Archaeopteryx airfoil. This would have reduced stall speed by up to 6% and turning radius by up to 12%. The feathers of "Archaeopteryx" were asymmetrical. This has been interpreted as evidence that it was a flyer, because flightless birds tend to have symmetrical feathers. Some scientists, including Thomson and Speakman, have questioned this. They studied more than 70 families of living birds, and found that some flightless types do have a range of asymmetry in their feathers, and that the feathers of "Archaeopteryx" fall into this range. The degree of asymmetry seen in "Archaeopteryx" is more typical for slow flyers than
Specimens of Archaeopteryx that "Archaeopteryx" could have raised its short second toe in a similar manner to its dromaeosaur cousin "Deinonychus", whose second toe bore an enlarged "sickle claw" for probable use in predation. It remains unclear whether "Archaeopteryx" also used its hyperextended toe-claw in a similar fashion or for some other purpose. Taken together, many of the unique features of the skull, feet and coracoid strengthen a close relationship of archaeopterygids to deinonychosaurian theropods. Well-preserved imprints of wing and tail plumage show details of the barbs, but not barbules, and the shafts of 11 primaries can be counted on the right wing.