Fossil Friday – bison molar

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As our molding and casting program gets underway, we’ve been going through the WSC collections looking for good candidates for molding. We’ve been particularly interested in teeth, because in many mammals the teeth are highly distinctive and potentially provide a lot of information about the animal. Over the last week we’ve been focusing on bison teeth.

Shown above is a more-or-less complete lower right molar from Bison, probably the 2nd molar, shown in labial view. Here’s the same tooth in lingual view:

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In this view there’s a ridge running vertically down the middle of the tooth called a stylid. This is a column of enamel that will show up on the occlusal surface of the tooth as a small ring of enamel if the tooth is sufficiently worn. This stylid seems to always be present in Bison, but in the closely related genus Bos (cows) the stylid is usually absent or only weakly developed.

Here’s the tooth in occlusal view:

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Bison have a selenodont tooth pattern with two main crescent-shaped cusps, similar to many other artiodactyls. The tooth is worn, but only slightly, so this animal was likely a young adult when it died. The tooth had not yet worn down as far as the stylid on the lingual surface, so the enamel loop isn’t visible; had the animal lived longer the loop would eventually have appeared as the tooth wore down.

This tooth was found near the east dam of Diamond Valley Lake.

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