Scientists have identified a 307-million-year-old fossil as one of the earliest known land vertebrates to consume plants. The creature, named Tyrannoroter heberti, featured specialized teeth for grinding vegetation. This discovery challenges previous understandings of early terrestrial diets.
Hundreds of millions of years ago, vertebrate animals began transitioning from sea to land, initially relying on meat-based diets despite the spread of plants. A new study published in Nature Ecology and Evolution describes Tyrannoroter heberti, a fossil from 307 million years ago that indicates some early land vertebrates experimented with herbivory.
The specimen, discovered on Cape Breton Island in Nova Scotia, consists of a skull found inside a fossilized tree stump by avocational paleontologist Brian Hebert during a field season led by Hillary Maddin of Carleton University. Named after its discoverer—meaning "Hebert's tyrant digger"—the animal was estimated to be about a foot long, with a stocky build resembling an American football. Arjan Mann, assistant curator at the Field Museum in Chicago and co-lead author, described it as "one of the oldest known four-legged animals to eat its veggies."
Classified as a pantylid microsaur and a stem amniote, Tyrannoroter lived before the divergence of reptiles and mammals. CT scans revealed specialized teeth inside its closed mouth, including palatal teeth suited for crushing and grinding plant material. Zifang Xiong, a PhD student at the University of Toronto and co-lead author, noted that "the specimen is the first of its group to receive a detailed 3D reconstruction, which allowed us to look inside its skull and reveal its specialized teeth."
While not a strict herbivore, the animal likely had a mixed diet including insects and plants. This adaptation occurred near the end of the Carboniferous Period, amid rainforest collapse and global warming. Mann highlighted that such changes could provide insights into how plant-eating animals responded to environmental shifts, as the lineage of Tyrannoroter did not fare well afterward.
Hans Sues, co-author from the Smithsonian National Museum of Natural History, emphasized that the fossil shows herbivory in stem amniotes earlier than thought, with dentition adapted for processing plant fodder.