Torosteus
Temporal range: Late Devonian: Frasnian,
Scientific classification Edit this 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

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. 1 2 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. 1 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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