G-47 PLIOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT

In 1935, vertebrate fossils were first found in Arroyo de la Parida, about 6 km northeast of Socorro, Socorro County. Needham (1936) reported a complete pair of lower jaws of the gomphotheriid proboscidean Rhynchotherium and a lower molar of the horse Plesippus (now considered a subgenus of Equus) from an exposure of sands and gravels of the Santa Fe Group on the southern side of Arroyo de la Parida, about 2 km east of its confluence with the Rio Grande. Additional vertebrate fossils were collected from this same exposure by students from the Ne