Dromomeron gregorii Nesbitt et al., 2009b

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 44-45

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.