Brachydeiridae

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Brachydeiridae
Temporal range: Middle to Late Frasnian
Brachydeirus grandis.jpg
Restoration of B. grandis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Placodermi
Order: Arthrodira
Suborder: Brachythoraci
Superfamily: Brachydeiroidea
Family: Brachydeiridae
Gross, 1932
Type species
Brachydeirus carinatus
Gross, 1932
Genera
Synonyms
  • Brachydiridae Gross, 1932
  • Synaucheniidae Gross, 1932
  • Auchenosteidae Jaekel, 1911
  • Oxyosteidae Gross, 1932

Brachydeiridae is a family of small to moderately large-sized arthrodire placoderms from the Late Devonian of Europe, restricted primarily to the Kellwasserkalk Fauna of Bad Wildungen and Adorf.

Contents

Brachydeirids have, in cross section, a highly compressed body, a pointed, sometimes highly elongated snout, and tremendous orbits. [1] The plates of the trunk shield are noticeably shortened: in Synauchenia , the trunk shield and head shield are fused together as a single, immovable unit. [2] The superficial anatomy of brachydeirids is extremely diverse, and each genus has been previously placed in their own monogeneric families. [1]

The brachydeirids, together with Leptosteus , make up the superfamily Brachydeiroidea.

Genera

Brachydeirus

The half a dozen species of Brachydeirus are comparable (on a superficial level) in form and size to trout or small mackerels. The biting surfaces of the infragnathals are smooth and thick, suggesting an adaptation for crushing. Species of Brachydeirus are all restricted to the Kellwasserkalk Fauna of Bad Wildungen and Adorf.

Oxyosteus

Oxyosteus is easily distinguished by a high, extremely compressed body and a long, thin rostrum. Two named species are known from the Bad Wildungen Kellwasserkalk Fauna, while a dorsal plate of an as of yet unnamed species is known from the middle Frasnian-aged portion of the Holy Cross Mountains of Poland.

Synauchenia

As mentioned earlier, Synauchenia is unique in the entire order for having the trunk and head shields fused together into an immovable unit. It is restricted to the Bad Wildungen Kellwasserkalk Fauna.

See also

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<span class="mw-page-title-main">Selenosteidae</span> Extinct family of fishes

Selenosteidae is an extinct family of small to large-sized arthrodire placoderms from the Late Devonian. With the exception of the Chinese Phymosteus, selenosteids lived in shallow seas in what is now Eastern North America, Eastern Europe, and Northeastern Africa.

<i>Draconichthys</i>

Draconichthys elegans a selenosteid arthrodire placoderm from the Late Frasnian Kellwasserkalk facies of the Anti-Atlas Mountains of what is now Morocco. During the Late Devonian, the region would have been a shallow, algae-dimmed sea.

<i>Selenosteus</i>

Selenosteus brevis is an extinct large selenosteid arthrodire placoderm known from the Famennian Cleveland Shale of Ohio. Scrappy remains from the Frasnian Rhinestreet Shales of Erie County, New York, were attributed by Hussakof and Bryant to this genus in 1919, but, this identification is doubtful. A second species, S. kepleri, was described in 1901, but, not enough differences can be seen between its specimens, and those of the type species to warrant new species status.

<i>Asterosteus</i>

Asterosteus is a genus of rhenanid placoderm from the Eifelian. The type species, A. stenocephalus, is known from an incomplete skull from Middle Devonian strata in Ohio. What may be a second species is described from fragments decorated with star-shaped tubercules from the Eifelian-aged Gebze beds of Turkey.

<i>Hadrosteus</i>

Hadrosteus is an extinct monospecific genus of large arthrodire placoderm from the Late Frasnian Kellwasserkalk facies of Bad Wildungen, Germany. It had large, double-pronged inferognathals, and serrated edges along its mandible, strongly suggesting that it was a fish-eating predator. The head had a triangular snout, and the trunkshield was short, but high, with a median dorsal plate that was broader than wide. The average skull length is about 16 centimeters.

