Recent collections of ammonites from rocks of Cenomanian and Turonian age in Trans-Pecos Texas and adjacent Chihuahua contain representatives of the families Schloenbachiidae, Acanthoceratidae, Vascoceratidae and Anisoceratidae. From these families 12 genera (one new: Quitmaniceras) and 15 species (7 new: Euhystrichoceras adkinsi, Pseudacompsoceras bifurcatum, Pseudaspidoceras flexuosum, Acanthoceras calvertense, Quitmaniceras reaseri, Q. brandi, Eucalycoceras underwoodi) are recorded herein from the Chispa Summit and Ojinaga formations.

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