China, Early Cretaceous (120–125 million years ago), described 1999
Around 1 metre long when fully grown, Sinornithosaurus was a small predatory dromaeosaur related to Deinonychus and Velociraptor. The first specimen was discovered by a team including Xu Xing in 1999 and became the fifth feathered species of dinosaur found in western Liaoning. The fossils have downy feathers covering much of the body and more-developed quills on the arms and tail. A 2009 study proposed that the species may have been venomous (as seen in the video above), injecting poison via fangs in a similar way to a snake, but this has not been widely accepted. A second species, S. haoiana, was described in 2004. Sinornithosaurus (SINE-or-nith-o-SOR-us) milleni means ‘millennium Chinese bird lizard’.
Video courtesy of the BBC Earth YouTube Channel and originally from the fantastic Planet Dinosaur documentary series.