FIGURE 1 in Eocene (Duchesnean and earliest Chadronian) brontotheres (Brontotheriidae), Protitanops curryi and cf. Parvicornus occidentalis, from West Texas and Mexico

FIGURE 1. Index map of collection areas (left) and correlation and dating (right) of the major mammal fossil localities of the Eocene of Trans-Pecos Texas. Magnetic stratigraphy of Testarmata and Gose (1979), Walton (1992), and Prothero (1996) and its correlation with the global magnetic polarity time scale. Location of the important mammalian local faunas (l.f.) and volcanic ash dates are shown. Diagonal cross-hachured pattern denotes sections of indeterminate polarity. Normal polarity is in black, reversed polarity is in white. Abbreviations: BRID. = Bridgerian; BR = Bracks Rhyolite; BU = Buckshot Ignimbrite; GB = Gill Breccia; MMR = Mitchell Mesa Rhyolite; MPTS = magnetic polarity; NALMA = North American land mammal age. (map after Wilson, 1978; correlation after Prothero, 1996).