Fossil Friday – mastodon palate


Taphonomy is the subset of paleontology that examines how an organism gets preserved as a fossil. Taphonomists consider all kinds of different features, including the structure and composition of the organism, how and where it died, rates of sedimentation, the quantity and chemical composition of groundwater in the area, and countless other variables. Understanding taphonomy can tell us a great deal about an organism and its environment, and it’s something to be considered when looking at unusual preservation.

The specimen shown here is the partial palate of a mastodon, seen in palatal view (looking up at the roof of the mouth). All that remains are the crowns of the teeth and few bits of the maxillary and palatine bones. I’m not sure why this specimen preserved this way, but there are some possibilities to consider. By far the best preserved portions are the crowns of the teeth. Tooth enamel is generally the hardest and most chemically resistant part of the vertebrate body, so it’s not entirely surprising to see teeth surviving while the rest of the skeleton deteriorates.

This specimen has both left and right teeth preserved, in their correct life positions relative to each other, even though most of the bone between them is gone. That means the upper jaw survived as a unit for at least some period of time. Perhaps the skull was sitting on the ground in such a way that the upper jaw was buried but the rest of the skull was exposed and eroded away. Maybe when the animal was rotting or scavenged, the maxillae separated from the rest of the skull. Or maybe the skull was largely intact when it was buried but groundwater mostly dissolved the bones and left the teeth behind (we have a horse in the collection that may have experienced this).

As for the mastodon itself, the specimen is oriented with anterior to the left, so the left teeth are at the top and the right teeth are at the bottom. Portions of the crowns of both upper 2nd molars are preserved, and the left one is almost complete. The crowns of both upper 3rd molars are also preserved. The 2nd molars show heavy wear, but the 3rd molars show very little wear, and only on the anterior part of the tooth. This suggests a mastodon that was probably in its early 20s when it died.

As a reminder, tomorrow is the 2nd Annual Inland Empire Science Festival at the Western Science Center. Come to the museum to for tons of science-themed activities, lectures, and exhibits. Student, youth, and under-4 admissions will receive a coupon for a free replica Tyrannosaurus tooth, molded from a specimen on exhibit at the museum.

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