Ancient Tetrapod Tyrannoroter Reveals Early Herbivory in Land Animals

307-million-year-old fossil skull shows one of the earliest land animals experimented with plant-based diet

Published on Feb. 10, 2026

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A newly discovered fossil skull from Nova Scotia, Canada, reveals that one of the earliest land animals, Tyrannoroter heberti, was among the first tetrapods to experiment with a plant-based diet, according to a study published in the journal Systematic Palaeontology. The 307-million-year-old fossil, unearthed within a fossilized tree stump, belonged to a creature roughly the size of an American football and represents a significant shift in understanding the dietary evolution of early terrestrial vertebrates.

Why it matters

This discovery provides direct evidence that herbivory arose quickly following the initial terrestrialization of tetrapods, revising the timeline of the origin of plant-based diets in early land animals. It shows that experimentation with herbivory goes back to some of the earliest four-legged creatures, shedding new light on the dietary evolution of vertebrates.

The details

Researchers at the Field Museum and Carleton University utilized high-resolution micro-CT scanning to analyze the skull's internal structure, revealing a unique dental arrangement. Beyond the typical teeth, Tyrannoroter possessed bony plates, known as dental batteries, on both the roof of its mouth and in its lower jaw. These plates would have functioned by grinding against each other, effectively breaking down tough plant matter - a feature later seen in herbivores like dinosaurs. The researchers suggest Tyrannoroter may have supplemented its plant-based diet with insects and other arthropods, as the dental batteries may have initially evolved to process exoskeletons before adapting to grind plant material.

  • The 307-million-year-old fossil was unearthed within a fossilized tree stump in Nova Scotia, Canada.
  • The study was published on February 10, 2026 in the journal Systematic Palaeontology.

The players

Tyrannoroter heberti

One of the earliest land animals, a 25-centimeter-long creature that was among the first tetrapods to experiment with a plant-based diet.

Arjan Mann

Evolutionary biologist at the Field Museum and co-lead author of the study.

Hillary Maddin

Paleontologist at Carleton University and senior author of the study.

Field Museum

The research institution in Chicago that co-led the study on the Tyrannoroter fossil.

Carleton University

The Canadian university that co-led the study on the Tyrannoroter fossil.

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What they’re saying

“This is one of the oldest known four-legged animals to eat its veggies. It shows that experimentation with herbivory goes all the way back to the earliest terrestrial tetrapods – the ancient relatives of all land vertebrates, including us.”

— Arjan Mann, Evolutionary biologist, Field Museum (world-today-news.com)

“We were most excited to see what was hidden inside the mouth of this animal once it was scanned – a mouth jam-packed with a whole additional set of teeth for crushing and grinding food, like plants.”

— Hillary Maddin, Paleontologist, Carleton University (world-today-news.com)

What’s next

Paleontologists plan to further investigate the ancient ecosystem in which Tyrannoroter lived to determine the exact species of ferns or other plants it consumed.

The takeaway

This discovery revises the timeline of the origin of herbivory, showing that various herbivorous forms arose quickly following the initial terrestrialization of tetrapods. It provides direct evidence that early land animals experimented with plant-based diets much earlier than previously thought.