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Temporal range: Middle to Late Frasnian[1]
Synauchenia coalescens.jpg
S. coalescens
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Placodermi
Order: Arthrodira
Suborder: Brachythoraci
Infraorder: Coccosteina
Superfamily: Brachydeiroidea
Family: Brachydeiridae
Gross, 1932
Genus: Synauchenia
Jaekel, 1919
Binomial name
Synauchenia coalescens
Gross, 1932
  • Synosteus Jaekel, 1926

Synauchenia coalescens is a trout-sized, highly compressed arthrodire placoderm restricted to the Late Frasnian-aged Kellwasserkalk Fauna of Bad Wildungen.[1]

S. coalescens is unique among arthrodires in that the head shield and the trunk shield are fused or "firmly sutured" together in an immobile, helmet-like unit.[1] The neck gap is absent, and the articulations between the cranium and thorax are lost in the evolution of this peculiar feature.[1] The skull of the holotype is 10 cm long.

S. coalescens was originally placed in its own family, but, it was later determined to be closely related to Oxyosteus and Brachydeirus, and accordingly placed within Brachydeiridae.

See also[edit]


  1. ^ a b c d Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 74. ISBN 9780895740274.