Xuanhanosaurus

Xuanhanosaurus (meaning "Xuanhan lizard") is a genus of theropod dinosaur that lived during the Middle Jurassic (Bathonian) of the Sichuan Basin, China, around 166 million years ago.

[3] Although it has been known for more than 40 years, this taxon has been the subject of very few studies, although most seem to agree that it is a tetanuran, possibly a basal allosauroid, highlighting the fact that it has a vestigial fourth metacarpal.

It consists of a partial skeleton without a skull, namely a scapula missing the posterior end, coracoid, a possible sternum humerus, radius, ulna, manus, as well a few fragmentary dorsal vertebrae.

[10] Originally, Xuanhanosaurus was assigned by Dong to the Megalosauridae, when this group was meant to include a larger amount of taxa, and was argued to be in the middle stage of the evolution of the Tetanurae due to its vestigial fourth metacarpals.

[4] In 2018, based on several conditions such as the length and retention of the vestigial 4th metacarpal, it was argued that this taxon and "Szechuanosaurus" zigongensis belong to early-diverging branches of the ceratosaurian-tetanuran node.

Xuanhanosaurus reconstructed in a quadrupedal position [ 3 ] which is now considered outdated. [ 4 ]
An X. qilixiaensis specimen compared to an average human male