Birkenia

Birkenia; Temporal range: Late Llandovery to ?Late Lochkovian
	Birkenia elegans
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Anaspida
Order:	Birkeniiformes
Family:	Birkeniidae
Genus:	Birkenia; Traquair 1898
Type species
	Birkenia elegans; Traquair 1898
Species
	B. campbelli Traquair 1898; B. elegans Traquair 1898; B. robusta Blom, Märss et Miller 2002;

Birkenia is a genus of extinct anaspid fish from Middle Silurian strata of Northern Europe, and Middle Silurian to possibly Earliest Devonian strata of Arctic Canada.[1] Birkeniid anaspids are covered by a series of small plates on the head and rod-shaped scales in a cheveron-like pattern on the trunk.[2]

Fossil and model of B. elegans

Intact fossil specimens of B. elegans suggest the living animal reached a length of up to 10.0 cm (3.9 in), and was an active swimmer. In addition to whole specimens and scale microfossils of B. elegans, which are found in Great Britain and Scandinavia,[3] scales of a second species, B. robusta,[1] are found in Late Silurian strata of Scandinavia and Estonia. The scales of B. robusta differ from those of B. elegans in that, as the specific epithet suggests, the scales of the former are more robustly proportioned than those of the latter. Fossil specimens also show a rib that is modified by being narrow at the ends and gradually broadens and rises towards the middle of the scale, where a major elevation is developed that is expressed as a raised and slightly angled ridge. [2]

References

Blom, Henning, T. Märss, and C. G. Miller. "Silurian and earliest Devonian birkeniid anaspids from the Northern Hemisphere." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 92.03 (2001): 263-323.
Blom, Henning (May 2012). "New birkeniid anaspid from the Lower Devonian of Scotland and its phylogenetic implications". Palaeontology. 55 (3): 641–652. doi:10.1111/j.1475-4983.2012.01142.x.
Dineley, David L. & Metcalf, S. J. (1999). Fossil fishes of Great Britain (Volume 16 of Geological conservation review series). Joint Nature Conservation Committee. pp. 38, 46 (675). ISBN 9781861074706.

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[Blomm-1] Blom, Henning, T. Märss, and C. G. Miller. "Silurian and earliest Devonian birkeniid anaspids from the Northern Hemisphere." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 92.03 (2001): 263-323.

[:0-2] Blom, Henning (May 2012). "New birkeniid anaspid from the Lower Devonian of Scotland and its phylogenetic implications". Palaeontology. 55 (3): 641–652. doi:10.1111/j.1475-4983.2012.01142.x.

[fossilsfish-3] Dineley, David L. & Metcalf, S. J. (1999). Fossil fishes of Great Britain (Volume 16 of Geological conservation review series). Joint Nature Conservation Committee. pp. 38, 46 (675). ISBN 9781861074706.