What two specific bones in the *Xenotarsosaurus* ankle were found completely fused in the type specimen?
Answer
Astragalus and calcaneum
The most notable physical characteristic, which dictated the dinosaur's nomenclature, was the structure of its ankle. Paleontological examination of the recovered right hind limb showed that the *astragalus* and the *calcaneum*, which are the two primary components of the upper ankle complex, were entirely fused together. This fusion was so complete that no visible sutures remained between these two elements. This level of fusion in the ankle structure is considered highly unusual for theropods, distinguishing *Xenotarsosaurus* from many of its related species.
Related Questions
What does the generic name *Xenotarsosaurus* translate to based on its Greek roots?Which paleontologist was honored by the specific name *bonapartei*?In which Argentine geological feature were the *Xenotarsosaurus* fossils primarily discovered?What two specific bones in the *Xenotarsosaurus* ankle were found completely fused in the type specimen?What functional adaptation is theorized for the highly fused ankle structure in *Xenotarsosaurus*?What two types of skeletal elements constitute the limited known type specimens of *Xenotarsosaurus*?Which titanosaurian sauropod is mentioned as existing within the same ancient South American ecosystem as *Xenotarsosaurus*?What was the precisely measured length of the recovered right hind limb femur of *Xenotarsosaurus*?What alternative classification was proposed around 1989 for *Xenotarsosaurus* due to taxonomic uncertainty?What is the higher weight estimate cited in the comparative table for *Xenotarsosaurus*?The initial assignment of *Xenotarsosaurus* to Abelisauridae was based on hind leg similarities with which specific relative?What was the lower estimated length provided for *Xenotarsosaurus* in the size comparison table?