Fossil Friday – skull of “Little Stevie” the mastodon

 As promised, during our crowdfunding campaign to work on mastodons I’m featuring mastodons in all my Fossil Friday posts. This week is the partial skull of “Little Stevie” from the WSC collections. 

“Little Stevie” was the most complete mastodon found at Diamond Valley Lake, with about 40% of the skeleton recovered. Thanks to a donation by Eric and Gisela Gosch, most of “Little Stevie’s” skeleton is on display in a case embedded in the floor of the museum, but the partially prepared skull is in the collections. Below is a marked-up version of the image above:


The skull is laying upside down, and the yellow arrow is pointing anteriorly. That means you’re looking at the right side of the skull. The 2nd and 3rd upper molars are indicated in blue, and the right occipital condyle is labeled (the skull’s articulation with the first neck vertebra). The broken cheek bones are visible close to the camera, as are the internal choanae (the internal openings for the nostrils) just behind the 3rd molar. There are also a number of postcranial bones in the jacket, including several ribs (there’s one below the yellow arrow) and two thoracic vertebrae indicated by the red arrows. Both thoracic vertebrae are missing their epiphyses, indicating that “Little Stevie” was still growing. However, the femur associated with this skeleton has fused epiphyses, and at least the first two lophs on the third molar are in wear, which suggests that “Little Stevie” was close to full grown, maybe early to mid-20s.

We don’t know for sure if “Little Stevie” is a male or a female. The best markers for determining sex in a mastodon are the pelvis and the tusks, neither of which is well preserved in “Little Stevie” (although we may eventually be able to get a pelvic measurement). “Little Stevie’s” femur is very close to the size and proportions of the Java Site mastodon from New York, which is thought to be a female, but that’s not a very reliable indicator of sex.

“Little Stevie” does include both 2nd and 3rd molars and a femur, all of which are bones we’re examining in our mastodon study, so that means “Little Stevie” is included in our project. Help us collect more data to compare to “Little Stevie” by donating at experiment.com/mastodon.

 

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