INVESTIGATION OF PALEONTOLOGICAL RESOURCES AT AMISTAD NATIONAL RECREATION AREA

Steep canyons of Cretaceous limestone surround Amistad National Recreation Area. Located on the border between the United States and Mexico in southwestern Texas, Amistad NRA has a rich paleontological record that remains relatively unexplored. Fossils consist primarily of marine invertebrates from the Upper and Lower Cretaceous; however, rock shelters utilized by indigenous people in the Quaternary preserved an array of Chihuahuan Desert wildlife. Stratigraphic units exposed inside the park include the Salmon Peak Limestone, Devils River Limestone, Del Rio Clay, Buda Limestone, and Boquillas Formation. Though paleontological discoveries are not uncommon in these Cretaceous deposits, limited records exist for fossils found on National Park Service land.

This report serves as a primary investigation of Amistad NRA paleontological resources. Field work completed in March 2006 covered 24 in-park localities, 8 Val Verde County road-cuts, and 2 neighboring sites managed by the Shumla School. Fossils derived from Cretaceous units were the focus of field studies as numerous publications detail Quaternary fauna and flora unearthed during archaeological investigations. Prevalent fossils at Amistad NRA comprise rudist bivalves, high-spired snails, and Ilymatogyra arietina oysters. Fragmentary echinoids, ammonoids, pectinids, bryozoans, and burrows are commonly found as well. Previous reports indicate the presence of microfossils such as milioid forams, ostracodes, and algae. Select fossils recovered inside park boundaries were accessioned in the collections at Amistad NRA and records for pre-existing fossils housed at the park were updated. Five particularly significant park areas are in the process of being registered as official NPS localities offering the potential for heightened protection and preservation of in situ paleontological resources. Though interpretation mainly highlights the renowned rock art of the region, opportunities to increase paleontological education and awareness at Amistad NRA are plentiful. Documentation of localities and improved fossil identification resulting from this research along with a shared interest in developing paleontological programs through the Shumla School impart a strong basis for the future of paleontology at Amistad National Recreation Area.