We are lucky, in one way, in as much as we have multiple
associated elements from one animal and yet we have struggled to identify this
specimen, although we have now almost certainly identified this plesiosaur to
genus level. But with individual elements, or even parts of larger bones, you
can have much tougher problems with identification. Sure, there are elements
which can be assigned to, say, a plesiosaur or ichthyosaur but generic identification
is problematic.
But specific isolated elements can also be equally
diagnostic although I have found the identification of some marine reptile bones to
be particularly challenging. For example, plesiosaurs increased the amount of
phalanges in their limbs considerably over what is regarded as the standard
plesiomorphic condition. This is known as hyperphalangy and is characteristic
of plesiosaur limbs.
Phalanges all look alike and found in isolation are not
particularly helpful although some of the bigger ones are obviously pliosaurid
in origin. In contrast some other elements can often be identified to generic
level and cryptoclidid humeri are particularly useful in this respect. It’s
interesting that there are almost certainly odd elements in collections all
over the world that not only represent missing elements from known taxa but
also unknown elements from unknown taxa.
Again, Spinops comes to mind.
That aside, here are a set of proximal carpals from our
plesiosaur all finished with and prepared. These are, from left to right, the ulnare, intermedium
and radiale and are from the same forelimb featured in previous blog posts and
I am now working on the distal carpals. After that, there are the first five
metacarpals to prepare and then this particular forelimb will be finished – the
remaining part of the limb has long since vanished. Shortly after I will
publish a brief description and then this particular project will be
temporarily shelved because of other projects but eventually the next element
up for preparation is a rather impressive femur and, of course, I will publish
posts along the way.
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Ventral view |
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Dorsal view |
2 comments:
Hi Mark my name is Darren Withers . Have we both met at Must Farm Clay Pit in Whittlesey . Searching for Marine Reptiles around Bed 10.
Hi Darren. Yes we've met a few times before - glad you've found the blog!
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