FIVE DECADES OF COMPLEMENTARY VERTEBRATE PALEONTOLOGY AND RADIO-ISOTOPIC GEOCHRONOLOGY RESEARCH IN MEXICO: RESULTS AND PERSPECTIVES
The late J.W. Wilson and the senior author, then his student, started this effort in the late 60’s, dating the potentially mammal-bearing, Yanhuitlán Formation [Southeastern Mexico = SEM], which much later yielded the southernmost Eocene fauna of North America. The systematic endeavor to date Tertiary mammal-bearing units was pioneered too by the senior author, with the cooperation of F. McDowell [Univ. Texas], thus dating Miocene sequences/faunas [= s/f] in Oaxaca and Chiapas [SEM]. A parallel endeavor to date Late Miocene-Pliocene s/f from basins across the Trans-Mexican Volcanic Belt [= TMVB] was developed by O. Carranza [former student] and his associates from Utah.
Other efforts to date s/f gave these data: one Late Pliensbachian [Sierra Madre Oriental = SMO], one Late Campanian [Peninsula de Baja California], one early Eocene [Central Plateau = CP], one Late Miocene [SMO], and ~20 Pleistocene scattered across the country [Northwestern Plains and Sierras, CP, TMVB (most), Sierras Madres del Sur and de Chiapas]. The results of the s/f datings have improved understanding of tectonic evolution [e.g. central-eastern Pangea (Jurassic), Baja California (Cretaceous), north-central Mexico (Laramide Orogeny), SEM (Eocene-Miocene)], of key paleobiotic events [e.g. Great American Biotic Interchange, Cenozoic evolution of the mammal fauna in southern North America]; and the Pleistocene/Holocene environmental change. Yet, much has to be done on these and other subjects e.g intensive s/f dating in other morphotectonic provinces, Pleistocene dating outside the TMVB, humans-direct dating.