Paraves

Paraves is a widespread group of bird-like theropod dinosaurs that originated in the Middle Jurassic. It includes the dromaeosaurids, troodontids, and anchiornithids, possibly the scansoriopterygids, and the avialans, the last of which encompass Archaeopteryx and the more than 11,000 species of living birds. Its members are small, gracile, feathered animals, and many bear long winged forelimbs, though these became reduced in flightless forms and in lineages that branched off before the origin of flight. The best-known paravian trait is an enlarged, strongly curved sickle-shaped claw on the second toe, held clear of the ground when walking; in many basal forms only the third and fourth toes bore the animal's weight. Most of the earliest members were carnivorous, though some smaller troodontids and early avialans were omnivorous. The precise relationships among paravian groups remain an active subject of research.