Wednesday, March 29, 2023

Updates from the CCNHM prep lab 5: the complete auditory region of a 26 myo baby dolphin (Olympicetus)

An update on a partial skull of the early dolphin Olympicetus avitus. This specimen was previously mentioned in an earlier blog post, here. This is the final bit of preparation of JLG 387 - a small, unnasuming nodule from the Pysht Formation, collected from the north shore of the Olympic Peninsula by Jim Goedert and donated to us back in 2016 - one of the earliest donations of his. This specimen already had a nice partial bulla, and some teeth, but I really wasn't expecting anything quite this nice - a completely articulated squamosal, bulla, and periotic! The nodule was quite small - only a few pounds.

After some rinsing, I dried the squamosal complex out and used a dental pick and some brushes to clean off some of the dried mud matrix. Most of the calcareous matrix dissolves, but the inorganic silt is left behind and softened considerably - and I do blast much of it off with a water hose and also brush it away with a toothbrush, but there is always a bit of mud that is left behind in cracks and delicate areas.

The whole complex in dorsomedial view (left) and ventrolateral view (right).

The specimen in true dorsal view (left) and lateral view (right).

And a couple more views: posterodorsal (left) and anteromedial (right).

And to help, here is the squamosal in yellow, periotic in red, and the bulla in blue.

 All in all quite a nice specimen - the isolated teeth and the tympanic bulla will help confirm that this is Olympicetus avitus - one of many specimens we have with a periotic, which is not preserved in the holotype specimen. Now that everything is prepared and consolidated, I need to bring this into the collections room so Sarah can make a nice cavity mount for it and get it catalogued into the collection. Huge thanks to Jim for picking up this cute little concretion and mailing it to us! Next up: I need to get this into the hands of Rachel Racicot so she can run it through a micro-CT...

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