Muribacinus is an extinct genus of thylacinid that lived during the middle Miocene in what is now northwestern Queensland, Australia. It was described in 1995 from remains collected at the Riversleigh World Heritage Area. Only one species is known, M. gadiyuli.
| Muribacinus Temporal range: middle Miocene,
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| Holotype and paratype specimens of Muribacinus. | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Dasyuromorphia |
| Family: | †Thylacinidae |
| Genus: | †Muribacinus |
| Species: | †M. gadiyuli
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| Binomial name | |
| †Muribacinus gadiyuli Wroe, 1995
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History and naming
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Muribacinus was named in 1995 by Stephen Wroe based on fossils recovered from the Riversleigh World Heritage Area, northwestern Queensland. The holotype, QMF 30836, is a partial right maxilla and jugal collected from the Gag site. A right dentary from Henk’s Hollow site was assigned to the genus based on the proportions of the molar's shearing crests.[1]
The generic name is a combination of the Waanyi word "muriba" (father) and the Ancient Greek stem word "-kynos" (dog), for the assumed classification as an early thylacinid species. The specific name comes from the Waanyi word “gadiyuli” (little).[1]
Description
editAlthough smaller than most thylacinids, Muribacinus would have been similar in size to the modern Tiger quoll. Wroe (2001) estimated its weight to have been 1.6 kg (3.5 lbs), while Rovinsky et al. (2019) gave it a slightly larger estimate of 1.6–1.7 kg (3.5-3.7 lbs).[2][3]
The teeth of Muribacinus retain large protocone cusps and talonids. The paracone and metacone cusps have a large distance between them. On each molar, the metaconid cusps and the small shelf that runs along the labial side of the tooth (called the stylar shelf) aren't as small as in other thylacinids. The second premolar is larger than the third premolar. The crest in front of the paracone (known as the preparacrista) is longer relative to the lingual border of the metacone (postmetacrista) on the second and third molars.[1]
Classification
editThe first phylogenetic analysis that included Muribacinus found it to be in a polytomy with Mutpuracinus, Nimbacinus and clade containing all other thylacinids.[4] Subsequent studies throughout the years have, however, recovered conflicting results. Both Murray & Megirian (2000) and Yates (2015) have recovered as the basalmost member of Thylacinidae.[5][6] In at least two phylogenetic analyses performed by Rovinsky et al. (2019), Muribacinus formed a minor clade with the early-middle Miocene taxa Ngamalacinus and Nimbacinus as a sister group to all other thylacinids.[3]
In at least one phylogenetic analysis performed by Churchill et al. (2024), Muribacinus was found to be a non-thylacinid dasyuromorphian, specifically within a polytomy with a well supported clade containing Barinya, Tyarrpecinus, Myrmecobius and Dasyuridae.[7]
Paleobiology
editAlthough not directly dated, both the Gag site and Henk’s Hollow site are thought to have been middle Miocene in age, with a date range of ~15.1 to 12.9 Ma.[3] During this time, Australia's climate would have been relatively warmer and wetter than it is today.[8] The terrestrial biome of Riversleigh at the time has been interpreted as either being open forest or rainforest.[9]
Contemporaneous with Muribacinus was the medium-sized, hypercarnivorous thylacinid Wabulacinus macknessi, and the small to medium-sized thylacoleonids Wakaleo oldfieldi and Lekaneleo myersi.[10][11] Differences in body size and vertical segregation have been suggested to have reduced competition between the two families.[12] As a result of its pronounced metaconid cusps, Muribacinus is thought to have been an unspecialised faunivore that fed on small vertebrates and invertebrates.[3]
References
edit- ^ a b c Wroe, Stephen (1995). "Muribacinus gadiyuli (Thylacinidae: Marsupialia), a very plesiomorphic thylacinid from the Miocene of Riversleigh, northwestern Queensland, and the problem of paraphyly for the Dasyuridae (Marsupialia)". Journal of Paleontology. 70 (6): 1032–1044. doi:10.1017/S0022336000038737. S2CID 131861751.
