Dinosaur

Theropods were an immensely diverse group of dinosaurs that thrived in the Jurassic and Cretaceous periods. Today, they live on as toothless birds; chickens now are, fortunately, quite unlike the Velociraptor that tore apart its prey with 26 widely spaced teeth. Dinosaur dentistry is the focus of a new Current Biology study on theropods, which shows that if you want to know what prey theropods ripped into, the answer is in the bite.

Previous analyses of theropod teeth dating to the Upper Cretaceous period (100.5 to 66 million years ago) showed that these predators used a “puncture-and-pull bite strategy” to kill and consume prey. With blade-shaped dentures, they’d feast like you would cut into bread with a serrated knife — pushing down, then ripping through. But while all of the dinosaurs in the Theropod family may have used similar feeding movements, a team of scientists announced Thursday in the new paper that the angle in which they bit into a meal reveals that different species went after different victims — some choosing larger, weakened prey and others preferring softer, smaller critters.

Theropod teeth
Microwear patterns on the teeth of three theropods. 

“All these dinosaurs were living at the same time and place, so it is important to know if they were competing for food resources or if they were aiming for different prey,” co-author and Universidad de La Rioja postdoctoral fellow Angelica Torices, Ph.D. explained in a statement released Thursday. “We find that, in general, predatory coleurosaurian dinosaurs bite in the same way through a puncture-and-pull system, but troodontids and dromaeosaurids may have preferred different prey.”

Torices and her team came to this conclusion by examining the patterns of small scratches on the teeth of theropods, a form of damage called microwear. Their observations established that there were specific patterns in the ways that the dinosaurs ate. Taking that data and inserting it in a modeling approach called finite elements analysis, they figured out how the teeth would have worked when used at different cutting angles.

Clades of bird-like dinos called Dromaeosaurus and Saurornitholestes, they discovered, adapted their bite to handle struggling prey and even used their teeth to process the victim’s bones as they chowed down. Meanwhile, troodontids — small, long-legged theropods — couldn’t bite as successfully at the awkward angles required to take down struggling prey, and so they likely preferred softer, invertebrate prey that “required a less powerful bite or could be swallowed whole.”

Next up for this team is creating more complex biting process models, that will incorporate the strength of the dinosaur’s jaws. This way, scientists will have a better idea of the sort of food-chain that went down millions of years ago — and we’ll know, if dinosaurs are ever created in labs, who they’re going to want to bite first.