<i>Stenosteus</i> Genus of fishes (fossil)

Stenosteus is an extinct monospecific genus of medium-sized selenosteid arthrodire placoderms of the Late Devonian period known from the Upper Famennian Cleveland Shale of Ohio. Estimated skull lengths range from 6 to 9 centimeters Most fossils of Stenosteus have been scraps of armor and portions of tooth-plates suggestive of Selenosteus. In 1996, enough material of a new species, S. angustopectus, was recovered to allow a reconstruction of armor that resembles that of Selenosteus.

<i>Gymnotrachelus</i> Genus of fishes (fossil)

Gymnotrachelus is an extinct monospecific genus of large selenosteid arthrodire placoderm of the Late Devonian known from the Late Famennian Cleveland Shale of Ohio. The type species Gymnotrachelus hydei was originally reconstructed as physically resembling Selenosteus, with slightly smaller orbits. Later specimens led to a reappraisal, and now G. hydei is thought to have a more gar-like or barracuda-like build.

<i>Microsteus</i>

Microsteus is an extinct genus of small selenosteid arthrodire placoderms known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Germany.

<i>Enseosteus</i>

Enseosteus is an extinct genus of small selenosteid arthrodire placoderms known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Germany and Morocco.

Erromenosteus is a genus of extinct, medium-sized brachythoracid arthrodire placoderm from the Late Frasnian of the Kellwasserkalk facies of Late Devonian Bad Wildungen and Bicken, Germany.

<i>Paramylostoma</i>

Paramylostoma arcualis is an extinct selenosteid arthrodire placoderm from the Late Famennian Cleveland Shale of Late Devonian Ohio. It has a compressed, box-like head and thoracic armor, and large, rounded orbits. However, in comparison with other selenosteids, such as Selenosteus, P. arcualis' orbits were rather small. P. arcualis had smooth jaws that suggest the animal was durophagous.

<i>Rhinosteus</i> Genus of fishes (fossil)

Rhinosteus is an extinct genus of small to medium selenosteid arthrodire placoderms of the Late Devonian known from the Upper Frasnian Kellwasserkalk facies of Bad Wildungen, Germany and Morocco.

<i>Braunosteus</i>

Braunosteus schmidti is a medium-sized selenosteid arthrodire placoderm known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Bad Wildungen, Germany. B. schmidti has a broad skull about 9 centimeters long, and a short, but pointed rostrum. Its appearance is very similar to that of the basal selenosteid Pachyosteus.

<i>Pachyosteus</i> Genus of fishes (fossil)

Pachyosteus is an extinct monospecific genus of medium-sized selenosteid arthrodire placoderm known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Bad Wildungen, Germany and from the Famennian portions of the Holy Cross Mountains of Poland. The type species Pachyosteus bulla has a broad skull about 7 to 10 centimetres long, a comparatively long median dorsal plate, and a short rostral plate that meets the pineal plate.

<i>Walterosteus</i>

Walterosteus is an extinct genus of small selenosteid arthrodire placoderms known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Germany and Morocco.

<span class="mw-page-title-main">Brachydeiroidea</span>

Brachydeiroidea is a superfamily of small to moderately large-sized arthrodire placoderms from the Late Devonian of Europe and Eastern North America.

<i>Brachydeirus</i>

Brachydeirus is a genus of small to moderately large-sized arthrodire placoderms from the Late Devonian of Europe, restricted to the Kellwasserkalk Fauna of Bad Wildungen and Adorf.

<i>Oxyosteus</i> Extinct genus of fishes

Oxyosteus is a genus of trout-sized, highly compressed arthrodire placoderms from the Late Devonian of Europe: The two described species are restricted to the Late Frasnian-aged Kellwasserkalk Fauna of Bad Wildungen, while a median dorsal plate of an unnamed species is known from the Middle Frasnian Holy Cross Mountains of Poland.

<i>Synauchenia</i>

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

References

  1. 1 2 Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 73. ISBN   9780895740274.
  2. Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 74. ISBN   9780895740274.