By Steven Scarpa
Yale Peabody Museum Ph.D. students Miranda Margulis-Ohnuma ‘25 and Alexander Ruebenstahl, working with curator Bhart-Anjan Bhullar ‘05, have identified a proto-crocodile predator whose strong bite sets it apart from similar animals and offers a new understanding of the evolution of modern alligators and crocodiles.
This nimble creature about the size of a beagle, named Eosphorosuchus lacrimosa, lived over 200 million years ago and offers paleontologists insights into how vertebrate animals evolved while living on land. “Eosphorosuchus captures an intermediate stage between modern crocodiles and alligators and their common ancestor with birds,” Bhullar said. “It’s a beautifully preserved fossil.”
The research recently appeared in the journal Proceedings of the Royal Society B. Recent Yale Peabody Ph.D. graduate Dalton Meyer ‘25 PhD was a coauthor.
The name was carefully selected to allude to the creature’s role in evolution, pulling from Greek mythology and language for the moniker. “As Eosphoros was the ‘dawn-bringer,’ this name highlights both the dawning of crocodylomorph ecological diversity and the close historic association of this specimen with the genus Hesperosuchus,” according to the paper.
Eosphorosuchus came to light thanks to an extraordinary, Pompeii-like incident. A cataclysmic event in the Late Triassic period, perhaps a flood, killed dozens of creatures around a riverbank in Ghost Ranch, New Mexico and allowed everything nearby to be buried together. Finding fossils from the same time in the very same location is rare, Bhullar explained.
“These animals were together at the same moment on the same day. It’s among our best snapshots of a scene in an antediluvian world that’s both alien and bizarre and paradoxically the same place we are standing right now,” Bhullar said.
That rock bed was unearthed during a 1948 expedition led by researchers from the American Museum of Natural History and parts were delivered to the important paleontological research institutions of the time, including the Yale Peabody Museum and Harvard University, among others.
The crocs found in the bone bed were thought to be examples of Hesperosuchus, a well-documented species. The materials sat, unexplored, for over five decades, until Bhullar and colleagues decided to take a freshlook. They noticed something unexpected, a crocodile with a different anatomical structure.
“It was obvious that this thing was something new. The skull looked different. I’d seen enough of these things to notice that this one looked chunky, almost bulldog like compared to the others,” he said. “It was a heavily built, short-faced thing.”
That fresh look would prove to be vital. A few years ago, Margulis-Ohnuma became interested in delving further. She completed a computed tomography (CT) scan of the crocodile, allowing her to digitally dissect the bones without touching the fossil. It also allowed her to reassemble the bones that had been jostled apart, giving a sense of the animal’s anatomy.
“We can analyze the anatomy both for its relationships and how it fits into the first flowering of the crocodile line. Its unique anatomical features will tell you something about how it lived and how it fit into this vanished ecosystem,” Bhullar said.
Her analysis showed that Bhullar’s initial impression was right. Highly developed musculature around the jaws indicated that the creature had a strong bite, he said. The ancestors of modern crocodiles and alligators were not fat and amphibious the way that modern ones are. They ran around on land much like wolves and jackals, Bhullar said.
“It’s a crocodile cousin, among the closest known extinct relatives to living crocodiles and alligators. When the lineage split, the bird line became lightweight and slender and developed elaborate breathing systems. The other line, what would become crocodiles and alligators, became heavy bruisers,” he said.
One of the goals of the work is to connect the past with what we see in nature today. Bhullar’s lab couples technology to concepts of modern biology, breathing life into ancient skeletal structures. The reality of how ancient animals actually lived is never far away. “When I look at a bone, I don’t see a standalone element, but a connective tissue structure that has grown in the interstices among the more active parts of the body,” he said.
Because of that, Bhullar can infer a great deal about the life of these long-lost animals. “You can understand the parts that make an animal move, think, hear, see, and feel,” he said.