Sinosauropteryx
"Sinosauropteryx" was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to in length, with an estimated weight of It was a close relative of the similar but older genus "Compsognathus", both genera belonging to the family Compsognathidae. Only one species of "Sinosauropteryx" has been named: "S. prima", meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.
Shuangbaisaurus
A further issue in the relation between "Shuangbaisaurus" and "Sinosaurus" involves the taxonomic convolution that has befallen "Sinosaurus". At least one species is recognized in the genus, "Sinosaurus triassicus", consisting of specimens LFGT LDM-L10 and LFGT ZLJT01; another specimen, KMV 8701, originally named "Dilophosaurus" "sinensis", has been referred to either "S. triassicus" or a second species "S. sinensis". KMV 8701 approaches "Shuangbaisaurus" more closely in its tall skull and premaxilla than specimens referred to "S. triassicus". Wang "et al." elected to retain "S. sinensis" as a separate species owing to these differences. No phylogenetic analysis has been conducted to quantitatively determine the relationships of "Shuangbaisaurus".