Torosteus

Torosteus Temporal range: Late Devonian: Frasnian, 382.7–372.2  Ma PreꞒ Ꞓ O S D C P T J K Pg N
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 pulchellusGardiner & Miles, 1990 Torosteus tuberculatusGardiner & 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. ^[1]

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

Coccosteomorphi Coccosteoidea Coccosteidae Millerosteus minor Coccosteus cuspidatus Dickosteus threiplandi Watsonosteus fletti Protitanichthys rockportensis Panxiosteidae Plourdosteus canadensis Panxiosteus ocullus Janiosteus timanicus Incisoscutoidea Harrytoombsia elegans Torosteus tuberculatus Torosteus pulchellus Mcnamaraspis kaprios Compagopiscis croucheri Trematosteus fontanellus Camuropiscidae Incisoscutum ritchiei Incisoscutum sarahae Rolfosteus canningensis Tubonasus lennardensis Fallacosteus turneri Camuropiscis laidlawi Latocamurus coulthardi Pachyosteomorphi

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 .