted patterns (which appears to be the ancestral condition for
feliforms
Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including cats (large and small), hyenas, mongooses, viverrids, and related taxa. Feliformia stands in contrast to the other suborder of Carnivora, Canifor ...
), both of which are considered possible. Studies of modern cat species have found that species that live in the open tend to have uniform coats while those that live in more vegetated habitats have more markings, with some exceptions. Some coat features, such as the manes of male lions or the stripes of the tiger, are too unusual to predict from fossils.
Paleobiology
Diet
![Smilodon and Canis dirus](https://upload.wikimedia.org/wikipedia/commons/3/38/Smilodon_and_Canis_dirus.jpg)
An
apex predator
An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.
Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
, ''Smilodon'' primarily hunted large mammals.
Isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
s preserved in the bones of ''S. fatalis'' in the La Brea Tar Pits reveal that
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 ...
s like bison (''
Bison antiquus
''Bison antiquus'', the antique bison or ancient bison, is an extinct species of bison that lived in Late Pleistocene North America until around 10,000 years ago. It was one of the most common large herbivores on the North American continent dur ...
'', which was much larger than the modern
American bison
The American bison (''Bison bison'') is a species of bison native to North America. Sometimes colloquially referred to as American buffalo or simply buffalo (a different clade of bovine), it is one of two extant species of bison, alongside the ...
) and camels (''
Camelops
''Camelops''Being occasionally called ''Western Camel'' or ''Yesterday's Camel''. is an extinct genus of camels that lived in North and Central America, ranging from Alaska to Guatemala, from the middle Pliocene to the end of the Pleistocene. It ...
'') were most commonly taken by the cats there.
In addition, isotopes preserved in the
tooth enamel
Tooth enamel is one of the four major Tissue (biology), tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the Crown (tooth), crown. The ...
of ''S. gracilis'' specimens from Florida show that this species fed on the
peccary
A peccary (also javelina or skunk pig) is a medium-sized, pig-like hoofed mammal of the family Tayassuidae (New World pigs). They are found throughout Central and South America, Trinidad in the Caribbean, and in the southwestern area of North ...
''
Platygonus
''Platygonus'' ("flat head" in reference to the straight shape of the forehead) is an extinct genus of herbivorous peccaries of the family Tayassuidae, endemic to North and South America from the Miocene through Pleistocene epochs (10.3 million ...
'' and the
llama
The llama (; ) (''Lama glama'') is a domesticated South American camelid, widely used as a List of meat animals, meat and pack animal by Inca empire, Andean cultures since the Pre-Columbian era.
Llamas are social animals and live with othe ...
-like ''
Hemiauchenia
''Hemiauchenia'' is a genus of laminoid camelids that evolved in North America in the Miocene period about 10 million years ago. This genus diversified and moved to South America in the Early Pleistocene, as part of the Great American Biotic In ...
''. Isotopic studies of
dire wolf
The dire wolf (''Aenocyon dirus'' ) is an extinct canine. It is one of the most famous prehistoric carnivores in North America, along with its extinct competitor ''Smilodon''. The dire wolf lived in the Americas and eastern Asia during the Late ...
(''Aenocyon dirus'') and
American lion
''Panthera atrox'', better known as the American lion, also called the North American lion, or American cave lion, is an extinct pantherine cat that lived in North America during the Pleistocene epoch and the early Holocene epoch, about 340,0 ...
(''Panthera atrox'') bones show an overlap with ''S. fatalis'' in prey, which suggests that they were competitors.
More detailed isotope analysis however, indicates that ''Smilodon fatalis'' preferred forest-dwelling prey such as tapirs, deer and forest-dwelling bison as opposed to the dire wolves' preferences for prey inhabiting open areas such as grassland. The availability of prey in the Rancho La Brea area was likely comparable to modern
East Africa
East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territories make up Eastern Africa:
Due to the historical ...
.
