| Name:
Agnatha; Anaspidiformes; Birkenia elegans
Age: Upper
Silurian
Size (25.4
mm = 1 inch): 34 mm in length on 90 mm by 62 mm matrix
Location:
Seggholm, Muikirk, Ayrshire, Scotland
|  Description:
The Anaspids were simple dorso-laterally compressed fish that probably
led a bottom-dwelling existence. Their main common feature was a
jawless mouth. Indeed the name means without jaws. They were mostly
quite small fishes that flourished during the Silurain and Devonian
that then became extinct except  for
their modern-day relatives the Lampreys and Hagfishes. The gills
opened as a row of holes along the side of the animal, typically
numbering from 6-15. One unusual example from Canada holds the record
for gills at 30 pairs! They probably behaved much like the lampreys,
and most lived in freshwater environments. This fine example is
known as Birkenia. It had an elaborate array of dorsal scales, some
of which are seen here. Complete examples of the Anaspida are quite
rare; the repaired crack does little to detract from this exceptional
specimen. All the diagnostic features of the taxon are displayed
within this high-quality specimen that came from a 50 year old collection.
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