The Plio-Pleistocene cheetah-like cat Miracinonyx inexpectatus of North America


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Journal of Vertebrate Paleontology

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The taxonomy of the North American cheetah-like cats is unresolved as they have been assigned at different times to Felis, Puma, or Acinonyx. A recently discovered, nearly complete skeleton of a large, slender-limbed cat of Irvingtonian age from West Virginia prompted this study of their relationships. We describe the new specimen and compare it with the living puma (Puma concolor) and cheetah (Acinonyx jubatus) as well as with the extinct Old World cheetah (A. pardinensis) and New World cheetah-like cats most recently assigned to Acinonyx trumani and A. studeri. The new specimen appears to be a member of the earlier of the two North American species, previously known as A. studeri, here called Miracinonyx inexpectatus based on the priority of Cope's (1895) name. A cladistic analysis suggests that the New and Old World forms are distinct at the generic level and we remove the North American taxa from Acinonyx and place them in the genus Miracinonyx. The two genera are distinguished by a minimum of ten features of the skull and postcranial skeleton. Miracinonyx differs from Puma primarily in limb proportions, slenderness of the long bones, and aspects of the nasomaxillary region of the skull. A review of the fossil record suggests that the extinction of M. inexpectatus preceded the appearance of both the cursorial M. trumani and the shorter-limbed Puma concolor. Thus, M. inexpectatus could have given rise to both of these taxa in the middle Pleistocene.

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