Early Jurassic theropod footprints in SW China shed new light on dinosaur behavior

BEIJING -- A landmark study of 413 early Jurassic theropod footprints discovered in Southwest China's Sichuan province has provided unprecedented insights into the behavior and movement of these carnivorous dinosaurs.

Published in the latest issue of the Journal of Palaeogeography on Friday, the study suggests that these early theropods may already have exhibited complex behaviors and movement patterns remarkably similar to modern birds.

The research focused on an exceptional tracksite in Fushun county in Sichuan, where eight stone slabs have preserved an extraordinary density of three-digit footprints.

According to Xing Lida, an associate professor at China University of Geosciences (Beijing), the tracks are primarily classified as Grallator, averaging 14.5 centimeters in length -- with some larger specimens, identified as Eubrontes, reaching up to 22.5 centimeters.

The study's most significant finding comes from detailed biomechanical analysis indicating these small theropods had employed a "ground-running" gait comparable to modern birds -- managing estimated speeds between 5.8 and 8.6 kilometers per hour. This discovery provides crucial evidence for understanding the evolutionary pathway from dinosaurs to avian locomotion, Xing said.

Equally important was the identification of rare tail drag marks alongside these footprints. These traces, measuring 20 to 40 centimeters long and 2 to 3 centimeters wide -- represent one of the few documented cases of bipedal dinosaur tail impressions.

Xing suggested these marks likely resulted from theropods moving slowly in lakeside environments, possibly while pausing to observe their surroundings or during social interactions that involved aggressive displays.

"This research fundamentally advances our understanding of early Jurassic ecosystems in the Sichuan Basin," Xing noted.

It not only provides a critical Asian record of globally recognized footprint types -- but also suggests that complex avian-like behaviors and locomotion capabilities could have appeared much earlier in theropod evolution than previously recognized, he added.