A fossil the size of a pinkie tip has yielded a surprising discovery in croc evolution. A student-led team in Montana has identified a new species of crocodyliform-Thikarisuchus xenodentes-revealing unusual features and shifting assumptions about Cretaceous reptiles.

The fossil, nicknamed“Elton,” comes from the Blackleaf Formation in southwest Montana, in rocks dated to about 95 million years ago. Its discoverer, Harrison Allen-then an undergraduate-spotted an odd texture on a tiny bone fragment during a 2021 dig. That fragment later proved to be part of a remarkably well preserved juvenile skull and skeleton. The full description appears in a paper published this year in the Journal of Vertebrate Paleontology.

Elton would have measured about 60 cm from nose to tail as a juvenile; projections suggest a full-grown individual would reach no more than 90 cm, placing it among the smallest known crocodyliforms. While most neosuchians known from the period were semi-aquatic and equipped with simple conical teeth, Thikarisuchus presents a very different suite of traits.

One of the most striking features is its heterodont dentition: the specimen exhibits multiple tooth morphologies-conical, lanceolate, and rounded types-suggesting a more varied diet than typical carnivorous crocs. Researchers infer it likely consumed a mix of insects, plants, and small animals.

The distribution and arrangement of the bones also hint at preservation in a burrow environment-a pattern consistent with other fossils in the Blackleaf and neighbouring Wayan formations. This raises the possibility that much of the vertebrate fossil record in that region is biased toward burrowed organisms.

Phylogenetically, Thikarisuchus is placed in a newly defined clade, Wannchampsidae, alongside taxa such as Wannchampsus and an unnamed“Glen Rose form.” That clade is resolved as a sister-group to Atoposauridae, a lineage known chiefly from Europe, hinting at parallel evolution among small terrestrial croc relatives.

David Varricchio, a paleontology professor and co-author of the paper, emphasises the broader significance of the contribution. He notes that while modern crocodilians are relatively conservative in their morphology and ecology, their fossil predecessors occupied a far wider range of forms-including terrestrial, omnivorous, and even herbivorous roles. Elton expands that known diversity and challenges assumptions about the ecological constraints of crocodyliforms.

Allen, now a doctoral candidate, reflects that the find transformed his academic trajectory. What began as a student field project led him into digital reconstructions, advanced scanning work and in-depth phylogenetic analysis. The level of preservation allowed him to reconstruct nearly all skeletal regions-from limbs to vertebrae to the 50 mm skull-through CT scanning and meticulous segmentation.

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