Museum Fossil Reveals Triassic Crocodile Cousin with Powerful Jaws

CT scans of a decades-old specimen from the Yale Peabody Museum of Natural History show a new species of crocodylomorph with a short snout and unusually strong jaws, providing a rare snapshot of ecological specialization during the Late Triassic period.

Eosphorosuchus lacrimosa (left) is disturbed by Hesperosuchus agilis (right) near a Coelophysis carcass in what will become present-day Ghost Ranch, New Mexico, United States. Image credit: Julio Lacerda.

Eosphorosuchus lacrimosa lived 210 million years ago near the rivers and lakes of what is now New Mexico, United States.

This reptile was a fast predator with large hind legs and smaller, thinner arms.

It also had a short snout, a heavily reinforced skull, and well-developed jaw muscles, perfect for closing down on large prey.

“This speaks to the diversification of proto-fangs around the beginning of the Reptile Age,” said Dr. Bhart-Anjan Bhullar, a paleontologist at Yale University and the Yale Peabody Museum of Natural History.

“During this period, the Late Triassic, there were two reptile dynasties vying for dominance: the lineage that would produce crocodiles and alligators on one side, and the one that would produce birds, which are of course dinosaurs, on the other.”

“Dinosaurs of this era were thin, delicate animals that walked on two thin legs almost like herons, and crocodiles were fast, four-legged, low, more heavily built predators – analogous to a jackal, a large fox or a dog.”

The holotype specimen of Eosphorosuchus lacrimosa includes parts of the skull, lower jaw, vertebrae, limbs and armor elements.

Excavated in 1948 at Ghost Ranch in New Mexico, the fossil has been known to science for three-quarters of a century, but it has never been fully examined or identified.

The team’s phylogenetic analysis locations Eosphorosuchus lacrimosa near the base of Crocodylomorpha, outside a clade that includes another small crocodylomorph called Hesperosuchus agilis.

This indicates that its distinctive features evolved early in crocodylomorph history.

It is important to note that the fossilized remains of Eosphorosuchus lacrimosa were found in the same assemblage as Hesperosuchus agilis.

The coexistence of these two forms suggests that early crocodylomorphs already shared ecological niches, even among terrestrial predators of similar size.

“Eosphorosuchus lacrimosa is one of the few well-preserved ancient crocodile relatives, and its coexistence with Hesperosuchus agilis represents the ‘dawn’ of functional diversification in the lineage that would give rise to modern crocodiles,” said Miranda Margulis-Ohnuma, a doctoral student at Yale University.

“In addition to its unique anatomy and conservation history, the specimen demonstrates the potential of existing museum collections to continue to reveal new insights into the history of life.”

“What makes this discovery particularly interesting,” the researchers say, “is the fact that it provides a snapshot of an ancient ecosystem whose biodiversity was rich enough for its close relatives to share their ecological roles by specializing their dietary anatomy.”

The team’s paper was published this month in the Proceedings of the Royal Society B.

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Miranda Margulis-Ohnuma and others. 2026. A short-snouted “sphenosuchian” with unusual dietary anatomy demonstrates that ecological specialization occurred early in crocodylomorph evolution. Proc Biol Sci 293 (2069): 20260130; doi: 10.1098/rspb.2026.0130