Xiaotingia

Xiaotingia is an extinct genus of Archaeopteryx-like theropod dinosaur from early Upper Jurassic deposits of western Liaoning, China.

The Chinese team claims the fossils dated to 155 million years ago (mya), whereas the Solnhofen limestone where Archaeopteyx was found is 144 mya in age. The  new fossil Xiaotingia cannot be dated so accurately, as they were originally been purchased from a dealer. Prof Xu first saw the specimen at the Shandong Tianyu Museum. The other question to be asked of all early dinobirds is: could they fly? 

A cladistic analysis by Xu and his team showed that Xiaotingia formed a clade with Archaeopteryx, the Dromaeosauridae and the Troodontidae. This clade excludes other birds.  They therefore (re)defined the concepts of Deinonychosauria and Avialae so Archaeopteryx and Xiaotingia belonged to the Deinonychosauria and Archaeopteryx no longer was an avian (bird). This led to popular reports that "Archaeopteryx is no longer a bird".McGrath, Matt 2011. Feathers fly in first bird debate. BBC Science  

However, the team explicitly allowed for a traditional Aves with Archaeopteryx as a specifier. Such a clade would in their opinion include the Deinonychosauria.

 References 

Category:Jurassic dinosaurs
Category:Coelurosaurs
Category:Feathered dinosaurs