Tasmaniosaurus: Difference between revisions
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'''''Tasmaniosaurus''''' ('Lizard from Tasmania') is an [[Extinction|extinct]] [[genus]] of [[Archosauromorpha|archosauromorph]] reptile known from the [[Knocklofty Formation]] ([[Early Triassic]]) of [[West Hobart]], [[Tasmania]], [[Australia]]. The [[type species]] is ''T. triassicus''. |
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'''''Tasmaniosaurus''''' ('Lizard from Tasmania')<ref name=CB78>{{cite journal |last=Camp |first=C. L. |author2=Banks, M. R. |year=1978 |title=A proterosuchian reptile from the Early Triassic of Tasmania |journal=Alcheringa |volume=2 |pages=143–158 |doi=10.1080/03115517808619085}}</ref> is an [[archosaur]] of the family [[Proterosuchidae]], known from the [[Knocklofty Formation]] ([[Early Triassic]]) of [[West Hobart]], [[Tasmania]], [[Australia]]. It is Australia's most complete Triassic reptile fossil; the entire skeleton has been preserved. The [[type species]] is ''T. triassicus''. The genus was first described in 1978, but was first named as a ''[[nomen nudum]]'' in 1974.<ref name=TRA86>{{cite journal |last=Thulborn |first=R. A. |year=1986 |title=The Australian Triassic reptile ''Tasmaniosaurus triassicus'' (Thecodontia: Proterosuchia) |journal=Journal of Vertebrate Paleontology |volume=6 |issue=2 |pages=123–142 |doi=10.1080/02724634.1986.10011606}}</ref><ref name=CJW74>{{cite journal |last=Cosgriff |first=J. W. |year=1974 |title=Lower Triassic Temnospondyli of Tasmania |journal=Special Papers of the Geological Society of America |volume=149 |pages=1–134 |doi=10.1130/spe149-p1}}</ref> |
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== History and Classification == |
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The genus was first described in 1978 , but was first named as a ''[[nomen nudum]]'' in 1974.<ref name="CB78">{{cite journal |last=Camp |first=C. L. |author2=Banks, M. R. |year=1978 |title=A proterosuchian reptile from the Early Triassic of Tasmania |journal=Alcheringa |volume=2 |pages=143–158 |doi=10.1080/03115517808619085}}</ref><ref name="CJW74">{{cite journal |last=Cosgriff |first=J. W. |year=1974 |title=Lower Triassic Temnospondyli of Tasmania |journal=Special Papers of the Geological Society of America |volume=149 |pages=1–134 |doi=10.1130/spe149-p1}}</ref>These descriptions considered it a [[Proterosuchidae|proterosuchid]] [[archosaur]]. A rediscription by Thulborn in 1986 agreed with this interpretation.<ref name="TRA86">{{cite journal |last=Thulborn |first=R. A. |year=1986 |title=The Australian Triassic reptile ''Tasmaniosaurus triassicus'' (Thecodontia: Proterosuchia) |journal=Journal of Vertebrate Paleontology |volume=6 |issue=2 |pages=123–142 |doi=10.1080/02724634.1986.10011606}}</ref> Since then, [[Cladistics|cladistic]] work has redefined the term "[[archosaur]]" to only include bird-line archosaurs ([[Avemetatarsalia]]) and crocodile-line archosaurs ([[Pseudosuchia]]). As proterosuchids evolved prior to the split between these two groups, they are not considered archosurs using this definition. In lieu of this revelation, the clade [[Archosauriformes]] is now used to encompass proterosuchids and archosaurs (as well as several other [[Family (biology)|families]]) under one group. |
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During this transition, ''Tasmaniosaurus'' remained ignored. This was rectified when the genus received a thorough redescription by Ezcurra in 2014.<ref>{{Cite journal|last=Ezcurra|first=Martín D.|date=2014-01-30|title=The Osteology of the Basal Archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia|url=http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0086864|journal=PLOS ONE|language=en|volume=9|issue=1|pages=e86864|doi=10.1371/journal.pone.0086864|issn=1932-6203}}</ref> In 2016, Ezcurra also included the genus in his comprehensive analysis of Archosauromorphs, which indicated that proterosuchidae (as it was usually defined) was an invalid [[Polyphyly|polyphyletic]] grouping. This analysis included a phylogenetic analysis which incorporated ''Tasmaniosaurus'' and found that it was not in fact a proterosuchidae. Rather, it was found to be the sister taxon of Archosauriformes, meaning that it was the closest known relative of members of that clade without technically being part of it (as it was not closer to either proterosuchids or other archosauriforms).<ref name=":0">{{Cite journal|last=Ezcurra|first=Martín D.|date=2016-04-28|title=The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms|url=https://peerj.com/articles/1778/|journal=PeerJ|language=en|volume=4|doi=10.7717/peerj.1778|issn=2167-8359}}</ref> |