As ''Smilodon'' migrated to South America, its diet changed; bison were absent, the
horses
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
and
proboscidea
The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...
ns were different, and native ungulates such as
toxodonts
Toxodontia. Retrieved April 2013. is a suborder of the meridiungulate order Notoungulata. Most of the members of the five included families, including the largest notoungulates, share several dental, auditory and tarsal specializations. The g ...
and
litopterns
Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinction, extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of Meridiungulata, South American ungulates that were endemic to ...
were completely unfamiliar, yet ''S. populator'' thrived as well there as its relatives in North America. Isotopic analysis for ''Smilodon populator'' suggests that its main prey species included ''
Toxodon platensis'', ''
Pachyarmatherium
''Pachyarmatherium'' is a genus of extinct large armadillo-like cingulates found in North and South America from the Pliocene and Pleistocene epochs, related to the extant armadillos and the extinct pampatheres and glyptodonts. It was presen ...
'', ''
Holmesina
''Holmesina'' is a genus of pampathere, an extinct group of armadillo-like creatures that were distantly related to extant armadillos. Like armadillos, and unlike the other extinct branch of megafaunal cingulates, the glyptodonts, the shell wa ...
'', species of the genus ''
Panochthus
''Panochthus'' is an extinct genus of glyptodont, which lived in the Gran Chaco- Pampean region of Argentina ( Lujan, Yupoí and Agua Blanca Formations), Brazil ( Jandaíra Formation), Bolivia (Tarija and Ñuapua Formations), Paraguay and Urug ...
'', ''
Palaeolama
''Palaeolama'' () is an extinct genus of laminoid camelid that existed from the Late Pliocene to the Early Holocene (). Their range extended from North America to the intertropical region of South America.
Description
''Palaeolama'' were relat ...
'', ''
Catonyx
''Catonyx'' is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Pliocene and Pleistocene epochs. It lived from 2.5 Ma to about 10,000 years ago, existing for approximately . The most recent dat ...
'', ''
Equus neogeus'', and the crocodilian ''
Caiman latirostris''. This analysis of its diet also indicates that ''S. populator'' hunted both in open and forested habitats. The differences between the North and South American species may be due to the difference in prey between the two continents.
''Smilodon'' may have avoided eating bone and would have left enough food for scavengers. However,
coprolite
A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is de ...
s assigned to ''S. populator'' recovered from Argentina preserve ''
Mylodon
''Mylodon'' is a genus of extinct ground sloth belonging to the family Mylodontidae, known from the region of Patagonia in Chile and Argentina in southern South America. With a total length of 3 to 4 m, it is one of the best-known and largest re ...
''
osteoderms
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct ...
and a ''
Lama
Lama (; "chief") is a title for a teacher of the Dharma in Tibetan Buddhism. The name is similar to the Sanskrit term ''guru'', meaning "heavy one", endowed with qualities the student will eventually embody. The Tibetan word "lama" means "hi ...
'' scaphoid bone. In addition to this unambiguous evidence of bone consumption, the coprolites suggest that ''Smilodon'' had a more generalist diet than previously thought. Examinations of dental microwear from La Brea further suggests that ''Smilodon'' consumed both flesh and bone. ''Smilodon'' itself may have scavenged dire wolf kills. It has been suggested that ''Smilodon'' was a pure scavenger that used its canines for display to assert dominance over carcasses, but this theory is not supported today as no modern terrestrial mammals are pure scavengers.
Predatory behavior
![Felipeda miramarensis huellas de smilodon](https://upload.wikimedia.org/wikipedia/commons/8/8d/Felipeda_miramarensis_huellas_de_smilodon.jpg)
The
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
of ''Smilodon'' had
sulcal patterns similar to modern cats, which suggests an increased complexity of the regions that control the sense of hearing, sight, and coordination of the limbs. Felid saber-tooths in general had relatively small
eyes
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conve ...
that were not as forward-facing as those of modern cats, which have good
binocular vision
In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...
to help them move in trees. ''Smilodon'' was likely an
ambush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture or trap prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey us ...
that concealed itself in dense vegetation, as its limb proportions were similar to modern forest-dwelling cats, and its short tail would not have helped it balance while running. Unlike its ancestor ''Megantereon'', which was at least partially
scansorial and therefore able to climb trees, ''Smilodon'' was probably completely terrestrial due to its greater weight and lack of climbing adaptations.
