Xuanhanosaurus

File:Quadrupedal Xuanhanosaurus.png|thumb|left|250px|Xuanhanosaurus reconstructed in a quadrupedal position == Description ==

Xuanhanosaurus, originally thought to be around 6 m long, was approximately 4.8 meters (16 ft) in length, with a weight of 265 kilograms (585 lb). Xuanhanosaurus had powerful forelimbs, over 65 cm long; this, along with the retention of the fourth metacarpal in the hand, led Dong to suggest that Xuanhanosaurus might have walked on all four legs. If so, it would be the only known four-legged meat-eater among dinosaurs. Some recent work have notified that beyond the 4th metarcarpal, Xuanhanosaurus also retains ceratosaurian-like short phalanges II-1, similar in length to the ones recovered on Saltriovenator. The scapula was found to be bulkier than in Allosaurus. The distal humerus is enlarged laterally, forming a one-inch step. == Phylogeny ==

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. A more recent study by Benson and colleagues in 2010 found that it was more likely to be the most primitive known member of the Metriacanthosauridae family. 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. }} }} ==References==