Thylacoleonidae Explained

Thylacoleonidae is a family of extinct carnivorous diprotodontian marsupials from Australia, referred to as marsupial lions.[1] The best known is Thylacoleo carnifex, also called the marsupial lion.[2] 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,[3] which functioned as the carnassial teeth.[4] 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 590g, while the last species of the family, the Pleistocene Thylacoleo carnifex is suggested to have had a body mass of around 160kg (350lb), comparable to a big cat.[5] 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.[6] [7] 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.[8]

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.[9] 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.[10] 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.[11]

Classification

Five genera are currently accepted as belonging to this family:[12]

Cladogram after Gillespie (2023):

Notes and References

  1. 10.1071/ZO9880565. Circumventing a Constraint - the Case of Thylacoleo (Marsupialia, Thylacoleonidae). Werdelin. L. Australian Journal of Zoology. 36. 565. 1988. 5.
  2. Web site: Move Over Sabre-Tooth Tiger. https://web.archive.org/web/20030310111637/http://www.austmus.gov.au/mammals/fossil/move_over_sabre.htm. dead. 2003-03-10. Wroe. Stephen. Australian Museum. 2008-06-03.
  3. Gillespie . Anna K. . Archer . Michael . Hand . Suzanne J. . 2016 . A tiny new marsupial lion (Marsupialia, Thylacoleonidae) from the early Miocene of Australia . Palaeontologia Electronica . Palaeontological Association . 19 . 2.26A . 1–26 . 10.26879/632 . free . 29 August 2016.
  4. Werdelin . L . 1988 . Circumventing a Constraint - the Case of Thylacoleo (Marsupialia, Thylacoleonidae) . Australian Journal of Zoology . en . 36 . 5 . 565 . 10.1071/ZO9880565 . 0004-959X.
  5. Gillespie . Anna K. . Archer . Michael . Hand . Suzanne J. . 2019-09-03 . Lekaneleo, a new genus of marsupial lion (Marsupialia, Thylacoleonidae) from the Oligocene–Miocene of Australia, and the craniodental morphology of L. roskellyae, comb. nov. . Journal of Vertebrate Paleontology . en . 39 . 5 . e1703722 . 10.1080/02724634.2019.1703722 . 2019JVPal..39E3722G . 0272-4634.
  6. Figueirido . Borja . Martín-Serra . Alberto . Janis . Christine M. . August 2016 . Ecomorphological determinations in the absence of living analogues: the predatory behavior of the marsupial lion (Thylacoleo carnifex) as revealed by elbow joint morphology . Paleobiology . en . 42 . 3 . 508–531 . 2016Pbio...42..508F . 10.1017/pab.2015.55 . 0094-8373 . 87168573 . 1983/1f3ac566-0b08-48fb-b27c-63fe4256c138. free .
  7. Warburton . Natalie M. . Yates . Adam. M. . 2020-12-10 . Functional morphology of Wakaleo postcrania from the middle to late Miocene of central Australia reveals new insights in the evolution of marsupial hypercarnivores . Journal of Vertebrate Paleontology . en . 40 . 6 . e1878203 . 10.1080/02724634.2021.1878203 . 2020JVPal..40E8203W . 0272-4634.
  8. Yates . Adam M. . 2015-11-12 . New craniodental remains of Wakaleo alcootaensis (Diprotodontia: Thylacoleonidae) a carnivorous marsupial from the late Miocene Alcoota Local Fauna of the Northern Territory, Australia . PeerJ . en . 3 . e1408 . 10.7717/peerj.1408 . free . 26587359 . 4647553 . 2167-8359.
  9. Beck . Robin M.D. . Voss . Robert S. . Jansa . Sharon A. . 2022-06-28 . Craniodental Morphology and Phylogeny of Marsupials . Bulletin of the American Museum of Natural History . 457 . 1 . 10.1206/0003-0090.457.1.1 . 0003-0090.
  10. Gill . Theodore . Theodore Gill . Arrangement of the families of mammals. With analytical tables. Prepared for the Smithsonian institution. . Smithsonian Miscellaneous Collections . 1872 . 11 . 1–98 . Smithsonian Institution.
  11. 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 . 10.1080/14772019.2017.1391885 . 90758394 . Anna K. Gillespie . Mike Archer (paleontologist) . S. J. Hand.
  12. Web site: Haaramo. Mikko. Diprotodontia - diprotodonts. Mikko's Phylogeny Archive. 2007-12-29.
  13. Gillespie . A. K. . Two new marsupial lion taxa (Marsupialia, Thylacoleonidae) from the early and Middle Miocene of Australia . Alcheringa: An Australasian Journal of Palaeontology . 2023 . 47 . 4 . 506–521 . 10.1080/03115518.2022.2152096. 2023Alch...47..506G . 256157821 .
  14. News: Gough. Myles. Kitten-sized extinct 'lion' named after David Attenborough. BBC News . 25 August 2016 . 29 August 2016.

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