Torosteus

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.[1]

Torosteus
Temporal range: Late Devonian: Frasnian,
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: †Placodermi
Order: †Arthrodira
Suborder: †Brachythoraci
Clade: †Eubrachythoraci
Clade: †Coccosteomorphi
Superfamily: †Incisoscutoidea
Genus: †Torosteus
Gardiner & Miles, 1990
Species
  • Torosteus pulchellus Gardiner & Miles, 1990
  • Torosteus tuberculatus Gardiner & Miles, 1990

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.[2] Bite force analysis has suggested that it was an active predator, and fossils have been found in numbers, suggesting possible schooling behavior.[2]

Phylogeny

Torosteus was originally classified as a member of the family Plourdosteidae.[3] However, phylogenetic analysis later found Plourdosteidae to be an invalid grouping, and the family was dismissed.[4] 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:[1]

Eubrachythoraci 

References
  1. Zhu, You-An; Zhu, Min; Wang, Jun-Qing (1 April 2016). "Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci". Zoological Journal of the Linnean Society. 176 (4): 806–834. doi:10.1111/zoj.12356. ISSN 0024-4082.
  2. Trinajstic, Kate; Briggs, Derek E. G.; Long, John A. (23 November 2021). "The Gogo Formation Lagerstätte: a view of Australia's first great barrier reef". Journal of the Geological Society. 179 (1). doi:10.1144/jgs2021-105. ISSN 0016-7649.
  3. Carr, R.K.; Hlavin, W.J. (2010). "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)". Zoological Journal of the Linnean Society. 159 (1): 195–222. doi:10.1111/j.1096-3642.2009.00578.x.
  4. You-An Zhu; Min Zhu (2013). "A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci". Zoological Journal of the Linnean Society. 169 (4): 798–819. doi:10.1111/zoj12089.


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