PRELIMINARY RESULTS OF PALEONTOLOGICAL INVENTORY OF CHACO CULTURE NATIONAL HISTORICAL PARK, NEW MEXICO

Situated in the southern San Juan Basin of northwestern New Mexico, Chaco Culture National Historical Park (CCNHP) is well known for its rich archaeological record and cultural significance. Although the park also preserves a diverse fossil record of terrestrial and marine ecosystems resulting from repeated sea level fluctuations of the Western Interior Seaway during the Late Cretaceous, the extent and significance of paleontological resources outside of a cultural context has largely been overlooked until the last decade. Since 2005, ongoing surveys of the Campanian age Mesaverde Group within CCNHP have revealed abundant and extensive paleontological resources not previously known, shedding light onto the scientific significance and potential of fossil bearing strata in the area. As of 2014, 302 fossil localities have been identified and mapped within the park’s 33,960 acres, including 148 plant, 95 vertebrate, 49 invertebrate, and 10 mixed-fossil localities. The two most prominent and fossiliferous rock units within the park are the Menefee Formation and Cliff House Sandstone. The Menefee Formation (~80 Ma), a terrestrial mudstone and shale unit representing a deltaic and coastal plain, contains an abundance of plant and vertebrate fossils including petrified wood of angiosperm and gymnosperm trees with fossilized termite burrows, fossil leaves, pelomedusid and trionychid turtles, crocodilians, and hadrosaurian, theropod, and possible ceratopsian dinosaurs. The Cliff House Sandstone (~77 Ma), a marine sandstone representing a beach and shallow sea is abundant in invertebrate fauna including bivalves, gastropods, ammonites, and Ophiomorpha nodosa traces. Paleoflora includes fossil wood and reed molds. Vertebrate remains are extensive but sporadic and include abundant shark teeth and fish vertebrae. Notable vertebrate fossils in the Cliff House Sandstone consist of the remains of marine reptiles including mosasaurs and plesiosaurs. Very little research has been done on the paleoflora and fauna of the formations present at CCNHP, but the preliminary results of the paleontological resources inventory indicate that the potential for new and scientifically significant fossil material is very high, especially in the relatively understudied Menefee Formation.