Tracks from Argentina named ''Felipeda miramarensis'' in 2019 may have been produced by ''Smilodon''. If correctly identified, the tracks indicate that the animal had fully retractible claws,
plantigrade
151px, Portion of a human skeleton, showing plantigrade habit
In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. T ...
feet, lacked strong
supination
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...
capabilities in its paws, notably robust forelimbs compared to the hindlimbs, and was probably an ambush predator.
The
heel bone
In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock.
St ...
of ''Smilodon'' was fairly long, which suggests it was a good jumper.
Its well-developed flexor and extensor muscles in its
forearm
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anat ...
s probably enabled it to pull down, and securely hold down, large prey. Analysis of the cross-sections of ''S. fatalis''
humeri
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a round ...
indicated that they were strengthened by
cortical thickening to such an extent that they would have been able to sustain greater loading than those of extant big cats, or of the extinct American lion. The thickening of ''S. fatalis''
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
s was within the range of extant felids.
[ ] Its canines were fragile and could not have bitten into bone; due to the risk of breaking, these cats had to subdue and restrain their prey with their powerful forelimbs before they could use their canine teeth, and likely used quick slashing or stabbing bites rather than the slow, suffocating bites typically used by modern cats.
On rare occasions, as evidenced by fossils, ''Smilodon'' was willing to risk biting into bone with its canines. This may have been focused more towards competition such as other ''Smilodon'' or potential threats such as other carnivores than on prey.
![Smilodon bite](https://upload.wikimedia.org/wikipedia/commons/2/2a/Smilodon_bite.png)
Debate continues as to how ''Smilodon'' killed its prey. Traditionally, the most popular theory is that the cat delivered a deep stabbing bite or open-jawed stabbing thrust to the throat, killing the prey very quickly.
Another hypothesis suggests that ''Smilodon'' targeted the belly of its prey. This is disputed, as the curvature of their prey's belly would likely have prevented the cat from getting a good bite or stab. In regard to how ''Smilodon'' delivered its bite, the "canine shear-bite" hypothesis has been favored, where flexion of the neck and rotation of the skull assisted in biting the prey, but this may be mechanically impossible. However, evidence from comparisons with ''Homotherium'' suggest that ''Smilodon'' was fully capable of and utilized the canine shear-bite as its primary means of killing prey, based on the fact that it had a thick skull and relatively little trabecular bone, while ''Homotherium'' had both more trabecular bone and a more lion-like clamping bite as its primary means of attacking prey. The discovery, made by Figueirido and Lautenschlager ''et al.,'' published in 2018 suggests extremely different ecological adaptations in both machairodonts. The mandibular flanges may have helped resist bending forces when the mandible was pulled against the hide of a prey animal.
[ ]
The protruding incisors were arranged in an arch, and were used to hold the prey still and stabilize it while the canine bite was delivered. The contact surface between the canine crown and the gum was enlarged, which helped stabilize the tooth and helped the cat sense when the tooth had penetrated to its maximum extent. Since saber-toothed cats generally had a relatively large
infraorbital foramen
In human anatomy, the infraorbital foramen is one of two small holes in the skull's upper jawbone (maxillary bone), located below the eye socket and to the left and right of the nose. Both holes are used for blood vessels and nerves. In anatomica ...
(opening) in the skull, which housed nerves associated with the whiskers, it has been suggested the improved senses would have helped the cats' precision when biting outside their field of vision, and thereby prevent breakage of the canines. The blade-like
carnassial
Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...
teeth were used to cut skin to access the meat, and the reduced molars suggest that they were less adapted for crushing bones than modern cats. As the food of modern cats enters the mouth through the side while cutting with the carnassials, not the front incisors between the canines, the animals do not need to gape widely, so the canines of ''Smilodon'' would likewise not have been a hindrance when feeding.
