Boasting an Unusual Set of Teeth, This Extinct Crocodilian Ate Dinosaurs and Plants
Burrowed underground in southwest Montana, the skeletal remains of an ancient crocodilian creature have built a new branch of a Cretaceous-era family tree. This croc — nicknamed “Elton” — only grew to around 2 feet long by the time it died around 95 million years ago.
A study recently published in the Journal of Vertebrate Paleontology shows how Elton’s discovery has bridged the gap between long-lost relatives of modern crocodiles. The extinct crocodyliform has now been adopted into a newly-established family group, and its unique set of teeth has revealed ties to similar species that lived during the Cretaceous period — even some all the way over in Eurasia.
Read More: As Masters of Survival and Evolution, the Crocodile Now Has Two New Species
A Rockin’ Crocodilian
Elton was first discovered in 2021, when Harrison Allen, an undergraduate student at Montana State University at the time, came across a fossil the size of a pinky tip at Montana’s Blackleaf geological formation. This prompted more digging, leading researchers to unearth dozens of fossilized skeleton fragments that needed to be sifted out from sediment. Eventually, all the pieces of this skeletal puzzle fell into place — the researchers figured out that they belonged to a small juvenile crocodyliform.
“We have found dinosaurs (in the Blackleaf) before, but this was the second known vertebrate animal we’d ever found in this formation,” said Allen, who is the lead author of the new study.
Elton’s name probably rings a bell. That’s because it was initially named after singer Elton John — while researchers were sifting through sediment, they cranked up a few tunes, including Elton John’s 1972 hit “Crocodile Rock.” The nickname, according to a press release on the study, simply stuck.
The researchers, however, later came up with a scientific name for Elton that’s not quite as musical: Thikarisuchus xenodentes. It was given this name because of its strange, sheathed teeth, one of the focal points out in the study.
Bringing the Family Together
Since the skeletal fragments were so tiny and fragile, researchers had to use a series of CT scans to piece the specimen together. Overall, they found bones from almost all areas of the animal’s body, including its limbs, vertebrae, jaw, and 50-millimeter-long skull.
The researchers also noticed similarities between Thikarisuchus and two other members of the Neosuchia clade (which includes all modern crocodilians and their extinct close relatives): Wannchampsus kirpachi and an undescribed specimen known as the “Glen Rose Form” (or USNM 22039). This inspired them to propose a new clade incorporating all three, which they call Wannchampsidae.
Exploring this family group even further, the researchers determined that it is closely related to another extinct group found in Eurasia, Atoposauridae. Both of these groups were tiny and terrestrially adapted, a rarity among neosuchian species (most of which have been aquatic or semi-aquatic). The two groups also shared certain cranial and dental features found in another, more distantly related group from Cretaceous-era 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.
The Versatile Teeth of Thikarisuchus
Based on its bones, the researchers deduced that Thikarisuchus was preserved within a burrow, similar to other fossils of organisms in the Blackleaf Formation.
Thikarisuchus and the two other wannchampsids also stand out because they had heterodont dentition, meaning they had teeth with more than one shape to fulfill different purposes. They would’ve had some teeth that helped them catch smaller mammalian or dinosaur prey, and others meant to slice or chop plant material or insects. The researchers therefore suggest that the diet in wannchampsids likely ranged from omnivore to insectivore.
The discovery of Elton has made one thing clear: Crocodilians of the past were extremely diverse. Some were fully marine, while others were fully terrestrial. Some were herbivores, while others were omnivores. Even with a new family group in the picture, there’s still much to learn about ancient crocodyliforms and their assorted features.
Read More: At 12 Feet and 550 Pounds, This Crocodile Relative Devoured Dinosaurs Around 70 Million Years Ago
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