Birkenia is a genus of extinct anaspid fish from the Late Silurian to the Early Devonian of Europe. It reached a length of 4 in (10 cm) and was an active swimmer.

  Birkenia has a characteristic row of anterior and posterior pointing dorsal scutes. Approximately on the middle of the back there is a larger scute pointing anterior as well as posterior. In front of the head there is a round patch containing tiny scales. A row of slanting round gill apertures lead to the gill chambers, so the fish could take oxygen independently of the mouth. The tail is hypocercal, which means that the lower lobe is the longest. This has confused Traquair when he initially described this fish because he never met this conditon and therefore reconstructed Birkenia upside down. Well preserved specimens show an anal fin anterior to the tail.

 Birkenia was adapted for active swimming, and its sucking mouth was in a terminal rather than a ventral position. The head of Birkenia was covered by small scales rather than by the fused bony shield of some of its relatives.

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Tags: Вымершие бесчелюстные, Силур

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