Filling in the Pacific Northwest

After obtaining measurements a few weeks ago from Alaska and Yukon mastodon teeth, it became clear that it would be necessary to examine additional specimens from the Pacific coast states. All of the California specimens currently in out database are from Southern California (Riverside, Orange, and Los Angeles Counties). They all have similar proportions, but they're quite different from the ones from Alaska and the Yukon. How far north do we have to go before this change occurs?

To address this question, I'm taking this week to visit two additional museums; the University of California - Berkeley's Museum of Paleontology and the University of Washington's Burke Museum of Natural History. Today I was at UCMP.

The UCMP mastodon collection is small, but geographically diverse within California. I was able to measure teeth from 7 California counties not previously represented in the database, as well as additional Rancho La Brea specimens, and even a cast of a Texas tooth. Most of the new specimens are from the San Francisco Bay area, the Central Valley, and the Sierra Nevada foothills, all hundreds of miles north of Rancho La Brea and Diamond Valley Lake. And the preliminary data says ... the Northern California teeth have the same proportions as the Southern California ones.

One of the nicer specimens is a palate from a young adult, probably a female, from Alameda County:

 

This tooth (a lower m3) from Tuolumne County is one of the longest mastodon teeth known from California:

 

One specimen that wasn't included was a partial lower jaw from San Benito County (the right dentary is shown below, but the left is also preserved):

 

One of the m3s in this specimen was over 207 mm long, the longest mastodon molar ever reported from California (by almost a centimeter!). Unfortunately, the 2nd lophid (usually the widest part of the tooth) is damaged in both m3s, so I was not able to get a maximum width. But the other lophid widths indicate that this tooth would have been typically Californian with a length:width ratio greater than 2.0.

Thanks to UCMP and Pat Holroyd for accommodating my visit! In a few days I'll be at the Burke Museum. As always, for more up-to-the-minute updates follow @MaxMastodon on Twitter.