A study published in 2022 of how machairodonts fed revealed that wear patterns on the teeth of ''S. fatalis'' also suggest that it was capable of eating bone to a similar extent as lions. This and comparisons with bite marks left by the contemporary machairodont ''
Xenosmilus
''Xenosmilus hodsonae'' (from Greek, , ''xenos'', "strange" + , ''smilē'', " chisel" ) is an extinct species of the Machairodontinae, or saber-toothed cats.
Description
The species name ''hodsonae'' originates from Debra Hodson, the wife of ...
'' suggest that ''Smilodon'' and its relatives could efficiently de-flesh a carcass of meat when feeding without being hindered by their long canines.
Despite being more powerfully built than other large cats, ''Smilodon'' had a weaker bite. Modern big cats have more pronounced
zygomatic arch
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomati ...
es, while these were smaller in ''Smilodon'', which restricted the thickness and therefore power of the
temporalis muscle
In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa, superior to the zygomati ...
s and thus reduced ''Smilodon''s bite force. Analysis of its narrow jaws indicates that it could produce a bite only a third as strong as that of a lion (the bite force quotient measured for the lion is 112).
There seems to be a general rule that the saber-toothed cats with the largest canines had proportionally weaker bites. Analyses of canine
bending strength (the ability of the canine teeth to resist bending forces without breaking) and bite forces indicate that the saber-toothed cats' teeth were stronger relative to the bite force than those of modern big cats. In addition, ''Smilodon'' gape could have reached over 110 degrees, while that of the modern lion reaches 65 degrees. This made the gape wide enough to allow ''Smilodon'' to grasp large prey despite the long canines.
A 2018 study compared the killing behavior of ''Smilodon fatalis'' and ''Homotherium serum'', and found that the former had a strong skull with little
trabecular bone
A trabecula (plural trabeculae, from Latin for "small beam") is a small, often microscopic, tissue element in the form of a small beam, strut or rod that supports or anchors a framework of parts within a body or organ. A trabecula generally has ...
for a stabbing canine-shear bite, whereas the latter had more trabecular bone and used a clamp and hold style more similar to lions. The two would therefore have held distinct ecological niches.
Natural traps
Many ''Smilodon'' specimens have been excavated from
asphalt seeps that acted as natural carnivore traps. Animals were accidentally trapped in the seeps and became bait for predators that came to scavenge, but these were then trapped themselves. The best-known of such traps are at La Brea in Los Angeles, which have produced over 166,000 ''Smilodon fatalis'' specimens that form the largest collection in the world. The sediments of the pits there were accumulated 40,000 to 10,000 years ago, in the
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
. Though the trapped animals were buried quickly, predators often managed to remove limb bones from them, but they were themselves often trapped and then scavenged by other predators; 90% of the excavated bones belonged to predators.
The Talara Tar Seeps in Peru represent a similar scenario, and have also produced fossils of ''Smilodon''. Unlike in La Brea, many of the bones were broken or show signs of weathering. This may have been because the layers were shallower, so the thrashing of trapped animals damaged the bones of previously trapped animals. Many of the carnivores at Talara were juveniles, possibly indicating that inexperienced and less fit animals had a greater chance of being trapped. Though Lund thought accumulations of ''Smilodon'' and herbivore fossils in the Lagoa Santa Caves were due to the cats using the caves as dens, these are probably the result of animals dying on the surface, and water currents subsequently dragging their bones to the floor of the cave, but some individuals may also have died after becoming lost in the caves.
Social life
![La Brea Tar Pits](https://upload.wikimedia.org/wikipedia/commons/c/c1/La_Brea_Tar_Pits.jpg)
Scientists debate whether ''Smilodon'' was
social
Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not.
Etymology
The word "social" derives from ...
