Biology:Leidyosuchus
Leidyosuchus (meaning "Leidy's crocodile") is an extinct genus of eusuchian, either an alligatoroid crocodilian or a stem-group crocodilian, from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis.[1] It is known from a number of specimens from the middle Campanian age Dinosaur Park Formation. It was a medium-sized alligatoroid, with a maximum skull length greater than 40 centimeters (16 in).[2]
A number of species had been assigned to this genus over the years, including: L. acutidentatus (Sternberg, 1932), from the Paleocene of Saskatchewan; L. formidabilis (Erickson, 1976), from the Paleocene of North Dakota and Wyoming; L. gilmorei (Mook, 1942), from the Campanian of Alberta; L. multidentatus (Mook, 1930); L. riggsi (Schmidt, 1938); L. sternbergii (Gilmore, 1910), from the Maastrichtian (Late Cretaceous) of Colorado, Montana, North Dakota, South Dakota, and Wyoming; and L. wilsoni (Mook, 1959), from the Eocene of Wyoming.[2] However, in 1997 Chris Brochu reevaluated the genus and reassigned most of the species, transferring L. acutidentatus, L. formidabilis, L. sternbergii, and L. wilsoni to the new genus Borealosuchus, and L. multidentatus to the new genus Listrognathosuchus, proposing L. gilmorei as a synonym of L. canadensis, and finding L. riggsi to be too fragmentary to be determinable.[2][3]
Classification
Leidyosuchus is one of the basal-most members of the superfamily Alligatoroidea. Leidyosuchus's placement within Alligatoroidea can be shown in the cladogram below, based on a 2018 tip dating study by Lee & Yates that simultaneously used morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data.[4]
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In a 2025 study, however, Jules D. Walter and colleagues argue that many character states previously thought to be diagnostic for alligatoroids were actually much more widespread. In their analysis several genera traditionally viewed as basal alligatoroids, among them Leidyosuchus, were found to not only fall outside of Alligatoroidea but to not even be true crocodilians, instead representing derived non-crocodilian eusuchians. Leidyosuchus was recovered as having split from the lineage leading up to Crocodilia before Deinosuchus and the terrestrial Planocraniidae.[5]
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References
- ↑ Lambe, Lawrence M. (1907). "On a new crocodilian genus and species from the Judith River Formation of Alberta". Transactions of the Royal Society of Canada. Series 3 1 (4): 219–235.
- ↑ 2.0 2.1 2.2 Wu, Xiao-Chun (2005). "Crocodylians". in Currie, Philip J.. Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 277–291. ISBN 0-253-34595-2. https://archive.org/details/dinosaurprovinci0000unse/page/277.
- ↑ 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. doi:10.1080/02724634.1997.10011017.
- ↑ Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B 285 (1881). doi:10.1098/rspb.2018.1071. PMID 30051855.
- ↑ Walter, J. D.; Massonne, T.; Paiva, A. L. S.; Martin, J. E.; Delfino, M.; Rabi, M. (2025). "Expanded phylogeny elucidates Deinosuchus relationships, crocodylian osmoregulation and body-size evolution". Communications Biology 8: 611. doi:10.1038/s42003-025-07653-4.
Template:Extinct Crocodilia
Wikidata ☰ Q2366128 entry
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