Plant-eating dinosaurs replaced teeth often, carried spares

Jul 17, 2013

Some of the largest herbivorous dinosaurs replaced their teeth at a rate of approximately one tooth every 1-2 months to compensate for tooth wear from crunching up plants, according to research published July 17 in the open access journal PLOS ONE by Michael D'Emic from Stony Brook University and colleagues from other institutions.

A little like counting tree rings, researchers can estimate rates of tooth formation and replacement in by counting lines of deposition of tooth dentin, a layer below enamel that grows throughout an animal's life. In this study, authors estimated tooth replacement rates in Diplodocus and Camarasaurus, two distantly related, different-looking of similar giant size. Camarasaurus had up to three "baby teeth" lined up in each tooth socket, and replaced about one tooth every 62 days. Each Diplodocus tooth socket held up to five replacement teeth and one functional tooth, and each tooth was replaced once in 35 days.

This video is not supported by your browser at this time.
This is a CT-generated movie of the premaxilla of Diplodocus (YPM 4677), with bone rendered transparent and teeth opaque. Credit: D'Emic MD, Whitlock JA, Smith KM, Fisher DC, Wilson JA (2013) Evolution of High Tooth Replacement Rates in Sauropod Dinosaurs. PLoS ONE 8(7): e69235. doi:10.1371/journal.pone.0069235

As D'Emic explains, "A nearly 100-foot-long sauropod would have had a fresh tooth in each position about every one to two months, sometimes less. Effectively, sauropods took a 'quantity over quality' approach to making teeth, opposite the approach taken by large animals —mammals—today."

These sauropod dinosaurs were the largest terrestrial herbivores known, and would have required huge food supplies. Eating large amounts of plant foods likely caused extensive tooth wear, requiring this constant growth and replacement. Differences in the rates at which these species replaced their teeth could reflect differences in their feeding strategies or food choices.

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More information: PLoS ONE 8(7):e69235. doi:10.1371/journal.pone.0069235

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rwinners
1.5 / 5 (2) Jul 17, 2013
And?

Crocks, snakes and other thingies with teeth do the same thing today.
nkalanaga
5 / 5 (1) Jul 18, 2013
True, but most, if not all, animals that routinely replace teeth today are carnivores. What seems to be new here is that these are herbivores.
Sinister1811
1 / 5 (4) Jul 18, 2013
Most reptiles and certain fish/sharks replace their teeth. We could conclude a similar thing for dinosaurs. So far, the only mammals known to replace teeth are elephants and manatees.
nkalanaga
5 / 5 (1) Jul 20, 2013
Do elephants actually replace their teeth, or do the back molars move forward to fill the gaps left by the front ones wearing faster? I've heard that an adult elephant, like a human, only has one set of teeth, but that they use them in sequence.

As for manatees, you may be right. All I know about them is that they live in water...
Sinister1811
2 / 5 (4) Jul 20, 2013
@nkalanaga Yeah, you're right. I just looked it up on Google, and apparently it's the same for both animals - they have molars that move forward.

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