Birkenia
Birkenia is a genus of extinct jawless fish that lived during the Silurian period, approximately 443 to 419 million years ago. These ancient vertebrates are known from fossils found primarily in Scotland, particularly in the deposits of the Silurian of Oesel island. Birkenia were small, elongated fish, typically measuring only a few centimeters in length. They possessed a fusiform or torpedo-shaped body, adapted for swimming.
A notable feature of Birkenia was its dorsal fin, which was relatively large and prominent, providing stability
The fossil record of Birkenia indicates a relatively simple anatomy. They had a cartilaginous skeleton, as