Thylacoleonidae

Thylacoleonidae is a family of extinct meat-eating 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 Pleistocene, with some species the size of a possum and others as large as a leopard. As a whole, they were largely arboreal, in contrast to the mostly terrestrial dasyuromorphs (quolls only recently took the niches vacated by small thylacoleonids), monitor lizards and mekosuchines.[4]

Thylacoleonidae
Temporal range: Late Oligocene–Pleistocene
Thylacoleo
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Suborder: Vombatiformes
Family: †Thylacoleonidae
Gill, 1872[1]
Genera

Hypercarnivory was also found in another order of marsupials, the dasyuromorph family Thylacinidae that included the Tasmanian tiger Thylacinus cynocephalus that became extinct in the twentieth century.

Description
Illustration of lower dentition reconstructed by Owen, 1877

A diprotodontian family allied to the Vombatiformes, mammals that radiated and diversified in the Oligocene to Miocene. The thylacoleonid genera exhibit specialised dentition that allowed them to kill prey larger than themselves.

The earliest descriptions of the most recent species recognise the secateur-like blades of the teeth as a powerful mammalian predator, a "marsupial lion," that were noted as missing in the Australian environment. The third premolars exhibit this blade-like development, becoming greatly enlarged in the Pleistocene species Thylacoleo carnifex, prompting the description by Owen as "…one of the fellest and most destructive of predatory beasts."[5] They are seen as presumably occupying a trophic level as peak predators in their local ecologies, some smaller and arboreal climbers while those terrestrial species are sizably comparable to large dog or a big cat.

Distribution and habitat

The genera are associated with the late Oligocene and Miocene epochs. Microleo and Wakaleo have been located at the Lake Pitikanta fossil area in Central Australia and toward the northern coast at Riversleigh, below the gulf of Carpentaria, a rich source of fossil fauna. The most recent species, Thylacoleo carnifex, existed at least until the Pleistocene, the earliest known specimens of the family are dated to around twenty five million years ago.[6]

Taxonomy

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).

They are now thought to be allied with the Vombatiformes, still represented in the modern Australian fauna by koalas and wombats. They appear to have diverged by specialising in a carnivorous diet in the early Oligocene, and increased in size along with their prey during the Miocene.

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.[5]

Classification

Four genera are currently accepted as belonging to this family:[7]

  • Incertae sedis

References
  1. Gill, Theodore (1872). "Arrangement of the families of mammals. With analytical tables. Prepared for the Smithsonian institution". Smithsonian Miscellaneous Collections. Smithsonian Institution. 11: 1–98.
  2. Werdelin, L (1988). "Circumventing a Constraint - the Case of Thylacoleo (Marsupialia, Thylacoleonidae)". Australian Journal of Zoology. 36 (5): 565. doi:10.1071/ZO9880565.
  3. Wroe, Stephen. "Move Over Sabre-Tooth Tiger". Australian Museum. Archived from the original on 2003-03-10. Retrieved 2008-06-03.
  4. Gillespie, Anna K.; Archer, Michael; Hand, Suzanne J. (2016). "A tiny new marsupial lion (Marsupialia, Thylacoleonidae) from the early Miocene of Australia" (PDF). Palaeontologia Electronica. Palaeontological Association. 19 (2.26A): 1–26. doi:10.26879/632. Retrieved 29 August 2016.
  5. Gillespie, A.K.; Archer, M.; Hand, S.J. (6 December 2017). "A new Oligo–Miocene marsupial lion from Australia and revision of the family Thylacoleonidae". Journal of Systematic Palaeontology. 17 (1): 59–89. doi:10.1080/14772019.2017.1391885. S2CID 90758394.
  6. Gillespie, A. (7 December 2017). "A new species of marsupial lion tells us about Australia's past". The Conversation.
  7. Haaramo, Mikko. "Diprotodontia - diprotodonts". Mikko's Phylogeny Archive. Retrieved 2007-12-29.
  8. Gough, Myles. "Kitten-sized extinct 'lion' named after David Attenborough". BBC News. British Broadcasting Corporation. Retrieved 29 August 2016.


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