Artistic reconstruction of Eosphorosuchus lacrimosa (left), bitten by a Hesperosuchus agilis (right), near a Coelophysis carcass. Credit: Julio Lacerda

Sometime around 210 million years ago, in what is now the badlands of New Mexico, a mudslide froze an ancient ecosystem in stone. Two swift, land-dwelling predators—about the size of modern jackals—perished side-by-side in a sudden catastrophic surge, leaving their skeletons locked in the earth as the world moved on.

Millions of years later, human hands dug up the now fossilized remains. For 75 years, these two skeletons sat in the basement of Yale’s Peabody Museum, assumed to belong to the same early crocodylomorph species.

But high-resolution CT scans have just revealed that at least one of the fossils belongs to an entirely new, short-snouted croc genus with a reinforced skull and a powerful bite. Researchers named the new species Eosphorosuchus lacrimosa. The new species suggests that long before crocodiles took to the water, their terrestrial relatives were already showing signs of ecological specialization and likely partitioning prey resources during the Triassic period.

Different ‘Jackal’ Crocs

Photographs and anatomical drawings of the skull of E. lacrimosa, viewed from the right/bottom (a, c) and the top/left (b, d). Credit: Miranda Margulis-Ohnuma

Paleontologists first pulled the massive blocks of rock from the Ghost Ranch bone bed in 1948. The site is known for its well-preserved fossils, being regarded as a sort of ancient graveyard of early dinosaurs, fish, and lizard relatives.

Researchers initially categorized the two predator skeletons buried there as Hesperosuchus agilis. At the time, early crocodile relatives were understood to be terrestrial, fast-running animals, unlike their semiaquatic relatives of today.

“During this period, the late Triassic, there were two reptile dynasties vying for dominance: the line that would produce crocodiles and alligators on one side, and that which would produce birds, which of course are dinosaurs, on the other,” Bhart-Anjan Bhullar, associate professor at Yale University and senior author of the study, said in a university press release.

“The dinosaurs at this time were slim, delicate animals that walked on two slender legs almost like herons, and the crocodiles were fast-running, four-legged predators, low-slung and more heavily built—analogous to a jackal, a big fox, or a dog.”

Yet something about the Yale museum specimen nagged at him.

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“I had been staring at this fossil for a while,” Bhullar noted. “For years, both Ghost Ranch crocs were thought to be examples of Hesperosuchus, but it looked like the Yale animal had a different facial structure.”

The Dawn Bringer of Ghost Ranch

Line drawings and extracted renderings of the skull of Eosphorosuchus lacrimosa in right lateral view (a) and dorsal view (b), the posterior lower jaw in
lateral view (c) and the palate in ventral view (d). Credit: Miranda Margulis-Ohnuma

To test that hunch, the Yale team needed to peer inside the solid rock without destroying the delicate fossils. Miranda Margulis-Ohnuma, a Ph.D. student and the study’s lead author, turned to a powerful CT scanner. Slicing through the stone with continuous X-rays, she digitally “disassembled” the crushed skeleton bone by bone. The hidden anatomy confirmed their suspicions: this was a creature vastly different from its long-snouted companion.

The team named the new animal Eosphorosuchus lacrimosa. The genus name combines the Greek words “Eosphorus,” the dawn-bringer, with “soukhos,” crocodile, while “lacrimosa” highlights the animal’s distinctive lacrimal skull bone near its eyes. The authors specifically tie the name Eosphoros as a counterpart to Hesperos—H. agilis meaning the ‘Dusk crocodile’.

“Eosphorosuchus is one of only a handful of well-preserved early crocodile relatives, and its coexistence with Hesperosuchus represents the ‘dawn’ of functional diversification in the lineage that would give rise to modern crocodiles,” Margulis-Ohnuma said in the Yale statement.

The scans uncovered a remarkably short snout and a reinforced skull. The animal featured a large, triangular postorbital bone behind the eye and a prominent ridge on its lower jaw. In life, these thick bones anchored massive jaw muscles—specifically the adductor mandibulae externus superficialis—suggesting the predator had a powerful bite force.

The creature’s fossilized foot even bore a healed wound containing an embedded tooth fragment, hinting at a violent encounter earlier in its life.

Triassic Coexistence

Left hindlimb of E. lacrimosa: pelvis (a), leg bones (b), ankle (c), and foot (d). Credit: Miranda Margulis-Ohnuma

The sheer physical power of E. lacrimosa suggests it may have been adapted to tackle relatively larger or less agile prey. Just about 5 meters away (15 feet) lay the remains of H. agilis, which likely used its longer snout to snap up smaller, more agile targets. Finding two distinct predators in the same muddy grave suggests that these early crocodile cousins were already splitting up the food web, specializing to avoid direct competition.

“It’s a time-slice of a single moment 210 million years ago,” Bhullar stated. “These two individuals had to compete and interact with each other. They were quite possibly looking at each other when they died.”

Such discoveries are incredibly rare. The early branches of the crocodile family tree remain sparsely populated in the fossil record, leaving researchers hungry for more data.

“This is the first really strong evidence we have of coexistence between two functionally different-looking crocodylomorphs,” Margulis-Ohnuma told Live Science. “For early crocs, we’re very data deficient, so every new fossil that comes out is changing the story. If we can continue to describe this material that we have, and ideally find new fossils, it will change the story every single time.”

The paper was published in the journal Proceedings of the Royal Society B: Biological Sciences.