A newly discovered fossil skull from Nova Scotia is rewriting the timeline of when land animals began eating plants. This 307-million-year-old skull, found by avocational paleontologist Brian Hebert, belongs to one of the earliest known land vertebrates capable of handling plants. The discovery, led by scientists from the Field Museum, the University of Toronto, Carleton University, and the Smithsonian National Museum of Natural History, challenges long-held beliefs about the evolution of herbivory in terrestrial animals.
The skull, named Tyrannoroter heberti, was found within a fossilized tree stump on Cape Breton Island. It's estimated to be about a foot long and shaped like an American football. The team used CT imaging to create a 3D model, revealing specialized teeth designed for crushing and grinding tough plant material. This discovery suggests that the experimentation with herbivory dates back to the earliest terrestrial tetrapods, the ancient ancestors of all land vertebrates, including humans.
The fossil's mouth was fossilized shut, but the team's 3D reconstruction helped them identify the teeth's arrangement, which was similar to a grinding tool kit. These teeth, including those on the roof of the mouth, could process mature leaves and stems. The strong lower jaw, with a massive tooth near the back, further supports the animal's ability to handle tough plant matter.
This finding challenges the idea that widespread plant eating among land animals only began during the Permian period. It suggests that early land vertebrates tried plant-heavy diets sooner and in more lineages than previously thought. This discovery has practical implications for understanding early food webs and the evolution of diet shifts in land animals, including the role of teeth, jaws, and gut microbes.
The research also highlights the importance of tooth patterns in signaling diet, even when stomach contents are not preserved. This discovery adds to our understanding of how plant-eating animals respond to rapid ecosystem changes, such as the collapse of rainforest ecosystems and periods of global warming.
