Palynology of the Paleogene Cuayuca Formation (stratotype sections), southern Mexico: Chronostratigraphical and palaeoecological implications

Palynological markers such as Aglaoreidia pristina, Armeria, Bombacacidites, Corsinipollenites, Ephedripites claricristatus, Eucommia, Favitricolporites, Intratriporopollenites, Lymingtonia, Magnaperiporites, Malvacipollis spinulosa, Margocolporites vanwijhei, Momipites tenuipolus, Polyadopollenites aff. pflugii, and Thomsonipollis sabinetownensis recovered from the Cuayuca Formation permit it to be assigned a late Eocene–early Oligocene age. The evaporitic horizons of the Cuayuca Formation were deposited in a continental basin located south of Mexico City. The palynological assemblages indicate temperate-humid to dryer climates. The Cuayuca Formation was probably deposited in a shallow lacustrine basin under local xeric conditions with a semiarid climate that allowed the development of grassland (with Chenopodiaceae–Amaranthaceae, Gramineae, and Ephedra) and thorn shrub community (with Acacia, Leguminosae, Linum, and Plumbaginaceae). The neighboring communities were probably chaparral, tropical deciduous forest, low tropical deciduous forest, and thorn forest. In addition, there was regional temperate vegetation like Pinus forest and cloud forest.