210 million years ago, the world’s top two predators, phytosaurs and rauisuchids, ruled the world. Until today, it was believed the two predators didn’t see too much of each other. Phytosaurs ruled the oceans, while rauisuchids stuck to the land.

Today, one tooth is changing that notion.

“Phytosaurs were thought to be dominant aquatic predators because of their large size and similarity to modern crocodylians,” said Michelle Stocker, a paleontologist at Virginia Tech, “but we were able to provide the first direct evidence they targeted both aquatic and large terrestrial prey.”

A tooth from a phytosaur was found in the thigh bone of a rauisuchid. The massive tooth was buried about two inches deep in the bone and had healed over. This indicated the rauisuchid survived the phytosaur meeting.

“Finding teeth embedded directly in fossil bone is very, very rare,” said Stephanie Drumheller of the University of Tennessee. “This is the first time it’s been identified among phytosaurs, and it gives us a smoking gun for interpreting this set of bite marks.”

Sterling Nesbitt, also a paleontologist at Virginia Tech, touched on how some discoveries can be overlooked. “We came across this bone and realized pretty quickly we had something special,” Nesbitt said. “There are many bones that get dug up, not all are immediately processed, prepared, and studied, No one had recognized the importance of this specimen before but we were able to borrow it and make our study.”

Researchers also found that this specific rauisuchid had two two close encounters with phytosaurs over its life. The findings shake up our understanding of Late Triassic ecosystems.

In their abstract, the authors write, “Previous distinctions between ‘aquatic’ and ‘terrestrial’ Late Triassic trophic structures were overly simplistic and built upon mistaken paleoecological assumptions; we show they were intimately connected at the highest trophic levels.

Stocker, along with colleagues, published their findings in the German journal Naturwissenschaften.

Image: teeth from a phytosaurs, The blue tooth is a 3-D printed replica of the tooth found embedded in the thigh bone of a rauisuchid.

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