New Mexico Geological Society Annual Spring Meeting — Abstracts

A locality in the Coniacian Dalton Sandstone along the Rio Puerco in Bernalillo County, New Mexico (T11N, R2W) yields numerous teeth of selachians in addition to other vertebrate fossils. The selachian fauna is composed of Pseudohypolophus sp., Scapanorhynchus raphiodon, Squalicorax kaupi. Ptychotrygon triangularis, Ptychodus mortoni, and Ischyrhiza mira. Teeth of Pseudohypholophus sp., a benthic predator, are the dominant selachian tooth type at this locality. Other benthic taxa, Ptychotrygon triangularis, Ptychodus mortoni, and Ischyrhiza mira are rare. The pelagic selachian fauna from this locality is dominated by Scapanorhynchus raphiodon. Squalicorax kaupi is a common element in this fauna. This site has also yielded selachian vertebrae and coprolites, abundant Trionychidae and Baenidae? shell material, thick ganoid gar scales, teleost cranial material, and mosasaur teeth. The selachian fauna from the Dalton Sandstone is very similar to that from the Santonian Hosta Tongue of the Point Lookout Sandstone. Indeed, despite their age difference, the Dalton and Hosta appear to have essentially identical selachian faunas; what differences exist can be explained by taphonomic and sampling differences.