Thylacosmilus
Encyclopedia
Thylacosmilus was a genus
of sabre-toothed metatherian predators that first appeared during the Miocene
. Remains of the animal have been found in parts of South America
, primarily Argentina
. Though Thylacosmilus is one of several predatory mammal genera typically called "sabre-toothed cats", it was not a felid but a sparassodont
, a group closely related to marsupial
s, and only superficially resembled other sabre-toothed mammals due to convergent evolution
.
-like upper canines and short, blunt, peg-like lower canines. The incisor
s were missing altogether and the other teeth were severely reduced, but, as distinct from machairodont
s, their number was complete.
It is estimated to have weighed around 150 kilograms (330.7 lb). Thylacosmilus and the similarly sized Marsupial Lion
were the largest carnivorous metatherians.
Thylacosmilus sabre-teeth kept growing throughout its life, unlike those of true sabre-toothed felines. It also had a pair of elongated, scabbard
-like flanges growing from the lower jaw, which protected the sabre-teeth when it closed its mouth. The cervical vertebrae were very strong and to some extent resembled the vertebrae of machairodonts.
Thylacosmilus went extinct during the Pliocene
, a timeframe closely corresponding to the arrival of the sabre-toothed cat Smilodon
from North America
in the Great American Interchange
. Out-competition from the anatomically similar Smilodon appears to have driven the extinction, though this is not typical of other South American extinctions during the period.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sabre-toothed metatherian predators that first appeared during the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. Remains of the animal have been found in parts of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, primarily Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Though Thylacosmilus is one of several predatory mammal genera typically called "sabre-toothed cats", it was not a felid but a sparassodont
Sparassodonta
Sparassodonta is an extinct order of carnivorous metatherian mammals native to South America. They were once considered to be true marsupials, but are now thought to be a sister taxon to them. A number of these mammalian predators closely resemble placental predators that evolved separately on...
, a group closely related to marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s, and only superficially resembled other sabre-toothed mammals due to convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
.
Description
Thylacosmilus had long, sabreSabre
The sabre or saber is a kind of backsword that usually has a curved, single-edged blade and a rather large hand guard, covering the knuckles of the hand as well as the thumb and forefinger...
-like upper canines and short, blunt, peg-like lower canines. The incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s were missing altogether and the other teeth were severely reduced, but, as distinct from machairodont
Machairodontinae
Machairodontinae is an extinct carnivoran mammal subfamily of Felidae endemic to Asia, Africa, North America, South America, and Europe from the Miocene to Pleistocene living from c. 23 Ma until c...
s, their number was complete.
It is estimated to have weighed around 150 kilograms (330.7 lb). Thylacosmilus and the similarly sized Marsupial Lion
Marsupial Lion
The Marsupial Lion is an extinct species of carnivorous marsupial mammal that lived in Australia from the early to the late Pleistocene...
were the largest carnivorous metatherians.
Thylacosmilus sabre-teeth kept growing throughout its life, unlike those of true sabre-toothed felines. It also had a pair of elongated, scabbard
Scabbard
A scabbard is a sheath for holding a sword, knife, or other large blade. Scabbards have been made of many materials over the millennia, including leather, wood, and metals such as brass or steel.-Types of scabbards:...
-like flanges growing from the lower jaw, which protected the sabre-teeth when it closed its mouth. The cervical vertebrae were very strong and to some extent resembled the vertebrae of machairodonts.
Thylacosmilus went extinct during the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
, a timeframe closely corresponding to the arrival of the sabre-toothed cat Smilodon
Smilodon
Smilodon , often called a saber-toothed cat or saber-toothed tiger, is an extinct genus of machairodonts. This saber-toothed cat was endemic to North America and South America, living from near the beginning through the very end of the Pleistocene epoch .-Etymology:The nickname "saber-tooth" refers...
from North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
in the Great American Interchange
Great American Interchange
The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents...
. Out-competition from the anatomically similar Smilodon appears to have driven the extinction, though this is not typical of other South American extinctions during the period.
