Taxonomic revision of a Machairodontinae (Felidae) from the Late Hemphillian of México.

In the Late Hemphillian of Guanajuato, México, fossil material assigned to Machairodus sp. cf. M. coloradensis (= Amphimachairodus coloradensis) was described in the 90´s. A detailed morphological reexamination of this material and its comparison to other felid genera raises doubts about its original taxonomic assignment. The presence of hypertrophied upper canine and almost all teeth with strong serration, confirms its identification as a Scimitar-tooth felid, but it is smaller than A. coloradensis. Because of the unique combination of synapomorphies present in this specimen, where a more developed flange stands out than another known Amphimachairodus, we propose that it represents a new taxon of felid and name a new species: A. alvarezi sp. nov. This new taxon adds information to the understanding of the diversity of machairodonts during the Miocene-Pleistocene times in North America. [ABSTRACT FROM AUTHOR]