Zuolong sallleei (Choinere et al. 2010; IVPP V15912; Fig. 1; 3m in length) is a coelurosaur (related to Ornitholestes) dinosaur from the lower Oxfordian of the Late Jurassic.
the large reptile tree (LRT, 1209 taxa) nests Zuolong at the base of the rarely included Segisaurus/Marasuchus clade, near the origin of the Theropoda between Tawa and Sinocalliopteryx. Apparently taxon exclusion was a problem with the original Zuolong results.
Choiniere et al. counted 5 sacrals (Fig. 3).
The LRT finds only 4 sacrals (Fig. 3) when compared to the ilium, which has a truncated anterior, like that of fellow clade members. Most traits in Zuolong are common and plesiomorphic, as one might expect of a basal theropod.
At last! Skull material!
Zuolong is the first member of this near basal theropod clade (Segisaurus, et al.) known from substantial skull material… and it’s suitably plesiomorphic. Also note the truncated anterior ilium, a trait of this clade. Four sacrals down to two in smaller taxa separate clade members from most 5-sacral theropods.
Choiniere JN, Clark JM, Forster CA and Xu X 2010. A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People’s Republic of China. Journal of Vertebrate Paleontology. 30 (6): 1773–1796.