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Australosomus; Temporal range: Early Triassic PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	†Pholidopleuriformes
Family:	†Pholidopleuridae
Genus:	†Australosomus; Pivetau, 1930
Type species
	†Pristisomus merlei; Priem, 1924
Species
	See text

Australosomus (meaning "southern body") is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic epoch in what is now Greenland, Kenya, Tanzania, Madagascar, South Africa and Canada (British Columbia).^[3]^[4]^[1]

The type species, Australosomus merlei from Madagascar, was first described as Pristisomus merlei by Ferdinand Priem. A new genus, Australosomus, was later erected for this species by Jean Piveteau.^[5]

Australosomus is one of many genera to arise after the Permian-Triassic extinction event, only to die out during the Early Triassic,^[4] possibly during a subsequent extinction event.^[3]

Most species were marine, except for the African species, which were found in freshwater deposits.

The genus name Australosomus ("southern body") is inaccurate, as Australosomus is known as far north as Canada and Greenland, although the first known remains were described from Madagascar.

Taxonomy

Australosomus contains the following species:^[6]

†A. altisquamosus Beltan, 1980 - Late Induan of Madagascar (Sakamena Group)
†A. kochi Stensiö, 1932 - Early Induan (and possibly latest Permian) of Greenland (Wordie Creek Formation) (=A. simplex Nielsen, 1949)
†A. longirostris Beltan 1968 - Late Induan of Madagascar (Sakamena Group)
† A. merlei (Priem, 1924) - Late Induan of Madagascar (Sakamena Group)
†A. pholidopleuroides Nielsen, 1949 - Early Induan of Greenland (Wordie Creek Formation)
†A. stockleyi Haughton, 1936 - Induan of Tanzania (Karoo Supergroup)^[7]

Indeterminate remains are known from the Sulphur Mountain Formation of British Columbia and Alberta (Canada).^[8] The remains of a potentially associated genus are known from the Late Triassic Chinle Formation of Arizona.^[6] Potential remains are known from the Permian-Triassic boundary of Kenya.^[9]

Appearance

Australosomus was an elongate fish. The interlocking scales (3 to 4 times long as wide), deeply forked caudal fin all help to distinguish this genus.^[10] It achieved standard lengths of about 100 mm (3.9 in) to 310 mm (12 in).^[4]

References

^ ^a ^b Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: 560. Archived from the original on 2011-07-23. Retrieved 2009-02-27.
^ "Part 7- Vertebrates". Collection of genus-group names in a systematic arrangement. Archived from the original on 2016-10-05. Retrieved 30 June 2016.
^ ^a ^b Ludvigsen, Rolf & Beard, Graham. 1997. West Coast Fossils: A Guide to the Ancient Life of Vancouver Island. pg. 78-79
^ ^a ^b ^c Romano, Carlo; Koot, Martha B.; Kogan, Ilja; Brayard, Arnaud; Minikh, Alla V.; Brinkmann, Winand; Bucher, Hugo; Kriwet, Jürgen (2016). "Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution". Biological Reviews. 91 (1): 106–147. doi:10.1111/brv.12161. PMID 25431138. S2CID 5332637.
^ Piveteau, Jean (1930). "Particularités structurales d'un type nouveau de poisson fossile des formations permo-triasiques du nord de Madagascar". Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences (in French). 191: 456–458.
^ ^a ^b "PBDB Taxon". paleobiodb.org. Retrieved 2024-05-08.
^ Murray, A.M. (2000). "The Palaeozoic, Mesozoic and Early Cenozoic fishes of Africa". Fish and Fisheries. 1 (2): 111–145. doi:10.1046/j.1467-2979.2000.00015.x. ISSN 1467-2960.
^ Neuman, Andrew G. (2015). Therrien, François (ed.). "Fishes from the Lower Triassic portion of the Sulphur Mountain Formation in Alberta, Canada: geological context and taxonomic composition". Canadian Journal of Earth Sciences. 52 (8): 557–568. doi:10.1139/cjes-2014-0165. ISSN 0008-4077.
^ Hankel, O. (1992-05-22). "Late Permian to early triassic microfloral assemblages from the Maji ya chumvi formation, Kenya". Review of Palaeobotany and Palynology. 72 (1): 129–147. doi:10.1016/0034-6667(92)90181-F. ISSN 0034-6667.
^ Nielsen, Eigil (1949). "Studies on Triassic fishes from East Greenland 2. Australosomus and Birgeria". Palaeozoologica Groenlandica. 3: 1–309.