Evaluation of two historical collections of Louisiana vertebrate fossils housed in museum repositories revealed the presence of Paleogene shark and ray taxa that were heretofore unknown from the Gulf Coastal Plain of the USA. These include a new species of Carcharhinus, the sharks Isogomphodon sp., Mustelus sp., and Xiphodolamia ensis Leidy, 1877, and the ray Gymnura sp. Additionally, the first known lateral tooth of Eoplinthicus yazooensis Cappetta & Stringer, 2002 is described, improving our knowledge of the dentition of this extinct mobulid ray. The Isogomphodon sp. teeth represent the third fossil record of the genus from North America, whereas a single Mustelus sp. tooth is only the second Eocene record of this genus on the continent. One tooth of X. ensis provides the first record of the taxon in the Gulf Coastal Plain. The new Carcharhinus is distinct from all previously described Paleogene species, and it is the second Bartonian representative of the genus to be identified from deposits of the Eocene Mississippi Embayment. Two late Eocene Gymnura sp. teeth are the second Paleogene record of the genus in North America. These fossils improve our knowledge of Paleogene elasmobranch faunas on a local (Louisiana), regional (southeastern USA), and global scale.

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Cainozoic research

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David J. Cicimurri, & Jun A. Ebersole. (2021). New Paleogene elasmobranch (Chondrichthyes) records from
the Gulf Coastal Plain of the United States, including a new
species of Carcharhinus de Blainville, 1816. Cainozoic research, 21(2), 147–164.