. One study of African predators found that social predators like
lion
The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
s and
spotted hyena
The spotted hyena (''Crocuta crocuta''), also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus ''Crocuta'', native to sub-Saharan Africa. It is listed as being of least concern by the IUC ...
s respond more to the
distress call
A distress signal, also known as a distress call, is an internationally recognized means for obtaining help. Distress signals are communicated by transmitting radio signals, displaying a visually observable item or illumination, or making a soun ...
s of prey than solitary species. Since ''S. fatalis'' fossils are common at the La Brea Tar Pits, and were likely attracted by the distress calls of stuck prey, this could mean that this species was social as well. One critical study claims that the study neglects other factors, such as body mass (heavier animals are more likely to get stuck than lighter ones), intelligence (some social animals, like the American lion, may have avoided the tar because they were better able to recognize the hazard), lack of visual and
olfactory
The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.
In humans, it ...
lures, the type of audio lure, and the length of the distress calls (the actual distress calls of the trapped prey animals would have lasted longer than the calls used in the study). The author of that study ponders what predators would have responded if the recordings were played in India, where the otherwise solitary tigers are known to aggregate around a single carcass. The authors of the original study responded that though effects of the calls in the tar pits and the playback experiments would not be identical, this would not be enough to overturn their conclusions. In addition, they stated that weight and intelligence would not likely affect the results as lighter carnivores are far more numerous than heavy herbivores and the social (and seemingly intelligent) dire wolf is also found in the pits.
![Lions hunting a buffalo](https://upload.wikimedia.org/wikipedia/commons/3/3d/Lions_hunting_a_buffalo.jpg)
Another argument for sociality is based on the healed injuries in several ''Smilodon'' fossils, which would suggest that the animals needed others to provide them food.
This argument has been questioned, as cats can recover quickly from even severe bone damage and an injured ''Smilodon'' could survive if it had access to water.
However, a ''Smilodon'' suffering hip dysplasia at a young age that survived to adulthood suggests that it could not have survived to adulthood without aid from a social group, as this individual was unable to hunt or defend its territory due to the severity of its congenital issue. The brain of ''Smilodon'' was relatively small compared to other cat species. Some researchers have argued that ''Smilodon'' brain would have been too small for it to have been a social animal.
An analysis of brain size in living big cats found no correlation between brain size and sociality. Another argument against ''Smilodon'' being social is that being an ambush hunter in closed habitat would likely have made group-living unnecessary, as in most modern cats.
Yet it has also been proposed that being the largest predator in an environment comparable to the savanna of Africa, ''Smilodon'' may have had a social structure similar to modern lions, which possibly live in groups primarily to defend optimal territory from other lions (lions are the only social big cats today).
Whether ''Smilodon'' was sexually dimorphic has implications for its reproductive behavior. Based on their conclusions that ''Smilodon fatalis'' had no sexual dimorphism, Van Valkenburgh and Sacco suggested in 2002 that, if the cats were social, they would likely have lived in
monogamous pairs (along with offspring) with no intense competition among males for females.
Likewise, Meachen-Samuels and Binder concluded in 2010 that aggression between males was less pronounced in ''S. fatalis'' than in the American lion.
Christiansen and Harris found in 2012 that, as ''S. fatalis'' did exhibit some sexual dimorphism, there would have been evolutionary selection for competition between males.
Some bones show evidence of having been bitten by other ''Smilodon'', possibly the result of territorial battles, competition for breeding rights or over prey. Two ''S. populator'' skulls from Argentina show seemingly fatal, unhealed wounds which appear to have been caused by the canines of another ''Smilodon'' (though it cannot be ruled out they were caused by kicking prey). If caused by intraspecific fighting, it may also indicate that they had social behavior which could lead to death, as seen in some modern felines (as well as indicating that the canines could penetrate bone).
It has been suggested that the exaggerated canines of saber-toothed cats evolved for
sexual display
A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate Mate choice, exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ( ...
and competition, but a statistical study of the correlation between canine and body size in ''S. populator'' found no difference in scaling between body and canine size concluded it was more likely they evolved solely for a predatory function.
