Sauropods were those lengthy, lumbering dinosaurs with long necks and tails that you might imagine reaching up into tall trees for a delicious leafy treat or stomping through ancient forests à la Jurassic Park. These beasts needed massive amounts of greenery – they were vegetarians – to fuel their enormous bodies, which weighed up to 110 tons. If sauropods had had dentists, they wouldn’t have been happy about the wear and tear on their pearly whites. But sauropods had something better than dental care – they had replacement teeth that grew in when old teeth got worn out.
Michael D’Emic from Stony Brook University in New York and John Whitlock from Mount Aloysius College in Pennsylvania set out to delve deeper into sauropod dentition. In order to determine the rate at which teeth formed and how they were replaced, the scientists looked at thin slices of fossilized teeth from two sauropod species, Diplodocus and Camarasaurus. These tiny cross-sections show the rings of dentition that are continuously added to teeth during growth – think rings on a tree stump.
D’Emic and Whitlock found that Camarasaurus had a mouth that held up to 3 replacement teeth in each tooth cavity, so when one became worn down, it would fall out and a new one would pop up every 62 days. Diplodocus had even better adapted teeth- they regrew every 35 days and had up to 5 replacements waiting in the ready.
Though we might wish we had teeth like sauropods that renewed every so often, modern mammals do have a dental advantage that Diplodocus and Camarasaurus did not – strong enamel. The outer later of the teeth of sauropods was thinner and less hardy than ours – probably part of the reason their teeth came to be replaced so often. We evolved to have stronger teeth rather than replace ours. Evolution is a species-specific give and take: certain species develop certain adpatations to survive, while another species might not have that adaptation, but instead deal with the same stress in the form of a different adaptation.
D’Emic and Whitlock hope to study the dentition of other dinosaurs, perhaps looking into those of carnivores and other ancient creatures to explore more about the evolution of teeth.
Find the report on sauropods in the journal PLOS ONE.
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