The Dimetrodon may have been the first land-based carnivore to develop teeth designed like steak knives. Known as serrated ziphodont teeth, and these may have made this creature one of the most frightening of all ancient animals.
Such serrated teeth would have made the bite of Dimetrodon highly-efficient, allowing the animals to take down prey much larger than itself. This variety of tooth is common among meat-eating dinosaurs, such as Tyrannosaurus rex (or T. rex), known as theropods. But, Dimetrodon possessed this feature 40 million years before it became common in other species.
The new study was undertaken by Robert Reisz and graduate student Kristin Brink at the University of Toronto Mississauga. Fossils of Dimetrodon skulls and jaws were examined by several tools, including an electron microscope. Specimens from more than 25 million years of evolution were examined over the course of the study.
Dimetrodons, with their distinctive sail-like feature on their backs, were an early forerunner to mammals. They were a top-level feeder during the Permian period, with few predators able to challenge their might. Researchers question the purpose of this large sail. Some theorize the animals used the distinctive feature to heat and cool their cold-blooded bodies. Other postulate the sails were used as a means to attract members of the opposite sex.
Reisz and Brink were able to uncover evidence the species had a wide range of previously unknown structures within its teeth. One unexpected find were teeth with cusps - raised points on teeth, which are common in mammals.
"This research is an important step in reconstructing the structure of ancient complex communities. Teeth tell us a lot more about the ecology of animals than just looking at the skeleton," Reisz said. "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."
Dimetrodons were more like mammals than dinosaurs, and are members of a class of animal known as Pelycosaur. This class of animals is often mistaken as a dinosaur, but evolved 50 million years before dinosaurs walked the land.
The researchers believe serrated teeth evolved late in the evolution of the animals, due to the fact the rest of their skulls remained unchanged. Earlier fossils of the species show non-serrated ziphodont teeth. This change suggests Dimetrodons may have been the first animal to develop this adaptation. It could also help paleontologists discover patterns in how the animals lived.
Dimetrodons walked the Earth between 298 and 272 million years ago. Adult specimens grew to be over 12 feet long.
Research into the anatomy of Dimetrodons was funded by the Natural Sciences and Engineering Research Council (NSERC), and published in the journal Nature Communications.
