About 95 million years ago, a juvenile crocodyliform nicknamed Elton lived in what is now southwest Montana at the edge of the Western Interior Seaway.

Measuring no more than 2 feet long from nose to tip of tail, young Elton was about the size of a big lizard, according to Montana State University professor of paleontology David Varricchio. Had it lived to be full grown, Elton would have measured no longer than 3 feet, far smaller than most members of the Neosuchia clade to which it and its distant relatives belong.

The clade includes modern crocodilians and their closest extinct relatives, almost all of them semiaquatic or marine carnivores with simple, conical teeth.

Elton, by contrast, lived on the land, probably feasting on both plants and insects or small animals with its assortment of differently shaped and specialized teeth. Its unique anatomy reveals that it was part of a new, previously unrecognized family of crocodyliforms endemic to the Cretaceous of North America.

If not for the sharp eye of Harrison Allen, a 2023 graduate of MSU’s Department of Earth Sciences in the College of Letters and Science, Elton’s ancient remains may never have been discovered. But during a dig in the summer of 2021 in the Blackleaf geological formation on U.S. Forest Service land near Dillon, Allen—then a student in Varricchio’s field paleontology course—noticed a fossil the size of the tip of his pinkie with a “weird texture on it.”

“I brought it to Dr. Varricchio and knew it must be something good, because he said, ‘Take me to where you found this,’” said Allen, who is now studying croc paleontology as a doctoral student at Stony Brook University in New York.

It was an exciting moment for Allen, originally from Kentucky, who chose MSU because it offers a paleontology track for undergraduates majoring in earth sciences.

Four years and hundreds of hours of study later, he is the lead author of a paper published in the Journal of Vertebrate Paleontology that describes the morphology and scientific significance of the creature whose remains he found in the Blackleaf Formation.

“After the dig, Dr. Varricchio told me why he was so excited the day I found the initial specimen. It had so much visible anatomy to explore, and he could see it was a tiny, tiny croc skull, fully articulated and preserved—it was a special thing,” Allen said.

“We have found dinosaurs (in the Blackleaf) before, but this was the second known vertebrate animal we’d ever found in this formation.”

The extinct animal, which Allen and the paper’s co-authors later named Thikarisuchus xenodentes for its strange, sheathed teeth, has provided new information about the paleoecology of the Blackleaf ecosystem and about patterns of evolution in the croc family tree.

It also provided the ultimate undergraduate research project for Allen, who delved into the painstaking process of excavating, sifting and reconstructing the Thikarisuchus remains with the help of some fellow students.

“As an undergraduate student new to research, I nervously went up to Dr. Varricchio and asked if I could study this specimen,” Allen said. “It led me down the rabbit hole into this amazing world of prehistoric, extinct crocs and their evolutionary niches.”

The day after Allen recovered the first piece of skeleton, he and his classmates scooped up several bags of sediment from the mound where it was found.

Back in Bozeman, Allen and his friend Dane Johnson, who graduated in 2022 and is now a paleontology lab and field specialist at MSU’s Museum of the Rockies, spent between 10 and 20 hours sifting out fine particulate matter and dirt, eventually recovering dozens of tiny pieces of the Thikarisuchus skeleton that collectively fit into the palm of Allen’s hand.

As they worked, they listened to music, including Elton John’s 1970s hit “Crocodile Rock.” The nickname “Elton” stuck, long before the specimen was assigned the scientific name that reflects its physical traits.

Allen and Johnson recovered bits of bone from almost all areas of the animal’s body, including its limbs, vertebrae, jaw and 50-millimeter-long skull. Because the fragments were tiny and exceptionally fragile, the students didn’t attempt to physically reassemble them.

Instead, they took them for a series of CT scans, including some at MSU’s Subzero Research Laboratory. Allen estimates that he spent well over 100 hours coloring the digital, 2D segment slices that the scans produced, a process necessary to visually distinguish the bones from the rocks they were embedded in.

“Harrison worked super hard to digitally reconstruct the animal, and it came out beautifully,” said Varricchio.

During the process, Allen discovered that the bones of Thikarisuchus were densely concentrated and organized in a manner consistent with fossils of organisms found in burrows in the Blackleaf Formation and the nearby Wayan Formation in Idaho.

He said this suggests that Thikarisuchus was likewise preserved within a burrow, further supporting the notion that fossils recovered from these formations are biased toward those that were preserved in burrows.

The specimen also presented clues about Thikarisuchus’ newly named family group Wannchampsidae and a similar group found in Eurasia known as Atopasauridae.

Both groups were tiny and terrestrially adapted, and they shared certain cranial and dental features found in another more distantly related group from the Cretaceous of Africa and South America.

“It suggests that during the same time period, we’re seeing convergent evolution between two distantly related groups due to similar environmental conditions, prey availability and who-knows-what that prompted crocs on opposite sides of the planet to develop similar features,” Allen said.

As he works toward his Ph.D. and a career as a paleontology professor, Allen said his experiences with Elton cemented his research interest, which has since broadened to include extinct crocs from all over the world.

“The majority of diversity of crocodyliforms is in the past. There were fully marine crocs, fully terrestrial crocs, herbivorous crocs, omnivores and some that cracked shells,” he said. “That amazed me and made me want to get into this more specific realm of paleontology.”

Varricchio said he feels fortunate that students like Allen choose to study at MSU.

“It was a true pleasure to have Harrison as a student here—so much positive enthusiasm, followed up with great research,” he said.