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== Description == |
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[[File:Tasmaniosaurus triassicus.png|thumb|left|Blocks of the type specimen]] |
[[File:Tasmaniosaurus triassicus.png|thumb|left|Blocks of the type specimen]] |
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''Tasmaniosaurus'' is known from a single partial skeleton, UTGD ([[University of Tasmania]] School of Earth Sciences) 54655. This holotype specimen consists of various skull fragments, vertebrae, ribs, and limb bones. It is considered one of the most complete skeletons of any Triassic reptile unearthed in Australia. A few other bone fragments collected around Tasmania have been occasionally referred to this genus, but they are currently considered indeterminate and lost.<ref name=":0" /> |
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| ⚫ | ''Tasmaniosaurus'' was about 1 metre long, and similar in appearance to the [[proterosuchid]] ''[[Chasmatosaurus]]'' from Africa and China, which may be its closest relative.<ref name=TRA79>{{cite journal |last=Thulborn |first=R. A. |year=1979 |title=A proterosuchian thecodont from the Rewan Formation of Queensland |journal=Memoirs of the Queensland Museum |volume=19 |pages=331–355}}</ref> It is however distinguished from other proterosuchids by the presence of an interclavicle, which other members had lost. The premaxilla is slightly curved. The teeth are sharp. It may have fed, amongst other creatures, on [[labyrinthodonts]], as remains of these amphibians are associated with the skeleton. It is surmised that many proterosuchids lived an amphibious, predatory life like crocodiles today. ''Tasmaniosaurus'' had no dermal [[scutes]]. |
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''Tasmaniosaurus'' is one of the earliest reptiles known to have lived in Australia. Another proterosuchid, ''[[Kalisuchus]] rewanensis'', is known from the Early Triassic of Queensland, Australia. |
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| ⚫ | ''Tasmaniosaurus'' was about 1 metre long, and similar in appearance to the [[proterosuchid]] ''[[Chasmatosaurus]]'' from Africa and China, which may be its closest relative.<ref name="TRA79">{{cite journal |last=Thulborn |first=R. A. |year=1979 |title=A proterosuchian thecodont from the Rewan Formation of Queensland |journal=Memoirs of the Queensland Museum |volume=19 |pages=331–355}}</ref> It is however distinguished from other proterosuchids by the presence of an interclavicle, which other members had lost. The premaxilla is slightly curved. The teeth are sharp. It may have fed, amongst other creatures, on [[labyrinthodonts]], as remains of these amphibians are associated with the skeleton. It is surmised that many proterosuchids lived an amphibious, predatory life like crocodiles today. ''Tasmaniosaurus'' had no dermal [[scutes]]. ''Tasmaniosaurus'' is one of the earliest reptiles known to have lived in Australia. Another proterosuchid, ''[[Kalisuchus]] rewanensis'', is known from the Early Triassic of Queensland, Australia. |
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==References== |
==References== |
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Revision as of 21:08, 23 February 2018
| Tasmaniosaurus Temporal range: Early Triassic
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| Genus: | Tasmaniosaurus Camp and Banks, 1978
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Tasmaniosaurus ('Lizard from Tasmania') is an extinct genus of archosauromorph reptile known from the Knocklofty Formation (Early Triassic) of West Hobart, Tasmania, Australia. The type species is T. triassicus.
