What specific autapomorphy, a unique derived trait, was identified to provisionally validate the Xiaosaurus genus?
Answer
A mediolaterally straight humerus
The genus *Xiaosaurus* faced skepticism regarding its validity due to the fragmentary nature of its fossils, leading some to label it a *nomen dubium*. A key turning point in validating the genus came from a 2005 review which concluded it was provisionally valid because it possessed at least one autapomorphy—a unique, derived trait not shared with its closest relatives. This distinguishing feature was identified specifically as a mediolaterally straight humerus, referring to the upper arm bone when viewed from the front. This singular anatomical characteristic provided enough evidence to suggest the specimen represented a distinct genus rather than just poorly preserved remains of another known dinosaur.
Related Questions
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