Asymmetrical pennaceous feathers are preserved attached to the wings, although they are shorter than in other enantiornitheans, being only twice the length of the hand. The most characteristic features of IVPP 21711, which the genus "Cruralispennia" was named after, are its crural (leg) feathers. These feathers are present on the tibiotarsus and possibly the femur, although overlap from body feathers makes the femur's integument uncertain. They are long and wire-like, consisting of a rachis-like structure seemingly formed from the fusion of a bundle of parallel barbs. This rachis-like structure forms 90% of the length of the feather. In the distal 10% of the feather's length, the individual parallel barbs become distinguishable, forming a brush-like tip. This form of feather morphology, dubbed "proximally wire-like part with a short filamentous distal tip (PWFDT)" , is also present in feathers projecting along the front edge of the left wing. PWFDT feathers are currently only known in "Cruralispennia," although they are similar to the ribbon-like tail feathers of the oviraptorosaur "Similicaudipteryx." It is probable that PWFDT feathers are a result of a genetic overexpression of the BMP4 gene (which promotes barb fusion and rachis formation) or a suppression of the Sonic hedgehog gene (which promotes the formation of individual barbs). Another possibility is that the PWFDT feathers are not a novel type of feather unique to "Cruralispennia", but instead are immature pennaceous feathers formed after a recent molt. There are several lines of reasoning supporting this hypothesis. With a long, thick rachis and minimal barbs at the tip, the PWFDT feathers resemble moderately developed pin feathers, which are known from modern birds as well as newly described juvenile enantiornitheans. In addition, they are interspersed with mature feathers, while truly unique feather types are expected to be separated from typical feathers. Many of the specimen's feathers are loosely attached or separated from the rest of the specimen, adding further evidence to the hypothesis that it was molting when it died. Structures believed to be fossilized melanosomes were found in five feather samples from the specimen using scanning electron microscopy. Due to their rod-like shape, they were identified as eumelanosomes, which correspond to dark shades.