Today, we're going talk about another crocodylian from Hell Creek - Borealosuchus sternbergii!
Borealosuchus sternbergii model, WIP.
Borealosuchus sternbergii was originally assigned to the genus Leidyosuchus, but a reevaluation of that genus led to the formation of the new genus Borealosuchus, to which B. sternbergii was assigned - it is now the type species for the genus Borealosuchus (Brochu, 1997).
A paper in 2012 placed Borealosuchus as the most basal member of the genus. The exact relationships between Borealosuchus and the rest of crocodylia is not fully resolved - many phylogenic analyses placed the genus closer to Brevirostres (alligators and crocodiles) than to Gavialoidea (gharials) (Brochu et al., 2012), several placed it closer to Gavialoidea than to Brevirostres (Puértolas et al., 2011), and a few placed it outside of Crocodylia entirely (Pol et al., 2009). However, the authors note that all three are equally parsimonious (Brochu et al., 2012), so only further research will be able to resolve this issue.
Unfortunately, there is not much for me to write about Borealosuchus paleobiology or paleoecology, as most of the research that involves the genus is about its relationships to other crocodylians rather than the actual lifestyle of the animal. However, based on my own knowledge of crocodylians and modern ecosystems I have a few ideas about how it may have lived. Keep in mind that this is purely speculative and should be taken with a grain of salt.
While Borealosuchus does not have resolved relationships to other crocodylians, its cranial anatomy appears similar to that of modern crocodiles. This, combined with the fact that the Hell Creek formation was bordered by the shrinking Western Interior Seaway, makes me think that it may have lived similarly to the modern American crocodile (Crocodylius acutus). In the Everglades, American crocodiles and American alligators are separated for the most part by habitat preference - they tend to be closer to the coast, in more salty bodies of water such as brackish lakes, mangroves, lagoons, etc. Alligators, on the other hand, prefer more inland, fresh water. It could be that Borealosuchus shared this preference, with Brachychampsa dominating in the more inland bodies of water. In fact, the original material from which B. sternbergii was described came from the Lance formation (Gilmore, 1910), which was a coastal floodplain environment - this may be supportive of my hypothesis.
Well, I hope this has given you a bit more information about Borealosuchus sternbergii! I know it was a bit short, but I did what I could with what I could find.
Unfortunately, there is not much for me to write about Borealosuchus paleobiology or paleoecology, as most of the research that involves the genus is about its relationships to other crocodylians rather than the actual lifestyle of the animal. However, based on my own knowledge of crocodylians and modern ecosystems I have a few ideas about how it may have lived. Keep in mind that this is purely speculative and should be taken with a grain of salt.
While Borealosuchus does not have resolved relationships to other crocodylians, its cranial anatomy appears similar to that of modern crocodiles. This, combined with the fact that the Hell Creek formation was bordered by the shrinking Western Interior Seaway, makes me think that it may have lived similarly to the modern American crocodile (Crocodylius acutus). In the Everglades, American crocodiles and American alligators are separated for the most part by habitat preference - they tend to be closer to the coast, in more salty bodies of water such as brackish lakes, mangroves, lagoons, etc. Alligators, on the other hand, prefer more inland, fresh water. It could be that Borealosuchus shared this preference, with Brachychampsa dominating in the more inland bodies of water. In fact, the original material from which B. sternbergii was described came from the Lance formation (Gilmore, 1910), which was a coastal floodplain environment - this may be supportive of my hypothesis.
Well, I hope this has given you a bit more information about Borealosuchus sternbergii! I know it was a bit short, but I did what I could with what I could find.
Acknowledgements:
Brochu, C. A. 1997. A review of "Leidyosuchus" (Crocodyliformes, Eusuchia) from the Cretaceous through Eocene of North America. Journal of Vertebrate Paleontology 17 (4): 679-697.
Brochu, C. A.; Parris, D. C.; Grandstaff, B. S.; Denton, R. K. Jr.; Gallagher, W. B. 2012. A new species of Borealosuchus (Crocodyliformes, Eusuchia) from the Late Cretaceous-early Paleogene of New Jersey. Journal of Vertebrate Paleontology 32 (1): 105-116.
Puértolas, Eduardo; Canudo, José I.; Cruzado-Caballero, Penélope. 2011. A New Crocodylian from the Late Maastrichtian of Spain: Implications for the Initial Radiation of Crocodyloids. PLoS ONE 6 (6) e20011.
Pol, Diego; Turner, Alan H.; Norell, Mark A. 2009. Morphology of the late Cretaceous crocodylomorph Shamosuchus djadochtaensis and a discussion of neosuchian phylogeny as related to the origin of Eusuchia. Bulletin of the American Museum of Natural History 324: 1-103.
Gilmore, C. W. 1910. Leidyosuchus sternbergii, a new species of crocodile from the Cretaceous Beds of Wyoming. Proceedings of the United
States National Museum 38(1762): 485-502.
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