Stratigraphic studies of the Difunta group (Gulfian-Midwayan) have disclosed approximately 11,000 ft. of strata which contain abundant dinosaur and marine molluscan remains in close association at one locality within the Parras basin. This locality is quite inaccessible. The mollusks (Ostrea sp., Inoceramus sp., Sphenodiscus lenticularis, etc.) occur 50 ft. above the dinosaur horizon (Monoclonius sp., etc.) but their stratigraphic position in the lower Difunta is unknown. The fossils indicate Tayloran-Navarroan age for these beds.