Dimetrodon had a mouth full of novelty. Most conspicuous were several different tooth types in the sail-backed protomammal’s jaws – incisor-like teeth for gripping, stabbing canines, recurved rear teeth for shearing through flesh, and even hidden teeth on the roof of the mouth to pin struggling prey. This combination of features, shared by other members of the sphenacodontid group to which Dimetrodon belonged, originated with such predators as they thrived between 298 and 272 million years ago. And particular species of Dimetrodon even added a new wrinkle to the enamel-based armaments. As described by University of Toronto Mississauga paleontologists Kirstin Brink and Robert Reisz in a new Nature Communications paper, Dimetrodon is the earliest known land-stalking carnivore to have bitten through flesh with serrated teeth.