Thylacoleonidae is a family of extinctcarnivorousdiprotodontian marsupials from Australia, referred to as marsupial lions.[2] The best known is Thylacoleo carnifex, also called the marsupial lion.[3] 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
Illustration of lower dentition of Thylacoleo reconstructed by Owen, 1877
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 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.[8][9] Some early species of Thylacoleonidae likeLekaneleo 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.[10] Species of Wakaleo and Thylacoleo are thought to have been hypercarnivores that fed on larger prey.[10][11]
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,[12] though other authors have placed them at the base of Diprotodontia, outside of either Vombatiformes, Phalangeriformes or Macropodiformes.[13] 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:[14]
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