Jinfengopteryx

Jinfengopteryx (from Jinfeng, 'golden phoenix', the queen of birds in Chinese folklore, and Ancient Greek πτερυξ pteryx, meaning 'feather') is a genus of 55 cm (2 ft) long maniraptoran dinosaur. It was found in the Qiaotou Formation of Hebei Province, China, and is therefore of uncertain age. The Qiaotou Formation underlies the more well-known Early Cretaceous Yixian Formation, so the Qiaotou Formation is either Early Cretaceous or Late Jurassic. Jinfengopteryx was preserved with extensive impressions of pennaceous feathers, but it lacks flight feathers on its hind legs, which are present in related dinosaurs such as Pedopenna.

Jinfengopteryx is known from one specimen (number CAGS-IG-04-0801), a nearly complete articulated skeleton with feather impressions. It also preserves several small, oval structures that are reddish yellow in color. These may be the remains of eggs, or nuts/seeds that the dinosaur had eaten.

Systematics
The authors of the original description considered Jinfengopteryx to be the most basal avialan (bird), and a member of the family Archaeopterygidae. In a 2007 follow-up paper, they went on to compare Jinfengopteryx and Archaeopteryx, still supporting its placement as an archaeopterygid, but providing no phylogenetic analysis. However, Luis Chiappe pointed out that Jingengopteryx appears to have more in common with the troodontids, such as an enlarged claw on its short second toe, and that numerous scientists suspect it may belong to that group. In 2006, Xu and Norell also suggested that Jinfengopteryx was a troodontid, based on general body plan and features of the teeth. In a 2007 analysis of the relationships between troodontids, dromaeosaurids, and early birds, Turner and colleagues did find Jinfengopteryx to be a troodontid, and referred it to that group, noting that it is the first troodontid specimen to preserve evidence of feathers.