Torosteus

{{Automatic_taxobox

| fossil_range = Late Devonian: Frasnian, {{Fossil range|382.7|372.2}}

| display_parents = 4

| taxon = Torosteus

| authority = Gardiner & Miles, 1990

| subdivision_ranks = Species

| subdivision =

Torosteus pulchellus Gardiner & Miles, 1990
Torosteus tuberculatus Gardiner & Miles, 1990

}}

Torosteus is an extinct genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period. Fossils are found in the Kimberley region of Australia.{{Cite journal |last1=Zhu |first1=You-An |last2=Zhu |first2=Min |last3=Wang |first3=Jun-Qing |date=1 April 2016 |title=Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci |journal=Zoological Journal of the Linnean Society |volume=176 |issue=4 |pages=806–834 |doi=10.1111/zoj.12356|issn=0024-4082 |doi-access=free }}

Description

Torosteus's body size and morphology are similar to Incisoscutum and Compagopiscis, suggesting a possible pelagic lifestyle, although they were on different trophic levels of their ecosystem.{{Cite journal |last1=Trinajstic |first1=Kate |last2=Briggs |first2=Derek E. G. |last3=Long |first3=John A. |date=23 November 2021 |title=The Gogo Formation Lagerstätte: a view of Australia's first great barrier reef |journal=Journal of the Geological Society |volume=179 |issue=1 |issn=0016-7649 |doi=10.1144/jgs2021-105 |doi-access=free }} Bite force analysis has suggested that it was an active predator, and fossils have been found in numbers, suggesting possible schooling behavior.

Phylogeny

Torosteus was originally classified as a member of the family Plourdosteidae.{{Cite journal |last1=Carr |first1=R.K. |last2=Hlavin |first2=W.J. |title=Two new species of Dunkleosteus Lehman, 1956, from the Ohio Shale Formation (USA, Famennian) and the Kettle Point Formation (Canada, Upper Devonian), and a cladistic analysis of the Eubrachythoraci (Placodermi, Arthrodira) |journal=Zoological Journal of the Linnean Society |volume=159 |issue=1 |pages=195-222 |year=2010 |doi=10.1111/j.1096-3642.2009.00578.x |doi-access=free }} However, phylogenetic analysis later found Plourdosteidae to be an invalid grouping, and the family was dismissed.{{Cite journal |author1=You-An Zhu |author2=Min Zhu |title=A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci | journal=Zoological Journal of the Linnean Society |volume=169 |issue=4 |pages=798-819 |year=2013 |doi=10.1111/zoj12089 |doi-access=free }} Torosteus is now considered to be a member of the superfamily Incisoscutoidea, which belongs to the clade Coccosteomorphi, one of the two major clades within Eubrachythoraci. The cladogram below shows the phylogeny of Torosteus: