Dromomeron gregorii Nesbitt et al., 2009b

Dromomeron gregorii Nesbitt et al., 2009b

AGE:?Carnian–early Norian, Late Triassic ( Lucas, 1998a).

OCCURRENCE: Otis Chalk Quarry 3 (TMM 31100), Howard County, Texas ; Placerias Quarry , Arizona.

HOLOTYPE: TMM 31100-1306, right femur.

Paratypes: TMM 31100-464, right femur ; TMM 31100-1308, right femur ; TMM 31100- 1234, right femur ; TMM 31100-764, right femur ; TMM 31100-278, right tibia ; TMM 31100-1314, left tibia .

REFERRED MATERIAL: UCMP 25815, distal portion of a left femur from the Placerias Quarry.

REMARKS: Nesbitt et al. (2009b) described a second taxon of Dromomeron from the base of the Dockum Group; D. gregorii and D. romeri are separated stratigraphically. D. gregorii shows that non-dinosaurian dinosauromorphs were present throughout much of the Late Triassic sediments in the southwestern United States. Like D. romeri , D. gregorii is currently known only from hind limb material. D. gregorii and D. romeri are found as sister taxa in a clade with Lagerpeton to the exclusion of all other archosaurs in Nesbitt et al. (2009b).

Dromomeron gregorii differs from Dromomeron romeri in possessing a distinct ridge for the attachment of the M. caudifemoralis longus ( 5 4th trochanter), the presence of an anterior trochanter and trochanteric shelf, robust proximal and distal ends of the femora, the intercondylar groove of the distal femur is reduced to a slit in larger specimens (possible autapomorphy), and the lack of an anteromedial concavity on the distal end of the tibia.

KEY REFERENCES: Nesbitt et al., 2009b.