New Mexico Geological Society Annual Spring Meeting — Abstracts

Rocks referable to the Lower Mancos Shale, Upper Cretaceous, are exposed throughout the town of Shiprock, New Mexico. These deposits typically yield marine invertebrates, most notably Inoceramus. Two large bone fragments were found in a wash which passes under NM 666. A 17 cm long distal tibia fragment with a weathered articular surface has been identified. The second fragment, > 20 kg, has been identified as a sauropod femur cross-section. It is uncertain whether these specimens represent the same animal.

The femur fragment and the proximal end of the tibia fragment are well preserved and the condition of the fractures indicate that other pieces should be near by. Searches in the stream bed have not uncovered the missing pieces but spring floods may. Both fragments have attached matrix. A preliminary search failed to locate the lens from which the bones eroded. In consulting with Spencer Lucas, New Mexico Museum of Natural History and Science we decided that the bones were probably driven to the wash and dumped. No further field work is planned.