A set of three associated skeletons of ''S. fatalis'' found in Ecuador and described in 2021 by Reynolds, Seymour, and Evans suggests that there was prolonged parental care in ''Smilodon''. The two subadult individuals uncovered share a unique inherited trait in their dentaries, suggesting they were siblings; a rare instance of familial relationships being found in the fossil record. The subadult specimens are also hypothesized to have been male and female, respectively, while the adult skeletal remains found at the site are believed to have belonged to their mother. The subadults were estimated to have been around two years of age at the time of their deaths, but were still growing.
The structure of the
hyoid bones suggest that ''Smilodon'' could
roar like modern big cats, which may have implications for their social life.
Development
![Smilodon canine replacement](https://upload.wikimedia.org/wikipedia/commons/1/15/Smilodon_canine_replacement.jpg)
''Smilodon'' started developing its adult saber-teeth when the animal reached between 12 and 19 months of age, shortly after the completion of the eruption of the cat's
baby teeth
Deciduous teeth or primary teeth, also informally known as baby teeth, milk teeth, or temporary teeth,Illustrated Dental Embryology, Histology, and Anatomy, Bath-Balogh and Fehrenbach, Elsevier, 2011, page 255 are the first set of teeth in the ...
. Both baby and adult canines would be present side by side in the mouth for an approximately 11-month period, and the muscles used in making the powerful bite were developed at about one-and-a-half years old as well, eight months earlier than in a modern lion. After ''Smilodon'' reached 23 to 30 months of age, the infant teeth were shed while the adult canines grew at an average growth rate of per month during a 12-month period. They reached their full size at around 3 years of age, later than modern species of big cats. Juvenile and adolescent ''Smilodon'' specimens are extremely rare at Rancho La Brea, where the study was performed, indicating that they remained hidden or at denning sites during hunts, and depended on parental care while their canines were developing.
[ ]
A 2017 study indicates that juveniles were born with a robust build similar to the adults. Comparison of the bones of juvenile ''S. fatalis'' specimens from La Brea with those of the contemporaneous American lion revealed that the two cats shared a similar growth curve. Felid forelimb development during
ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...
(changes during growth) has remained tightly constrained. The curve is similar to that for modern cats such as tigers and cougars, but shifts more towards the robust direction of the axes than is seen in modern felids. Examinations by Reynolds, Seymour, and Evans (2021) suggest that ''Smilodon'' had a unique and fast growth rate similar to a tiger, but that there was a prolonged period of growth in the genus similar to what is seen in lions, and that the cubs were reliant on their parents until this growth period ended.
Paleopathology
Several ''Smilodon'' fossils show signs of
ankylosing spondylitis
Ankylosing spondylitis (AS) is a type of arthritis characterized by long-term inflammation of the joints of the spine typically where the spine joins the pelvis. Occasionally areas affected may include other joints such as the shoulders or hip ...
,
hyperostosis
Hyperostosis is an excessive growth of bone. It may lead to exostosis. It occurs in many musculoskeletal disorders.
See also
* Diffuse idiopathic skeletal hyperostosis
Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characteri ...
and trauma.
One study of 1,000 ''Smilodon'' skulls found that 36% of them had eroded
parietal bone
The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
s, which is where the largest jaw muscles attach. They also showed signs of microfractures, and the weakening and thinning of bones possibly caused by mechanical stress from the constant need to make stabbing motions with the canines. Bony growths where the
deltoid muscle
The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle appears to be made up o ...
inserted in the humerus is a common pathology for a La Brea specimen, which was probably due to repeated strain when ''Smilodon'' attempted to pull down prey with its forelimbs. Sternum injuries are also common, probably due to collision with prey. The frequency of trauma in ''S. fatalis'' specimens was 4.3%, compared to 2.8% in the dire wolf, which implies the ambush predatory behavior of the former led to greater risk of injury than the pursuit predatory behavior of the latter. ''Smilodon'' remains exhibit relatively more shoulder and
lumbar vertebrae
The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...
injuries.
Distribution and habitat
![Smilodon skeleton and Felis atrox skull](https://upload.wikimedia.org/wikipedia/commons/5/50/Smilodon_skeleton_and_Felis_atrox_skull.JPG)
''Smilodon'' lived during the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch (2.5 mya–10,000 years ago), and was perhaps the most recent of the saber-toothed cats.
