Format: ORAL

Uxue Villanueva-Amadoz1, Brayan Bustamante2, Jeffrey G. Eaton3

1 Estación Regional del Noroeste (ERNO), Instituto de Geología, UNAM, 83000, Hermosillo, Mexico. E-mail: uxue@geologia.unam.mx 2 DICTUS, Universidad de Sonora, 83000, Hermosillo, Mexico 3 Natural History Museum of Utah, 301 Wakara Way, Salt Lake City, Utah 84108, USA

The Canaan Peak Formation, overlying the Campanian Kaiparowits Formation, in southern Utah (United States of America) is mostly conglomeratic unit with mudstone intervals containing plant debris and vertebrate remains (Bowers, 1972). This author indicated a lower or middle Campanian age for this formation on the basis of palynological assemblage studied by R.H. Tschudy due to its similarity to other palynological zonation in Montana, however, taxa are not determinative for this age. New palynological sampling from this dark grey mudstone interval yielded well-preserved palynomorphs, mainly composed by pollen grains (genera Alisporites, Carolinapollis, Fraxinoipollenites, Holkopollenites, Inaperturopollenites and Taxodiaceaepollenites, Discoidites parvistriatus, Rhoipites globosus, Tschudypollis retusus, among more common taxa) and scarce spores (Cyathidites minor, Laevigatosporites hardtii). The presence of Discoidites parvistriatus whose first apparance is the late Maastrichtian and K-taxa Tschudypollis retusus suggests a late Maastrichtian age.