Insect fossil evidence of late glacial and Holocene environments in the Bolson de Mapimi, Chihuahuan Desert, Mexico; comparisons with the paleobotanical record

Abstract

This paper discusses fossil insect studies from the Bolson de Mapimi region in the southern Chihuahuan Desert of Mexico. Fossil packrat middens from three study areas were analyzed, providing paleoenvironmental reconstructions of late Wisconsin to late Holocene age. Paleofloristic analyses of late Wisconsin samples from two of the three areas have been published; the insect results are in good agreement with the paleobotany. The late glacial assemblages comprise a mixture of temperate and desert taxa, in addition to some tropical and subtropical elements. In contrast to faunas from other Chihuahuan Desert regions, only one temperate species was found in the late glacial assemblages. Following a temporal hiatus (12,000-9000 yr BP), most of the late glacial fauna disappears from the records. Desertscrub community beetles dominated the early and midHolocene assemblages. Late Holocene assemblages contained both temperate and desert species. The region was apparently a refugium for desert biota during the late Pleistocene, its southerly latitude dampening the climatic effects of the Wisconsin glaciation, allowing the survival of desert species. A mosaic of temperate and xeric habitats persisted regionally, even during the last 1000 yr, when other parts of the desert experienced extremes of aridity.