Triassic croc relative from Ghost Ranch, New Mexico finally identified after nearly 80 years in museum basement

During the Triassic around 205 million years ago, a newly-identified relative of modern crocodiles stalked its prey, but not in the water, a new study finds.

Like other ancient crocodile cousins, this newly identified species hadn't yet ventured into the water. Instead, it hunted its prey on land, much like a modern fox or jackal, the researchers said.

It would have been a fearsome predator, with its fossil suggesting "specialization for a powerful bite," the researchers wrote in the study.

The specimen was originally discovered decades ago, in 1948 at Ghost Ranch, New Mexico, in a well known dinosaur death bed. At the time, it was tentatively cataloged as a specimen of Hesperosuchus agilis, a small, early relative of crocodiles and alligators. But now, the new study shows that the creature's unusually short snout and thick, reinforced skull set it apart as an entirely new genus and species, though the creature lived — and died — at the same time and place as H. agilis.

"This is the first really strong evidence we have of coexistence between two functionally different-looking crocodylomorphs," study co-author Miranda Margulis-Ohnuma, a paleontologist at Yale University, told Live Science. Crocodylomorphs include modern crocodiles, alligators, caimans and their extinct relatives.

The fossil of the short-snouted creature, newly dubbed Eosphorosuchus lacrimosa, was uncovered in a Late Triassic (237 million to 201 million years ago) formation. The animal's skull, the bones of one of its back legs, one vertebra, and three scales were preserved. The creature would have been about the size of a large dog.

"It was in the basement of the Peabody Museum [at Yale] for, literally, 75 years," Margulis-Ohnuma said. "People would sometimes come visit and look at it, but it had never been identified."

In the new study, published Wednesday (April 15) in the journal Proceedings of the Royal Society B: Biological Sciences, Margulis-Ohnuma and her colleagues categorized the fossil in detail and compared it with a fossil of H. agilis found about 15 feet (5 meters) away. The animals in this section of Ghost Ranch lived at the same time, and they died and were buried in a single event, possibly a flood.

E. lacromisa has a much shorter snout than H. agilis, the team found. It also has a larger, triangular postorbital — a bone in the skull — and matching features on its lower jaw that may have accommodated strong muscles for chomping. Together, those traits suggest the creature had a very powerful bite.

Because E. lacrimosa and H. agilis lived alongside each other, the team suspects they occupied different ecological niches. For example, crocodilians with shorter snouts may have fed on larger, less-agile prey than species with longer snouts did.

"It's really cool that it's not a lineage that's just struggling to take off — at this point, there's already diversity," Margulis-Ohnuma said. "We're really getting a snapshot of the very beginning of functional diversity across crocs."

Scientists don't know much about the early stages of crocodylomorph evolution. There aren't many of these animals preserved in the fossil record, Margulis-Ohnuma said, and many crocodylomorph species from the Triassic are represented by a single fossil specimen.

"For early crocs, we're very data deficient, so every new fossil that comes out is changing the story," Margulis-Ohnuma told Live Science. "If we can continue to describe this material that we have, and ideally find new fossils, it will change the story every single time."