Borealosuchus sternbergii

Overview

Borealosuchus sternbergii is a crocodyliform connecting North America at the end of the Cretaceous with the Paleocene. Its skull and parts of its body are known together. It is an animal encountered when comparing waterside scenes before and after the mass extinction of the dinosaurs.^[1][2]

Key facts

Another Borealosuchus species has also been found in the same area and strata. A 2022 Canadian study presented fossils of sternbergii and griffithi occurring together in the same strata. This raises questions about how similar crocodilian relatives divided food and space.^[2]

Time and place

This crocodilian relative of the latest Cretaceous and Paleocene is known from strata spanning about 72–63 million years ago. The first specimen studied came from present-day Wyoming, USA. Early Paleocene material from Saskatchewan, Canada, also broadens the story of its distribution.^[1][2]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

The rear of the head is broad, while the snout at the front is moderately broad and rounded. USNM6533 preserves material including jaws, eight vertebrae, and both humeri. The head outline can be compared together with the bones that supported the body.^[1]

Habitat and reproduction

The preservation of two species together in the same strata invites a fresh view of the lives of crocodilian relatives. Even along a single waterside, animals differing in size and bodily features can occupy their own places. Researchers examine such relationships through differences between fossils and the organisms found with them.^[2]

Fossil discovery

Gilmore described the specimen in 1910 under the name Leidyosuchus sternbergii. Later changes in classification led to the genus name Borealosuchus. New Canadian specimens in 2022 added evidence from a new place and time to the old name.^[1][2]

References

1. Gilmore (1910), “Leidyosuchus sternbergii, a new species of crocodile from the Ceratops beds of Wyoming,” Proceedings of the U.S. National Museum 38, no. 1762.
2. Lindblad et al.2022 — The Northern Crocodile from Saskatchewan’s lower Ravenscrag Formation
3. Gilmore (1910), “Leidyosuchus sternbergii, a new species of crocodile from the Ceratops beds of Wyoming,” Proceedings of the U.S. National Museum 38, no. 1762.
4. Lindblad et al.2022 — The Northern Crocodile from Saskatchewan’s lower Ravenscrag Formation
5. Buckley, G. A. & Brochu, C. A. (1999), “An enigmatic new crocodile from the Upper Cretaceous of Madagascar,” Special Papers in Palaeontology 60, pp. 149–175.
6. Turner, A. H. & Buckley, G. A. (2008), “Mahajangasuchus insignis (Crocodyliformes: Mesoeucrocodylia) Cranial Anatomy and New Data on the Origin of the Eusuchian-Style Palate,” Journal of Vertebrate Paleontology 28(2), 382–408.
7. Pochat-Cottilloux2025 — Non-semiaquatic adaptations of extinct crocodylomorphs

Research questions

Which crocodilian relatives survived and spread after a major extinction? Comparing old US specimens with Early Paleocene specimens from Canada allows us to follow that question. The coexistence of two similar species is also a clue to how ecosystems were reorganized.^[2]

Observation

Move your gaze from the rounded snout toward the broadened rear of the head.^[1]