Zuolong salleei was discovered in 2001, and was described in 2010 by Jonah N. Choiniere, James M. Clark, Catherine A. Forster, and Xing Xu.
The holotype was discovered in 2001 in Wucaiwan Village of Changji Hui prefecture, in the Xinjiang Autonomous Prefecture of China.
Zuolong is a basal coelurosaur from the Shishuguo Formation. Previous tests of sediment from what is above and below the specimen's depth dated the lower rock to be from the Callovian age, with the upper rock being Oxfordian. Since the specimen was found closer to the upper reading depth, Zuolong is thought to be from the Oxfordian age. Coelurosaurs are the branch of theropods that eveolved into birds.
The holotype consists of a partial skull (missing most of the lower jaw) with three teeth, a few vertebrae, a proximal forelimb, and a proximal hindlimb. Judging by the sizes of the femur and cranium, the length of Zuolong is estimated to be around 3.12m, and the weight somewhere in between 16.22kg and 50.38kg, with an official estimation around the middle at 34.25kg. Thomas R. Holtz stated in 2012 that he believes the holotype to be from a juvenile.
Comparing Zuolong with 60 other specimens (40 relating to coelurosaurians) has found it to be possibly the most basal coelurosaurian, or at least pretty close.
The teeth of Zuolong appear to be curved backwards, as with other theropods, and have small rectangular denticles on ridges along the length of the teeth. This evidence points to a carnivorous diet.
Zuolong comes from General Zuo (or General Tso), a Chinese general from the Qing Dynasty who conquered parts of Xinjiang, and the Chinese for dragon, "long". Salleei refers to Hilmar Sallee, whose bequest (money given through a will) helped fund the expedition. Information can't be found about Hilmar Sallee, unless he is a previous Boradway assistant manager who died in 1998.