Paleontologists have discovered a new species of extinct crocodile-like creature from fossilized remains found in southwest Montana, USA.
The newly identified species existed at the edge of the ancient western inland sea around 95 million years ago, during the late Cretaceous period.
It has been named Thikarisuchus Xenodentes, a type of neostian.
“Measurements indicate it was less than 60 cm (2 feet) from nose to tail tip,” stated David Barilisio, a professor at Montana State University. “If it had grown fully, it could have reached about 90 cm (3 feet) or more, but still much smaller than most members of the Neosuchia clade to which it belongs.”
“This clade includes modern crocodiles and their closest extinct relatives, most of which are semi-aquatic or marine carnivorous animals with simple cone-shaped teeth.”
In contrast, Thikarisuchus Xenodentes likely lived on land and possibly fed on plants, insects, and small animals, possessing a variety of tooth shapes.
“Its unique anatomy indicates it is part of a newly identified family of crocodile-like creatures endemic to the Cretaceous in North America.”
The fossilized remains of Thikarisuchus Xenodentes—including its limbs, vertebrae, jaw, and a skull measuring 50 mm—were discovered in the US Forest Service Black Reef Formation near Dillon, Montana, in the summer of 2021.
“We previously found dinosaurs in the Black Reef Formation, making this the second known vertebrate species discovered in this layer,” remarked Harrison Allen, a doctoral student at Stony Brook University.
Paleontologists found the bones of Thikarisuchus Xenodentes in a densely packed arrangement consistent with the fossils of other living creatures found in the dens of the Black Reef Formation and nearby Wayan Formation in Idaho.
“This supports the idea that Thikarisuchus Xenodentes was preserved in dens and that fossils from these layers are biased toward those found in such environments,” they noted.
The specimen also suggested connections to a newly established family group, wannchampsidae, and a related group identified in Eurasia, known as the Atopasauriaceae.
Both families were small, globally adaptive, and exhibited specific skull and dental characteristics shared with more distantly related groups from the Cretaceous period in Africa and South America.
“We propose that shared environmental conditions and prey availability led to convergent evolution between these two distantly related groups during the same timeframe.
“The vast majority of alligatorid diversity belongs to the past, including fully marine crocodiles, entirely terrestrial crocodiles, herbivorous, omnivorous species, and those with unique shells.”
“This discovery surprised me and motivated my interest in this specific field of paleontology.”
A paper detailing the findings is published in the Journal of Vertebrate Paleontology.
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Harrison Allen et al. 2025. The impact of newly discovered small heterodonneostians and heterodonneostians in southwestern Montana’s Black Leaf Formation on paleoecology. Journal of Vertebrate Paleontology in press; doi: 10.1080/02724634.025.2542185
Source: www.sci.news
