New Mexico Geological Society Annual Spring Meeting — Abstracts

The goniopholidid crocodylian "Goniopholis" kirtlandicus is based on a partial skull from the Upper Cretaceous Kirtland Formation. Isolated teeth and osteoderms from a large goniopholidid are relatively common in the Fruitland and Kirtland Formations and have been referred to this taxon. Additional remains of a large goniopholidid including associated dorsal osteoderms and dorsal vertebrae, isolated limb elements, and associated osteoderms and a partial dentary are reported here. These specimens add new information about the "mesosuchian" crocodilian from the Fruitland and Kirtland Formations. Typical goniopholidid dorsal osteoderms from the Fruitland and Kirtland Formations are extremely transverse, flat, marked with large and deep pits on the dorsal surface, have large overlap areas, and lack lateral articular surfaces. Dorsal vertebrae are amphicoelus and have very elongate lateral processes. A complete right femur (P-31551) is relatively large (length = 280 mm) and robust and bears a well-developed deltoid crest. A partial edentulous right dentary (NMMNH P-30064), is the first reported for a Late Cretaceous goniopholidid from North America. It is relatively large (preserved length =427 mm) and robust (maximum transverse diameter behind symphysis =78 mm; maximum depth =88 mm; length of symphysis =143 mm). Ten complete or partial alveoli are preserved. The third and fourth alveoli are subequal (length = ~30 mm; width = ~18 mm), partially confluent with raised margins, and are the largest of the tooth row. The other alveoli are relatively widely spaced. The alveoli posterior to this are relatively small (length of the fifth alveolus =13 mm; width of the fifth alveolus =11 mm) and decrease in size posteriorly. The first two alveoli are nearly the diameter of the third and fourth. Two associated osteoderms are circular, relatively thick, and dorsally convex with large and deep pitting on the dorsal surface. They may represent dorsal armor from the cervical region.

Goniopholidid remains are relatively more abundant in the coastal, more marine-influenced Fruitland and lower Kirtland Formations (Hunter Wash and Farmington Members) than in more upland deposits represented by the upper Kirtland Formation (De-na-zin and Naashoibito Members) suggesting that it preferred costal habitats.