Microsteus

Microsteus; Temporal range: Late Frasnian[1]
	Reconstruction of M. dubius
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Placodermi
Order:	Arthrodira
Suborder:	Brachythoraci
Infraorder:	Coccosteina
Superfamily:	Dinichthyloidea
Family:	Selenosteidae
Genus:	Microsteus
Type species
	Microsteus dubius; Gross 1932
Species
	M. dubius Gross 1932; M. angusticeps (Stensiö 1963); M. gracilis (Stensiö 1963);
Synonyms
	Parawalterosteus angusticeps Stensiö 1963; Parawalterosteus gracilis Stensiö 1963;

Microsteus is a genus of small selenosteid arthrodire placoderms known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Germany.[1]^:96

There are three species, M. dubius (the type species), M. angusticeps, and M. gracilis. M. angusticeps differs from the type species in having a head with an angular profile, and M. gracilis differs from the other two species by being somewhat narrower in cross-section. Denison (1978) suggests that M. angusticeps and M. gracilis do not have enough differences from M. dubius to merit separate species status, but other authors, such as Rücklin 2011, treat the three as separate species.[2]

M. angusticeps and M. gracilis originally composed the genus Parawalterosteus. However, Denison (1978) points out that the two species are not distinct from Microsteus, and synonymized Parawalterosteus with the former genus.

References

Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 98. ISBN 9780895740274.
RÜCKLIN, MARTIN (January 14, 2011). "First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical implications". Palaeontology. 56 (1): 25–62. doi:10.1111/j.1475-4983.2010.01026.x.

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[Denison-1] Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 98. ISBN 9780895740274.

[RM11-2] RÜCKLIN, MARTIN (January 14, 2011). "First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical implications". Palaeontology. 56 (1): 25–62. doi:10.1111/j.1475-4983.2010.01026.x.