Fossil Friday – mastodon thoracic vertebra

As I’m in the middle of our Mastodons of Unusual Size data-collecting trip, my Fossil Friday post will have to be a short one. But, in keeping with our road trip topic, it will of course feature a mastodon!

The specimen shown above is an anterior thoracic vertebra, shown in anterior view. The image is turned sideways to fit better on the screen, so the bottom of the vertebra is on the left. The bone is still in its field jacket, and has only been partially prepared.

Thoracic vertebra in mammals are the ones that articulate with the ribs, and the articulations are visible on the ends of the processes projecting from each side of the vertebra. The tall neural spine extends from the top of the vertebra (right in the photo). The neural spines serve in part as muscle attachment points for muscles that hold up the head and help support the front legs. In quadrupedal animals with large, heavy heads, such as mastodons, the anterior neural spines are very long, providing more surface area and better leverage for those muscles.

This vertebra was collected from the Diamond Valley Lake East Dam, close to where the Western Science Center is now located.


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