A notable distinctive feature of thylacoleonids is their unusual blade-like third
premolars,[4] which functioned as the
carnassial teeth.[5] 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 590 grams (1.30 lb), while the last species of the family, the Pleistocene Thylacoleo carnifex is suggested to have had a body mass of around 160 kilograms (350 lb), comparable to a
big cat.[6] Later members of the group saw progressive reduction in the number of teeth in the jaws.[7]
Ecology
Early members of Thylacinidae 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.[8][9] Earlier species of Thylacoleonidae like Lekaneleo roskellyae are suggested to have been
omnivorous, while at least later species of Wakaleo and Thylacoleo are thought to have been
hypercarnivores.[10]
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,[11] though other authors have placed them at the base of Diprotodontia, outside of either Vombatiformes,
Phalangeriformes or
Macropodiformes.[12] Thylacoleonids are thought to have evolved from herbivorous ancestors.[5]
The family was described by
Theodore Gill in a systematic revision of mammalian taxa published by the
Smithsonian Institution in 1872.[1]
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.[7]
Classification
Five genera are currently accepted as belonging to this family:[13]
^
abcdGillespie, A. K. (2023). "Two new marsupial lion taxa (Marsupialia, Thylacoleonidae) from the early and Middle Miocene of Australia". Alcheringa: An Australasian Journal of Palaeontology: 1–16.
doi:
10.1080/03115518.2022.2152096.
S2CID256157821.