It probably lived in closed habitat such as forest or
bush
Bush commonly refers to:
* Shrub, a small or medium woody plant
Bush, Bushes, or the bush may also refer to:
People
* Bush (surname), including any of several people with that name
**Bush family, a prominent American family that includes:
*** ...
. Fossils of the genus have been found throughout the Americas.
The northernmost remains of the genus are ''S. fatalis'' fossils from
Alberta, Canada
Alberta ( ) is one of the thirteen provinces and territories of Canada, provinces and territories of Canada. It is part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to t ...
.
The habitat of North America varied from subtropical forests and savannah in the south, to treeless
mammoth steppes
During the Last Glacial Maximum, the mammoth steppe, also known as steppe-tundra, was the Earth's most extensive biome. It spanned from Spain eastward across Eurasia to Canada and from the List of islands in the Arctic Ocean, arctic islands sout ...
in the north. The mosaic vegetation of woods, shrubs, and grasses in southwestern North America supported large herbivores such as horses, bison,
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 ...
,
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 ...
, camels,
mammoth
A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...
s,
mastodon
A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...
s, and
ground sloth
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...
s. North America also supported other saber-toothed cats, such as ''Homotherium'' and ''Xenosmilus'', as well as other large carnivores including dire wolves,
short-faced bear
The Tremarctinae or short-faced bears is a subfamily of Ursidae that contains one living representative, the spectacled bear (''Tremarctos ornatus'') of South America, and several extinct species from four genera: the Florida spectacled bear ('' ...
(''Arctodus simus'') and the American lion.
Competition from such carnivores may have prevented North American ''S. fatalis'' from attaining the size of South America's ''S. populator''. The similarity in size of ''S. fatalis'' and the American lion suggests niche overlap and direct competition between these species, and they appear to have fed on similarly sized prey.
''S. gracilis'' entered South America during the early to middle Pleistocene, where it probably gave rise to ''S. populator'', which lived in the eastern part of the continent. ''S. fatalis'' also entered western South America in the late Pleistocene, and the two species were thought to be divided by the
Andes mountains
The Andes, Andes Mountains or Andean Mountains (; ) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range i ...
.
However, in 2018, a skull of ''S. fatalis'' found in
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
east of the Andes was reported, which puts the idea that the two species were
allopatric
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
(geographically separated) into question.
The American interchange resulted in a mix of native and
invasive species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
sharing the prairies and woodlands in South America; North American herbivores included proboscideans, horses,
camelid
Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, ...
s and deer, South American herbivores included toxodonts, litopterns, ground sloths, and glyptodonts. Native
metatherian
Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well ...
predators (including the saber-toothed
thylacosmilid
Thylacosmilidae is an extinct family of metatherian predators, related to the modern marsupials, which lived in South America between the Miocene and Pliocene epochs. Like other South American mammalian predators that lived prior to the Great A ...
s) had gone extinct by the Pliocene, and were replaced by North American carnivores such as canids, bears, and large cats.
''S. populator'' was very successful, while ''Homotherium'' never became widespread in South America. The extinction of the thylacosmilids has been attributed to competition with ''Smilodon'', but this is probably incorrect, as they seem to have disappeared before the arrival of the large cats. The
phorusrhacid
Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...
"terror birds" may have dominated the large predator niche in South America until ''Smilodon'' arrived. ''S. populator'' may have been able to reach larger size than ''S. fatalis'' due to a lack of competition in Pleistocene South America; ''S. populator'' arrived after the extinction of ''
Arctotherium angustidens'', one of the largest carnivores ever, and could therefore assume the niche of mega-carnivore.
