Thylacoleonidae

Thylacoleonidae is a family of extinct carnivorous diprotodontian marsupials from Australia, referred to as marsupial lions. The best known is '' Thylacoleo carnifex'', also called the marsupial lion. The clade ranged from the Late Oligocene to the Late Pleistocene, with some earlier species the size of a possum, while the youngest members of the family belonging to the genus ''Thylacoleo'' reached sizes comparable to living big cats.

Description

A notable distinctive feature of thylacoleonids is their unusual blade-like third premolars, which functioned as the carnassial teeth. Thylacoleonids varied widely in body size. One of the smallest thylacoleonids, the Early Miocene '' Microleo attenboroughi'', is estimated to have had a body mass of , while the last species of the family, the Pleistocene ''Thylacoleo carnifex'' is suggested to have had a body mass of around , comparable to a big cat. Later members of the group saw progressive reduction in the number of teeth in the jaws.

Ecology

Early members of Thylacoleonidae like ''Microleo, Lekaneleo'' and early species of ''Wakaleo'' were likely arboreal tree climbing mammals, though later members of ''Wakaleo'' and '' Thylacoleo'' were likely primarily terrestrial with some climbing capabilities. Some early species of Thylacoleonidae like ''Lekaneleo roskellyae'' are suggested to have been omnivorous, with others like '' Microleo'' were likely carnivorous, feeding on small vertebrates and (to a probably small extent) insects. Species of ''Wakaleo'' and ''Thylacoleo'' are thought to have been hypercarnivores that fed on larger prey.

Taxonomy

Thylacoleontidae is considered a member of Diprotodontia, though its precise position within that group is uncertain. They have often been considered a basal group (often the most basal group) within Vombatiformes, making their closest living relatives wombats and koalas, though other authors have placed them at the base of Diprotodontia, outside of either Vombatiformes, Phalangeriformes or Macropodiformes. Thylacoleonids are thought to have evolved from herbivorous ancestors.

The family was described by Theodore Gill in a systematic revision of mammalian taxa published by the Smithsonian Institution in 1872.
The name is derived from the genus named by Richard Owen, '' Thylacoleo'', which he recognised as a potent carnivore and described as marsupial version of the modern lions (''Leo'').

A revision of the family was published in 2017, enabled by the discovery of a skull of an early species, named as '' Wakaleo schouteni'', which allowed closer comparison with previously described species and the more complete fossil record of the lineages. The study by Anna Gillespie, Mike Archer and Suzanne Hand, revised the description of ''Wakaleo'' to include a new species and circumscribe taxa previously assigned to ''Priscileo''.

Classification

Five genera are currently accepted as belonging to this family:

* Genus '' Enigmaleo''
** ''Enigmaleo archeri'' (Early Miocene)
* Genus '' Lekaneleo''
** ''Lekaneleo myersi'' (Middle Miocene)
** ''Lekaneleo roskellyae'' (Early Miocene)
* Genus '' Microleo''
** ''Microleo attenboroughi'' (Early Miocene)
* Subfamily Thylacoleoninae
** Genus '' Thylacoleo''
*** ''Thylacoleo crassidentatus'' (Pliocene)
* Subfamily Wakaleoninae
** Genus '' Wakaleo''
*** ''Wakaleo pitikantensis'' (Late Oligocene)
*** ''Wakaleo schouteni'' (Late Oligocene—Early Miocene)
*** ''Wakaleo oldfieldi'' (Early Miocene—Late Miocene)
*** ''Wakaleo vanderleuri'' (Middle Miocene—Late Miocene)
*** ''Wakaleo alcootaensis'' (Late Miocene)
Cladogram after Gillespie (2023):

References

{{Taxonbar, from=Q693481

Prehistoric vombatiforms
Carnivorous marsupials
Prehistoric mammals of Australia
Chattian first appearances
Pleistocene extinctions
Prehistoric mammal families