Description:
This is a fine example of a rarely seen amphibian known as Discosauriscus.
While also known as Letoveterpeton, that name has been considered
a junior synonym. While once thought to be either a reptile or an
amphibian, the fact that examples are now known from the gilled
larval state places it firmly with the Amphibia. Given its affinities
with the North American Seymouria, it may have had a similar reptile-like
appearance as a mature adult. It is placed here in the Reptile section
of the mall as amphibians are almost never offered.
What
is most unusual about this specimen is that it has been painstakingly
prepared free of matrix to show only the skeletal and soft tissue
of the animal itself. This is a laborious process that involves
mechanical removal of matrix,
flowed by digestion with acid. The exposed elements are then protected
and the process iterated numerous times before the finished specimen
is embedded in a UV-resistant resin for display. Given there is
an 80-90 percent reject rate during the process few finished specimens
are ever offered. While expensive, when one considers some 250-300
man-hours over a period on 20 to 30 weeks the price is not that
outlandish.
This
particular example shows the skull and most of the articulated postcranial
elements including many parts of the limbs. On the dorsal side of
the skull you can make out the centrally-located “third eye”.
Known more accurately as the pineal or parietal eye. It possessed
a cornea, lens and a retina, and predominantly served a photoreceptive
function most likely tied to the circadian rhythm. Many reptiles
and amphibians still possess a rudimentary “third eye’
today. There is also quite a bit of skin adhering to the bones which
probably helped keep the specimen in an articulated state. Note
as well the teeth present on the right side of the head (seen on
left as this is a ventral view). Overall the best example I was
able to secure, similar to the one the preparatory recently placed
with the Czech National Museum.
See
other Discosauriscus fossil specimens here
and here.
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