[Sherani, S. (2016). ''A new specimen-dependent method of estimating felid body mass (No. e2327v2)''. PeerJ Preprints.] ''S. populator'' preferred large prey from open habitats such as grassland and plains, based on evidence gathered from isotope ratios that determined the animal's diet. In this way, the South American ''Smilodon'' species was probably similar to the modern lion. ''S. populator'' probably competed with the canid ''
Protocyon
''Protocyon'' is an extinct genus of large canid endemic to South and North America during the Late Pleistocene living from 781 to 12thousand years ago.
Description
''Protocyon'' was a hypercarnivore, suggested by its dental adaptations. Like ma ...
'' there, but not with the jaguar, which fed primarily on smaller prey.
Extinction
![Panthera leo atrox and Smilodon fatalis Page](https://upload.wikimedia.org/wikipedia/commons/8/8b/Panthera_leo_atrox_and_Smilodon_fatalis_Page.jpg)
Along with most of the Pleistocene megafauna, ''Smilodon'' became extinct 10,000 years ago in the
Quaternary extinction event
The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
. Its extinction has been linked to the decline and extinction of large herbivores, which were replaced by smaller and more agile ones like deer. Hence, ''Smilodon'' could have been too specialized at hunting large prey and may have been unable to adapt.
A 2012 study of ''Smilodon'' tooth wear found no evidence that they were limited by food resources.
[ ] Other explanations include climate change and competition with ''
Homo sapiens
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
''
(who entered the Americas around the time ''Smilodon'' disappeared), or a combination of several factors, all of which apply to the general Pleistocene extinction event, rather than specifically to the extinction of the saber-toothed cats.
Writers of the first half of the twentieth century theorized that the last saber-toothed cats, ''Smilodon'' and ''Homotherium'', became extinct through competition with the faster and more generalized felids that replaced them. It was even proposed that the saber-toothed predators were inferior to modern cats, as the ever-growing canines were thought to inhibit their owners from feeding properly. Yet fast felids, such as the American lion and the
American cheetah
The American cheetah is either of two feline species of the extinct genus ''Miracinonyx'', endemic to North America during the Pleistocene epoch (2.6 million to 12,000 years ago) and morphologically similar to the modern cheetah (''Acinonyx j ...
(''Miracinonyx''), also became extinct during the Late Pleistocene. The fact that saber-teeth evolved many times in unrelated lineages also attests to the success of this feature.
The latest ''Smilodon fatalis'' specimen recovered from the Rancho La Brea tar pits has been dated to 13,025 years ago.
The latest ''Smilodon populator'' remains found in the cave of Cueva del Medio, near the town of Soria, northeast
Última Esperanza Province
Última Esperanza ( es, Provincia de Última Esperanza, meaning "Last Hope Province") is one of four provinces in the southern Chilean region of Magallanes and Antártica Chilena. The capital is Puerto Natales and it is named after Última Espera ...
,
Magallanes Region
The Magallanes Region (), officially the Magallanes y la Antártica Chilena Region ( es, Región de Magallanes y de la Antártica Chilena), is one of Chile's 16 first order administrative divisions. It is the southernmost, largest, and second lea ...
in southernmost
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
have been dated to 10,935–11,209 years ago. The most recent carbon-14 date for ''S. fatalis'' reported was 10,200 years BP for remains from the
First American Cave
The First American Cave is an archaeological and palentological site in downtown Nashville, Davidson County, Tennessee. The site was initially recognized in 1971 during construction of the foundations for the First American National Bank building ...
in 1971;
however, the most recent "credible" date has been given as 11,130 BP.
See also
*
List of largest carnivorans
*
List of largest prehistoric carnivorans
The largest prehistoric animals include both vertebrate and invertebrate species. Many of them are described below, along with their typical range of size (for the general dates of extinction, see the link to each). Many species mentioned might ...
*
Megafauna
In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
*
Quaternary extinction event
The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
References
Bibliography
*
{{authority control
Apex predators
Holocene extinctions
Fossil taxa described in 1842
Prehistoric carnivoran genera
Pleistocene carnivorans
Pleistocene first appearances
Pleistocene genus extinctions
Pleistocene mammals of North America
Pleistocene mammals of South America
Smilodontini
Taxa named by Peter Wilhelm Lund