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<em>Science Advances</em>: Teeth Gave <em>Triceratops</em> a Competitive Edge

A new analysis of Triceratops fossils reveals that the teeth of these iconic, three-horned dinosaurs were more complex than previously realized, rivaling the most advanced mammalian teeth, such those of horses and bison, in sophistication. The study appears in the 5 June issue of Science Advances.

The findings could help scientists better understand how these prehistoric animals adapted to exploit new diets and dominate among herbivorous dinosaurs.

The teeth included slicing structures and grooves similar to those seen on the sides of sword blades and fighting knives, both of which "allowed Triceratops to efficiently exploit plants that were not available to other herbivores," said Gregory Erickson, professor of anatomy and vertebrate paleobiology at Florida State University and co-author of the study. "This likely contributed to their remarkable ecological success."

Erickson, along co-author Brandon Krick, a mechanical engineering professor at Lehigh University and colleagues had previously shown that the teeth of other dominant herbivorous dinosaurs of the Late Cretaceous, the duck-billed hadrosaurids, were more complex than those of other reptiles. The researchers suspected the same was true for the horned ceratopsians, including Triceratops.

The authors analyzed fossil Triceratops teeth obtained from museums and performed analyses that included sliding a diamond-tipped microprobe across the fossilized teeth, to simulate the wear process during chewing.

"We utilized the same state-of-the-art instruments that we developed for measuring friction and wear of materials for space applications, lubricity of hydrogel contact lenses, and even interaction forces of cells and tissues," said Krick.

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Teeth in the lower jaw of a Triceratops fossil (C) show the centered groove in the tooth's biting surface, caused by self-wear. (View larger version) | Erickson et al Sci. Adv. 2015;1:e1500055/ AAAS

Combined with modeling analyses of wear rate, the authors found that Triceratops teeth self-wear, or break down due to chewing, grinding and biting over a lifetime, just like mammalian teeth do. Self-wear is less common in reptiles, but the process can help teeth change their shape to adapt to chewing certain kinds of foods.

Triceratops teeth self-wear, the authors argue, because the dinosaurs evolved five different dental tissues, each of which played specific biomechanical roles in the tooth wear process. One tissue, for example, had a very high wear rate that permitted bowled-out central regions to evolve in the teeth over time.

These recesses could have improved chewing efficiency by reducing the contact area between teeth and the plant matter being chewed. Evolving new dental tissues helped Triceratops expand its diet and dominate among large herbivorous dinosaurs.