Many other dromaeosaur fossils have been found with feathers covering their bodies, some with fully-developed feathered wings. "Microraptor" even shows evidence of a second pair of wings on the hind legs. While direct feather impressions are only possible in fine-grained sediments, some fossils found in coarser rocks show evidence of feathers by the presence of quill knobs, the attachment points for wing feathers possessed by some birds. The dromaeosaurids "Rahonavis" and "Velociraptor" have both been found with quill knobs, showing that these forms had feathers despite no impressions having been found.