- ^ Wroe, S. (2001). "Maximucinus muirheadae, gen. et sp. nov. (Thylacinidae : Marsupialia), from the Miocene of Riversleigh, north-western Queensland, with estimates of body weights for fossil thylacinids". Australian Journal of Zoology. 49 (6): 603–314. doi:10.1071/ZO01044.
- ^ a b c d Rovinsky, Douglass S.; Evans, Alistair R.; Adams, Justin W. (2019-09-02). "The pre-Pleistocene fossil thylacinids (Dasyuromorphia: Thylacinidae) and the evolutionary context of the modern thylacine". PeerJ. 7: e7457. doi:10.7717/peerj.7457. ISSN 2167-8359. PMC 6727838.
- ^ B. Wroe S. 2003. "Australian marsupial carnivores: recent advances in palaeontology." In: Jones M, Dickman C, Archer M, eds. Predators with Pouches: The Biology of Carnivorous marsupials. Collingwood: CSIRO Publishing. 102-123
- ^ Murray, P.; Megirian, D. (2000). "Two New Genera and Three New Species of Thylacinidae (Marsupialia) from the Miocene of the Northern Territory, Australia". The Beagle: Occasional Papers of the Northern Territory Museum of Arts and Sciences. 16: 145–162.
- ^ Yates, A.M. (12 May 2015). "Thylacinus (Marsupialia: Thylacinidae) from the Mio-Pliocene boundary and the diversity of Late Neogene thylacinids in Australia". PeerJ. 3: e931. doi:10.7717/peerj.931. PMC 4435473. PMID 26019996.
- ^ Churchill, T. J.; Archer, M.; Hand, S. J. (2024). "Three new thylacinids (Marsupialia, Thylacinidae) from late Oligocene deposits of the Riversleigh World Heritage Area, northwestern Queensland". Journal of Vertebrate Paleontology. doi:10.1080/02724634.2024.2384595.
- ^ Woodhead, J.; Hand, S.J.; Archer, M.; Graham, I.; Sniderman, K.; Arena, D.A.; Black, K.H.; Godthelp, H.; Creaser, P.; Price, E. (2014). "Developing a radiometrically-dated chronologic sequence for Neogene biotic change in Australia, from the Riversleigh World Heritage Area of Queensland". Gondwana Research. 29 (1): 153–167. doi:10.1016/j.gr.2014.10.004.
- ^ Travouillon, K.J.; Legendre, S.; Archer, M.; Hand, S.J. (2009). "Palaeoecological analyses of Riversleigh's Oligo-Miocene sites: implications for Oligo-Miocene climate change in Australia". Palaeogeography, Palaeoclimatology, Palaeoecology. 38 (4): 24–37. doi:10.1016/j.palaeo.2009.02.025.
- ^ Muirhead, J.; Gillespie, A.K. (1995). "Additional Parts of The Type Specimen of Thylacinus macknessi (Marsupialia: Thylacinidae) From Miocene Deposits of Riversleigh, Northwestern Queensland" (PDF). Australian Mammalogy. 18 (1): 55–60.
- ^ Gillespie, A. K.; Archer, M.; Hand, S.J.; Black, K. H. (2014). "New material referable to Wakaleo (Marsupialia: Thylacoleonidae) from the Riversleigh World Heritage Area, northwestern Queensland: revising species boundaries and distributions in Oligo/ Miocene marsupial lions". Alcheringa: An Australasian Journal of Palaeontology. 38 (4): 513–527. doi:10.1080/03115518.2014.908268.
- ^ Gillespie, A. K. (2023). "Two new marsupial lion taxa (Marsupialia, Thylacoleonidae) from the early and Middle Miocene of Australia". Alcheringa: An Australasian Journal of Palaeontology. 47 (4): 506–521. Bibcode:2023Alch...47..506G. doi:10.1080/03115518.2022.2152096. S2CID 256157821.