.31" Triassic Fossil Avemetatarsalian (Dromomeron) Tooth - Texas

Dromomeron (meaning "running femur") is a genus of lagerpetid avemetatarsalian which lived around 220 to 211.9 ± 0.7 million years ago. It is known from partial remains, largely from the hind limbs, which indicate an animal with an overall length of 1 m (3 ft 3 in). The genus contains species known from Late Triassic-age rocks of the Southwestern United States and northwestern Argentina. It is described as most closely related to the earlier Lagerpeton of Argentina, but was found among remains of true dinosaurs like Chindesaurus, indicating that the first dinosaurs did not immediately replace related groups.

Based on the study of the overlapping material of Dromomeron and Tawa hallae, Christopher Bennett proposed that the two taxa were conspecific, forming a single growth series of Dromomeron. However, noting prominent differences between their femurs which cannot be attributed to variation with age, Rodrigo Muller rejected this proposal in 2017. He further noted that, while D. romeri is known from juveniles only, it shares many traits in common with D. gigas, which is known from mature specimens.