History and Classification
The genus was first described in 1978 , but was first named as a nomen nudum in 1974.[1][2]These descriptions considered it a proterosuchid archosaur. A rediscription by Thulborn in 1986 agreed with this interpretation.[3] Since then, cladistic work has redefined the term "archosaur" to only include bird-line archosaurs (Avemetatarsalia) and crocodile-line archosaurs (Pseudosuchia). As proterosuchids evolved prior to the split between these two groups, they are not considered archosurs using this definition. In lieu of this revelation, the clade Archosauriformes is now used to encompass proterosuchids and archosaurs (as well as several other families) under one group.
During this transition, Tasmaniosaurus remained ignored. This was rectified when the genus received a thorough redescription by Ezcurra in 2014.[4] In 2016, Ezcurra also included the genus in his comprehensive analysis of Archosauromorphs, which indicated that proterosuchidae (as it was usually defined) was an invalid polyphyletic grouping. This analysis included a phylogenetic analysis which incorporated Tasmaniosaurus and found that it was not in fact a proterosuchidae. Rather, it was found to be the sister taxon of Archosauriformes, meaning that it was the closest known relative of members of that clade without technically being part of it (as it was not closer to either proterosuchids or other archosauriforms).[5]
Description
Tasmaniosaurus is known from a single partial skeleton, UTGD (University of Tasmania School of Earth Sciences) 54655. This holotype specimen consists of various skull fragments, vertebrae, ribs, and limb bones. It is considered one of the most complete skeletons of any Triassic reptile unearthed in Australia. A few other bone fragments collected around Tasmania have been occasionally referred to this genus, but they are currently considered indeterminate and lost.[5]
Tasmaniosaurus was about 1 metre long, and similar in appearance to the proterosuchid Chasmatosaurus from Africa and China, which may be its closest relative.[6] It is however distinguished from other proterosuchids by the presence of an interclavicle, which other members had lost. The premaxilla is slightly curved. The teeth are sharp. It may have fed, amongst other creatures, on labyrinthodonts, as remains of these amphibians are associated with the skeleton. It is surmised that many proterosuchids lived an amphibious, predatory life like crocodiles today. Tasmaniosaurus had no dermal scutes. Tasmaniosaurus is one of the earliest reptiles known to have lived in Australia. Another proterosuchid, Kalisuchus rewanensis, is known from the Early Triassic of Queensland, Australia.
References
- ^ Camp, C. L.; Banks, M. R. (1978). "A proterosuchian reptile from the Early Triassic of Tasmania". Alcheringa. 2: 143–158. doi:10.1080/03115517808619085.
- ^ Cosgriff, J. W. (1974). "Lower Triassic Temnospondyli of Tasmania". Special Papers of the Geological Society of America. 149: 1–134. doi:10.1130/spe149-p1.
- ^ Thulborn, R. A. (1986). "The Australian Triassic reptile Tasmaniosaurus triassicus (Thecodontia: Proterosuchia)". Journal of Vertebrate Paleontology. 6 (2): 123–142. doi:10.1080/02724634.1986.10011606.
- ^ Ezcurra, Martín D. (2014-01-30). "The Osteology of the Basal Archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia". PLOS ONE. 9 (1): e86864. doi:10.1371/journal.pone.0086864. ISSN 1932-6203.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Ezcurra, Martín D. (2016-04-28). "The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms". PeerJ. 4. doi:10.7717/peerj.1778. ISSN 2167-8359.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Thulborn, R. A. (1979). "A proterosuchian thecodont from the Rewan Formation of Queensland". Memoirs of the Queensland Museum. 19: 331–355.
Long, J.A., Dinosaurs of Australia and New Zealand, UNSW Press 1998
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