Carnivorous, Pre-Dinosaur Predator was First to Evolve Steak Knife-like Teeth

A carnivorous animal that roamed the Earth about 285 million years ago was the first terrestrial vertebrate to develop the curved, serrated teeth that enable a predator to eat prey much larger than itself, according to paleontologists at University of Toronto, Mississauga.

These curved, steak knife-like teeth - otherwise known as ziphodont teeth - were first evolved by the Dimetrodon, a predator of the Early Permian era that went extinct about 40 million years before the first dinosaurs appeared in the Triassic period.

Most carnivorous dinosaurs possessed ziphodont teeth, but Dimetrodon (which is not considered a dinosaur) provides evidence that such teeth evolved in land animals that preceded the earliest dinosaurs.

"Technologies such as scanning electron microscopes and histology allowed us to examine these teeth in detail to reveal previously unknown patterns in the evolutionary history of Dimetrodon," said Kirstin Brink, lead author of a study detailing the Dimetrodon teeth in the journal Nature Communications.

Dimetrodon is considered to be the forerunner of mammals, Brink and her colleague Robert Reisz said. That belief that is corroborated by another feature of the creature's teeth: cusps. According to the researchers, cusps - raised points on the crown of teeth - are dominant in mammals and Dimetrodon provided the earliest evidence of cusps in a terrestrial vertebrate.

"This research is an important step in reconstructing the structure of ancient complex communities," Reisz said. "We already know from fossil evidence which animals existed at that time but now with this type of research we are starting to piece together how the members of these communities interacted."

"Teeth tell us a lot more about the ecology of animals than just looking at the skeleton," he added.

The shape of the Dimetrodon's teeth, the researchers contend, was more of reflection of changes in their environment and feeding style than any morphological changes to their skulls and jaws.

"The steak knife configuration of these teeth and the architecture of the skull suggest Dimetrodon was able to grab and rip and dismember large prey," Reisz said. "Teeth fossils have attracted a lot of attention in dinosaurs but much less is known about the animals that lived during this first chapter in terrestrial evolution."