INSECT FOSSIL EVIDENCE OF LATE-GLACIAL AND HOLOCENE ENVIRONMENTS IN THE BOLSON-DE-MAPIMI, CHIHUAHUAN-DESERT, MEXICO - COMPARISONS WITH THE PALEOBOTANICAL RECORD

This paper discusses fossil insect studies from the Bolson de Mapimi r egion in. the southern Chihuahuan Desert of Mexico. Fossil packrat mid dens from three study areas were analyzed, providing paleoenvironmenta l reconstructions of late Wisconsin to late Holocene age. Paleoflorist ic analyses of late Wisconsin samples from true of the three areas hav e been published; the insect results are in good agreement with the pa leobotany. The late glacial assemblages comprise a mixture of temperat e and desert taxa, in addition to some tropical and subtropical elemen ts. In contrast to faunas from other Chihuahuan Desert regions, only o ne temperate species was found in the late glacial assemblages. Follow ing a temporal hiatus (12,000-9000 yr BP), most of the late glacial fa una disappears from the records. Desertscrub community beetles dominat ed the early and mid-Holocene assemblages. Late Holocene assemblages c ontained 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 xer ic habitats persisted regionally, even during the last 1000 yr, when o ther parts of the desert experienced extremes of aridity.