Post by bluefedish on May 29, 2007 17:35:39 GMT -5
The terms saber-toothed tiger and saber-toothed tiger describe numerous species, mainly in the families Felidae, Hyaenodontidae, and Nimravidae, but also including two marsupial families, that lived during various parts of the Cenozoic and evolved their saber-toothed characteristics entirely independently. The saber-tooth morphology is an excellent example of convergent evolution as it occurred repeatedly and independently in at least four distinct mammalian groups.They are most known for having teeth, that were in some species up to 20 cm long and extended down from their mouth even when closed.
Saber-tooth Evolutionary Tree
All saber-tooth mammals lived between 33.7 million and 9,000 years ago, but the evolutionary lines that lead to the various saber-tooth genera started to diverge much earlier.
The lineage that led to Thylacosmilus was the first to split off, in the late Cretaceous. It is a marsupial, and thus more closely related to kangaroos and opossums than the felines. The creodonts diverged next, and then the nimravids, before the blossoming of the truly feline saber-tooths.
Class Mammalia
Subclass Marsupialia (diverged ? MYA, in the Cretaceous)
Order Sparassodonta (an extinct group of marsupial carnivores)
Family Borhyaenidae
Family Thylacosmilidae
Thylacosmilus
Subclass Placentalia
Order Creodonta (diverged ? MYA, in the Paleocene)
Family Hyaenodontidae
Hyaenodon
Boualitomus
Laekitherium
Metapterodon
Triacodon
Parvagula
Order Carnivora
Family Nimravidae (diverged from the feliforms 48–55 MYA, in the late Eocene)
Subfamily Nimravinae (Dinictis)
Subfamily Hoplophoninae
Suborder Feliformia ('cat-like' carnivores)
Family Barbourofelidae (sister taxa to Felidae)
Family Felidae (true cats)
Subfamily Machairodontinae (diverged ? MYA, in the ?)
Tribe Homotheriini
Homotherium
Machairodus
Xenosmilus
Tribe Metailurini
Dinofelis
Metailurus
Tribe Smilodontini
Megantereon
Paramachairodus
Smilodon
Selected Sources:
en.wikipedia.org/wiki/Saber-toothed_cat
Saber-tooth Evolutionary Tree
All saber-tooth mammals lived between 33.7 million and 9,000 years ago, but the evolutionary lines that lead to the various saber-tooth genera started to diverge much earlier.
The lineage that led to Thylacosmilus was the first to split off, in the late Cretaceous. It is a marsupial, and thus more closely related to kangaroos and opossums than the felines. The creodonts diverged next, and then the nimravids, before the blossoming of the truly feline saber-tooths.
Class Mammalia
Subclass Marsupialia (diverged ? MYA, in the Cretaceous)
Order Sparassodonta (an extinct group of marsupial carnivores)
Family Borhyaenidae
Family Thylacosmilidae
Thylacosmilus
Subclass Placentalia
Order Creodonta (diverged ? MYA, in the Paleocene)
Family Hyaenodontidae
Hyaenodon
Boualitomus
Laekitherium
Metapterodon
Triacodon
Parvagula
Order Carnivora
Family Nimravidae (diverged from the feliforms 48–55 MYA, in the late Eocene)
Subfamily Nimravinae (Dinictis)
Subfamily Hoplophoninae
Suborder Feliformia ('cat-like' carnivores)
Family Barbourofelidae (sister taxa to Felidae)
Family Felidae (true cats)
Subfamily Machairodontinae (diverged ? MYA, in the ?)
Tribe Homotheriini
Homotherium
Machairodus
Xenosmilus
Tribe Metailurini
Dinofelis
Metailurus
Tribe Smilodontini
Megantereon
Paramachairodus
Smilodon
Selected Sources:
en.wikipedia.org/wiki/Saber-toothed_cat
