Birkenia
elegans
Class Agnatha,
Order Anaspidiformes
Geological
Time: Upper Silurian
Size: Fish
fossil is 55 mm in length by 22 mm high on a 42 mm by 39 mm matrix
Fossil Site:
Leshmagow, Scotland
Fossil Code:
UKF230
Price: Sold
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 Silurian
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, not
visible in this dorsal example. This one is quite rare in that
it displays features that appear to be eyes. They are actually
posterior to the eyes which would be on the sides of the body
and are known as the otic capsules. An otic capsule, also known
as the bony labyrinth, is the bone surrounding the organs of
balance. This is the first such example I have come across. Any
specimen of the ansapids is highly prized, so one displaying
this much detail will surely be a trophy piece for any collection.
See my other offerings for an unusual part/counterpart specimen.
Also
see: Paleozoic
Fish Fossils |
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