Just out @ Journal of Mammalian Evolution
Following the Footsteps of the South American Equus: Are Autopodia Taxonomically Informative?
The genus Equus originated in the Pliocene Epoch of North America, and its arrival in South America is likely related to the Great American Biotic Interchange that took place in the transition of Pliocene to Pleistocene. Currently, there are five recognized species for the South American continent: Equus neogeus, E. santaeelenae, E. insulatus, E. andium, and E. lasallei. The taxonomy of the genus is traditionally based in part upon the proportions of the autopodia. The aim of this study is to evaluate the diagnostic importance of the autopodia of South American Equus through comparative and multiple statistical analyses. Therefore, we analyzed metacarpals, metatarsals, and phalanges from all available South American Equus, with the exception of E. lasallei, which is only known by a skull. We also examined the North American species E. occidentalis, as it has been interpreted to be closely related to South American Equus. Results showed no significant differences between the various South American species according to the dimensions and proportions of the autopodia. A continuum of gradual linear variation among the species was revealed, with superimposition between autopodial characters. The succession and overlap of species indicated that the South American Equus might represent a type of cline.
Keywords: Equus, Cline, Taxonomy, Autopodia
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