The raptor's famous sickle claw was probably a grappling hook, not a blade
For decades the curved toe claw of Deinonychus and its kin was pictured slicing open giant prey. Close study of the claw's shape says otherwise: its underside was barely keeled and useless for cutting. Instead these paravian dinosaurs likely pinned victims under their weight, the way hawks and eagles still do.
Paraves is the branch of theropod dinosaurs closer to birds than to oviraptorosaurs. Its members include dromaeosaurids, troodontids, anchiornithids and the avialans, a line that runs through Archaeopteryx to more than 11,000 living bird species. Paul Sereno coined the name in 1997, from Greek for beside and Latin for birds. The group arose in the Middle Jurassic, and how its sub-branches fit together is still argued over as fresh fossils appear.
Many early paravians walked on only two toes. Fossil trackways show dromaeosaurids, troodontids and some early avialans holding the second toe raised and hyperextended, carrying its big curved claw off the ground. Early interpretations cast it as a disembowelling weapon. In 2006 Manning and colleagues argued it worked more like a climbing crampon, and a larger 2011 study by Fowler's team agreed it was a poor cutter. Comparing with modern birds of prey, they proposed that advanced dromaeosaurids stabbed and gripped animals no larger than themselves, holding them down while flapping and using the tail for balance. Teeth with big hooked serrations only on their rear edges fit this picture of tearing rather than slicing.
Shrinking was central to the story. Paravian ancestors began getting smaller about 200 million years ago in the early Jurassic, and fossils suggest the line evolved new features four times faster than other dinosaurs while shrinking 160 times faster than other lineages were growing. The common ancestor may have been about 65 centimetres long and weighed 600 to 700 grams. Later, dromaeosaurids grew large three separate times and troodontids once.
Several early paravians, most famously Microraptor gui, carried long flight feathers on their legs as well as their arms, earning the nickname four-winged dinosaurs. Although such hind wings seemed to demand a life in trees, there is little sign these animals climbed, and later work showed Microraptor could flap and launch itself from the ground. It may even represent flight evolving separately from the bird line. A 2018 eggshell study also found traces of colour pigment, suggesting some non-bird relatives laid speckled eggs.
Source: Paraves
