What specific anatomical feature of Xenotarsosaurus gives rise to its descriptive name?

The unusual morphology of the tarsal bones in the ankle joint

The defining feature leading to the naming of Xenotarsosaurus is the architecture of its ankle joint, specifically the tarsal bones—the collection of small bones comprising the ankle. This configuration deviates significantly from the typical arrangement observed in many other predatory dinosaurs of the time. While ankle structures in small theropods are often specialized for running, the specific architecture in Xenotarsosaurus suggests a unique mechanical articulation in its lower leg and foot. This strange structure implies a distinct gait or locomotion strategy that was optimized for its particular environment, perhaps offering enhanced stability during movement.