A record of Late Jurassic vertebrates from Texas

Abstract

ABSTRACT We present the first description of Jurassic vertebrate fossils from Texas. The vertebrate specimens were collected from the Upper Jurassic Malone Formation in the Malone Mountains of western Texas. The specimens are fragmentary and not particularly diagnostic, but probably represent elements of plesiosaurians. One specimen is similar to the caudal vertebra of a pliosaurid plesiosaurian, whereas another may be a partial propodial of a small plesiosaurian. Additional bone fragments are not identifiable at this time. These vertebrates were discovered along with abundant plant and invertebrate fossils. Previous studies of the invertebrate fossils indicate a Kimmeridgian to Tithonian age for the Malone Formation, which is consistent with a single grain age of 151±2 Ma from detrital zircon U–Pb geochronology obtained in this study. The Malone Formation was deposited in shallow marine to marginal marine environments along the northern edge of the Chihuahua trough. It is correlative with the La Casita and La Caja Formations of northern Mexico, where similar marine vertebrates have been reported. The Malone Formation is also correlative with the Morrison Formation to the north.