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<\/a><\/p>\nAn artist\u2019s impression of Thikarisuchus xenodentes. Image credit: Dane Johnson \/ Museum of the Rockies.<\/p>\n
The newly-described species lived at the edge of the ancient Western Interior Seaway about 95 million years ago (Late Cretaceous epoch).<\/p>\n
Named Thikarisuchus xenodentes, the ancient creature was a type of neosuchian.<\/p>\n
\u201cMeasuring no more than 60 cm (2 feet) long from nose to tip of tail, this Thikarisuchus xenodentes individual was about the size of a big lizard,\u201d said Montana State University\u2019s Professor David Varricchio.<\/p>\n
\u201cHad it lived to be full grown, it would have measured no longer than 90 cm (3 feet), far smaller than most members of the Neosuchia clade to which it and its distant relatives belong.\u201d<\/p>\n
\u201cThe clade includes modern crocodilians and their closest extinct relatives, almost all of them semiaquatic or marine carnivores with simple, conical teeth.\u201d<\/p>\n
\u201cThikarisuchus xenodentes, 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.\u201d<\/p>\n
\u201cIts unique anatomy reveals that it was part of a new, previously unrecognized family of crocodyliforms endemic to the Cretaceous of North America.\u201d<\/p>\n
The fossilized bones of Thikarisuchus xenodentes \u2014 including its limbs, vertebrae, jaw and 50-mm-long skull \u2014 were found in the summer of 2021 in the Blackleaf Formation on U.S. Forest Service land near Dillon, Montana.<\/p>\n
\u201cWe have found dinosaurs in the Blackleaf Formation before, but this was the second known vertebrate animal we\u2019d ever found in this formation,\u201d said Harrison Allen, a doctoral student at Stony Brook University.<\/p>\n
The paleontologists discovered that the bones of Thikarisuchus xenodentes 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.<\/p>\n
\u201cThis suggests that Thikarisuchus xenodentes 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,\u201d they said.<\/p>\n
The specimens also presented clues about Thikarisuchus xenodentes\u2019 newly-named family group Wannchampsidae and a similar group found in Eurasia known as Atopasauridae.<\/p>\n
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.<\/p>\n
\u201cIt suggests that during the same time period, we\u2019re 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,\u201d Allen said.<\/p>\n
\u201cThe 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.\u201d<\/p>\n
\u201cThat amazed me and made me want to get into this more specific realm of paleontology.\u201d<\/p>\n