The new specimen of Pelagiarctos thomasi (TATE 2694) collected by J.P. Cavigelli in 2012.
Preparator Sophie sculpts a pedestal onto the broken root of the tooth.
Morgan is down here in New Zealand and Australia for a two month EAPSI (East Asia and Pacific Summer Institute) fellowship, with the intent to utilize a statistical analysis to test the phylogenetic position of the problematic Pleistocene sea lion Neophoca palatina from New Zealand. About two months ago my labmate Carolina Loch-Silva suggested Morgan bring a Pelagiarctos tooth with him in order to secure an enamel fragment to examine its enamel structure - possibly as a way to take another stab at the feeding ecology of Pelagiarctos. To recap, Larry Barnes (1988) originally hypothesized Pelagiarctos to be a macrophagous 'killer' walrus, although our reevaluation of the data (Boessenecker and Churchill 2013) suggests that it was a dietary generalist like most modern pinnipeds, including robust sea lions.
The tooth on its pedestal.Even though Carolina's sampling method will not remove much of a tooth fragment, I was still interested in molding and casting the specimen. There are less than a dozen teeth of Pelagiarctos in museum collections (many more exist in private hands, which us researchers have to ignore for all intents and purposes), it would be useful to provide casts of the specimen to various west coast museums such as UCMP, LACM, the San Diego NHM, and the Cooper Center; casts of the specimen will also be sent back to the Tate Museum, the Smithsonian, and the National Museum of Nature and Science in Tokyo.
Mixing silicone and silicone catalyst requires careful measuring on a scale.
The tooth on its pedestal and base, with a single coat of silicone painted on to capture fine detail. Unfortunately, this coat never cured - we're using somewhat expired silicone, and it can be finicky when it cures, often requiring extra catalyst. We ended up pulling the rubber off and redoing it as a single pour.
The squalodontid tooth showing the acetate sheet dam. At this stage, once the silicone is mixed, it can be poured directly into the tube.
Both plug molds, with dental plaster freshly poured and waiting to cure.
Next up: pouring plaster and resin casts.