Sunday, November 24, 2013

Proof of multiple skeletons - another type of backbone

It looks like we have some proof of a second type of animal's bones in our specimens. So the dilemma of the week is: what do we call this pair? Bernie and Ernie? Bert and Ernie? Bernie and Bertie?

We have prepared a second type of backbone that is very different from the squished hockey-puck centrums typical of Ichthyosaurs. We have quite a few of the latter type which is what led us to believe we had an Ichthyosaur in the first place. It is about 57mm long by 44mm wide. No processes (spurs) are evident, and I don't see where they would have been if they got worn off. It does have very nice zygapophyses, the interlocking parts between the backbones. There is a large crack across the bone, filled with substrate(coarse sandstone& chert chips) , so it broke during burial. This crack is evident as a broad curved line in picture #1. The squares on the card are 1/4 inch.
Here's the pictures:

Ichthyosaur-type backbone for reference:

 At this point I'll predict that the new type of backbone belongs to the skull, which doesn't look like an Ichthyosaur either. Hopefully we'll have some more backbones of this second animal as we go. Some of the limb bones might be from this second animal as well. The limb bones prepared to-date have hollow ends, indicating the animal was not mature. However we have at least two bones in the matrix that have rounded ends that are not hollow. These would go with the second animal, I believe.

On the original animal, we have previously prepared a Humerus  (or Femur). We now have a second similar bone that is slightly shorter. It also has an interesting ridge across one end that the first bone does not have. So I'll predict that we have the Femur to go with the original Humerus. This means the Ichthyosaur-type animal had 4 distinct limbs, like a lizard-shaped Ichthyosaur like Cymbospondylus. It's not completely prepared, so I'll post pictures of both bones next time.
Have a happy Thanksgiving for those in the US!
Sincerely, Greg Carr

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