page_title: Tasmaniosaurus
section_title: History and Classification
hierarchical_section_title: Tasmaniosaurus / History and Classification
caption_attribution_description: Slab including the artificially assembled blocks that compose the type specimen (UTGD 54655) of Tasmaniosaurus triassicus. A, photograph; B, line drawing. Abbreviations: “il”, ilium of Camp &amp; Banks; “po”, postorbital of Camp &amp; Banks; “sf”, supratemporal fenestra of Thulborn; “sq”, squamosal of Camp &amp; Banks;&#160;?, indeterminate bone;&#160;?ep, epipterygoid;&#160;?fe, probable femur; cdv, cervico-dorsal vertebra; cv, caudal vertebrae; dr, dorsal rib; dv, dorsal vertebra; int, interclavicle; ft, foot; ga, gastralia; ha, haemal arch; la, right lacrimal; ldt, left dentary; lmx, probable left maxilla; lmxm, probable left maxilla natural mould; lsp, left splenial; pmx, right premaxilla; rdt, right dentary; rmx, probable right maxilla; rpt, right pterygoid; ti, tibia; skr, skull roof; smx, small&#160;?archosauriform maxilla. Scale bar equals 10 cm. Drawing of Fig. 2B modified from [19].
context_page_description: Tasmaniosaurus is an extinct genus of archosauromorph reptile known from the Knocklofty Formation of West Hobart, Tasmania, Australia. The type species is T. triassicus. This genus is notable not only due to being one of the most complete Australian Triassic reptiles known, but also due to being a very close relative of Archosauriformes. Once believed to be a proterosuchid, this taxon is now believed to have been intermediate between advanced non-archosauriform archosauromorphs such as Prolacerta, and basal archosauriforms such as Proterosuchus. Features traditionally used to define Archosauria and later Archosauriformes, such as the presence of an antorbital fenestra and serrated teeth, are now known to have evolved prior to those groups due to their presence in Tasmaniosaurus.
context_section_description: First named as a nomen nudum in 1974, the genus received a formal description by paleontologists Charles Lewis Camp and Maxwell Banks in 1978. These descriptions considered it a proterosuchid archosaur. A rediscription by British paleontologist Tony Thulborn in 1986 agreed with this interpretation. Since then, cladistic work has redefined the term "archosaur" to only include Avemetatarsalia (a lineage including pterosaurs and dinosaurs, such as modern birds) and Pseudosuchia (a lineage including modern crocodylians and their extinct relatives such as aetosaurs and raisuchids). As proterosuchids evolved prior to the split between these two groups, they are not considered archosaurs 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. Archosauriformes is itself a component of Archosauromorpha, a broader clade which refers to all animals more closely related to archosaurs than to lepidosaurs, the other main group of reptiles including lizards, snakes, and tuataras.
  During this transition, Tasmaniosaurus remained ignored. This was rectified when the genus received a thorough redescription by Martin Ezcurra in 2014. 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 proterosuchid. 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).
caption: Blocks of the type specimen
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