Friday, July 26, 2013

4th Update - Bernie's Got Teeth!!

Bernie’s got Teeth!!! – and other finds

This report covers the period from May 18th to June 17th, 2013
The highlight of this period, as noted above, is that a fragment of jaw with imbedded teeth has been found! This means that we do have some of Bernie’s skull, even if in fragments, and the teeth are certainly diagnostic.  The teeth are imbedded in their own individual sockets . This dental structure is termed Ichthyosaur Thecodont (R Motani) . We don’t know if the teeth are fused to the jawbone at the bottom or not – it will take an X-ray or CAT scan to determine that.. This is unusual for Ichthyosaurs, where the teeth are usually imbedded in a long groove along the jawbones especially for all Jurassic and Cretaceous Ichthyosaurs. The broken face of the bone was actually exposed on the surface of the concretion, so we know it’s long gone. In the picture below, the left side of the jaw is the distal end of the jaw – end furthest away from the skull.

Having the teeth in individual sockets limits Bernie’s families to the known Cymbospondylus and Shonisaurus or an unknown lineage. Both of these are found in Triassic Nevada though the Cymbospondylus has not been found in the Carnian age, which Bernie’s formation is dated.

One side of the jaw has some funny-looking bone, rather porous and irregular. It may be some preserved cartilage or who knows – old injury site perhaps? 
Other great finds worked on this period is a possible Graphaea, or oyster-like animal. However, this shell has two ‘wing’ projections out the side where all the descriptions of Graphaea do not show these. Perhaps it's a pearl oyster instead - Dr Retallak at the U of Oregon gave this suggestion - Your bivalve is not Gryphaea, but more like Pteroperna cf. P. plana (a common species in the Pliensbachian Robertson Formation)

We are starting to work out this thin blade of bone. Further work (see the next entry) shows this is a very complete scapula. The notches on the edge are from some bone that broke off with the covering rock, which came away in one piece. We have them & will re-glue them back on. Number one rule in Paleontology - KEEP ALL THE PIECES!!!!!
Further work (see next post) suggests this may be part of the skull - 

Last, we have a great Nautiloid starting to be removed. It’s over 11 cm in diameter, and one side is apparently uncrushed. It’s going to be beautiful:

It’s hard to get a full picture as it’s very close to one of the shoulder girdle bones shown above This block contains three other incomplete Nautiloids, and part of another one that could be complete – the rest is in another block. I still think the Nautiloids were eating Bernie’s carcass when they were all buried – this may explain why we have so many in one small spot.

More to come……..

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