Pleistocene mammals of Mexico: A critical review of regional chronofaunas, climate change response and biogeographic provinciality

Mexico's Pleistocene terrestrial mammal record includes 13 orders, 44 families, 147 genera and 280 species, thus is comparable to the Recent one, but shows greater ordinal and family diversity. Post-Pleistocene extinction chiefly involved meso- and megabaric species. The mammal, palynologic and paleosol records are strongly time and space biased in favor of Late Rancholabrean data from a few morphotectonic provinces; hence, only broad climatic trends could be delineated, which approximately coincide with those known for the Wisconsinan; they disclose by 25-12 ka, greater moisture and cooler temperature conditions than at present, coinciding too with a larger mammalian diversity and local faunas disharmony. Climate fluctuations impacted the fauna, causing species distribution changes and extinctions. The Recent fauna's complex biogeographic pattern reflects this; it includes tropical and temperate species associations outside their respective latitudes. Combining geologic and Recent mammal distribution data with the Pleistocene record, possible dispersal routes were detected: high and low land, southward corridors for temperate species, and low land, northward ones for tropical species. Finally, the existence of a single Mexican Rancholabrean Faunal Province is incompatible with mammal record's makeup and distribution, which calls for a multiprovince scheme to better understand Mexico's Pleistocene mammal biogeography and faunistics.