Protoavis are well preserved, and they are astonishingly non-avian. The distal carpals, while long, are in no way similar to those observed in the urvogel or other archaic birds. There is no semilunate element, and the structure of the radiale and ulnare would have limited the flexibility of the wrist joint. The manus is not tridactyl, and metacarpal V is present. In even the most basal avialian, "Archaeopteryx", there is no vestige of the fifth metacarpal and its presence in "Protoavis" seems incongruous with the claim that it is a bird, let alone one more derived than "Archaeopteryx". Chatterjee claims that
Ruppert Archaeopteryx Ruppert Archaeopteryx The Ruppert Archaeopteryx () is a Swiss high-wing, pod-and-boom, single-seat, microlift glider that was designed by Roger Ruppert and is produced by Ruppert Composite GmbH. The aircraft is named for the feathered Archaeopteryx dinosaur. The Archaeopteryx was conceived as a foot-launchable microlift sailplane, with the design goals of a light empty weight, low stall speed with gentle stall characteristics, good maneuverability and good high speed performance. A further goal was a sailplane that could be foot-launched in zero wind conditions. The Archaeopteryx design started in 1998 at the Zurich University of Applied Sciences (ZHW) as a research project.