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Watsonosteus Temporal range: Middle Devonian: Late Givetian, 387.7–382.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Watsonosteus fossil specimen
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Placodermi
Order:	†Arthrodira
Suborder:	†Brachythoraci
Family:	†Coccosteidae
Genus:	†Watsonosteus Miles & Westoll, 1963
Species
Watsonosteus fletti (Watson, 1932) (type)
Synonyms
Coccosteus fletti Watson, 1932

Watsonosteus is an extinct genus of coccosteid arthrodire placoderm from the Late Givetian stage of the Middle Devonian period. Fossils are found in the Orkney Islands, Scotland. It was a small placoderm with a total body length of 57 cm (22 in), with the largest individuals reaching lengths of 1 m (39 in). It is one of the few arthrodires for which complete body fossils are known.

Phylogeny

Watsonosteus is a member of the family Coccosteidae, which belongs to the clade Coccosteomorphi, one of the two major clades within Eubrachythoraci. The cladogram below shows the phylogeny of Watsonosteus:

References

1. Engelman, Russell K. (2023). "A Devonian Fish Tale: A New Method of Body Length Estimation Suggests Much Smaller Sizes for Dunkleosteus terrelli (Placodermi: Arthrodira)". Diversity. 15 (3). 318. doi:10.3390/d15030318.
2. Newman, Michael J.; Blaauwen, Jan; Burrow, Carole; Jones, Roger (January 2021). "Earliest vertebrate embryos in the fossil record (Middle Devonian, Givetian)". Palaeontology. 64 (1): 21–30. Bibcode:2021Palgy..64...21N. doi:10.1111/pala.12511. S2CID 225001446.
3. 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.

v t e Arthrodira
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Infraphylum: Gnathostomata Class: "Placodermi" Gnathostomata see Gnathostomata Placodermi see Placodermi Arthrodira see below↓
Arthrodira Arthrodira Aethaspis Aleosteus Anarthraspis Antarctaspis Baringaspis Bryantolepis Erikaspis Eskimaspis Heightingtonaspis Kujdanowiaspis Lataspis Lehmanosteus Mediaspis Proaethaspis Qataraspis Sigaspis Simblaspis Yujiangolepis Wuttagoonaspidae Wuttagoonaspis Yiminaspis Phyllolepida Gavinaspis Phyllolepididae Austrophyllolepis Cobandrahlepis Cowralepis Phyllolepis Placolepis Yurammia Actinolepidae Actinolepis Ailuracantha Bollandaspis Szelepis Phlyctaenioidei Dicksonosteus Phlyctaeniidae Aggeraspis Arctaspis Barwickosteus Cartieraspis Diadsomaspis Elegantaspis Gaspeaspis Grifftaylor Heterogaspis Huginaspis Kolpaspis Kueichowlepis Lyhoalepis Neophlyctaenius Pageauaspis Phlyctaenius Prosphymaspis Stipatosteus Arctolepididae Arctolepis Heintzosteus Huginaspis? Kueichowlepis? Groenlandaspididae Africanaspis Boomeraspis Cosmacanthus Groenlandaspis Mithakaspis Mulgaspis Tiaraspis Turrisaspis Williamsaspididae Elvaspis Williamsaspis Brachythoraci Antineosteus Dhanguura? Gemuendenaspis Maideria Xiangshuiosteus? Holonematidae Artesonema Belemnacanthus Bimbianga Deirosteus Deveonema Gyroplacosteus Holonema Megaloplax Rhenonema Tropidosteus Tropinema Homostiidae Angarichthys Cathlesichthys Dhanguura? Euleptaspis Euleptaspis Luetkeichthys Migmatocephala Antineosteus Atlantidosteus Homosteus Tityosteus Buchanosteidae Arenipiscis Buchanosteus Burrinjucosteus Errolosteus Exutaspis Goodradigbeeon Narrominaspis Parabuchanosteus Toombsosteus Taemasosteus Uralosteus Eubrachythoraci see below↓
Eubrachythoraci Coccosteomorphi Coccosteoidea Coccosteidae Belgiosteus Clarkeosteus Coccosteus Dickosteus Jiuchengia Livosteus Millerosteus Protitanichthys Watsonosteus Panxiosteidae Janiosteus Kimberleyichthys? Panxiosteus Plourdosteus? Incisoscutoidea Belosteus? Compagopiscis Cyrtosteus? Harrytoombsia? Mcnamaraspis? Parabelosteus? Torosteus Trematosteus Camuropiscidae Camuropiscis Fallacosteus Incisoscutum Latocamurus Rolfosteus Tubonasus Pachyosteomorphi Leptosteus Rhachiosteus Dunkleosteoidea Dunkleosteus Eastmanosteus Golshanichthys Hussakofia Kiangyousteus Westralichthys Xiangshuiosteus? Heterosteidae Herasmius Heterosteus Yinostius Aspinothoracidi Bruntonichthys Bullerichthys Bungartius Dinichthys Dinomylostoma Erromenosteus Hadrosteus Holdenius Kendrickichthys Mylostoma Squamatognathus Tafilalichthys Tapinosteus Titanichthys Brachydeiridae Brachydeirus Oxyosteus Synauchenia Selenosteidae Alienacanthus Amazichthys Brachyosteus Braunosteus Draconichthys Enseosteus Gorgonichthys Gymnotrachelus Heintzichthys Melanosteus Microsteus Pachyosteus Paramylostoma Phymosteus Rhinosteus Selenosteus Stenosteus Walterosteus

• Coccosteidae
• Givetian life
• Fossils of Scotland
• Animals described in 1932