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292 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
D
B
FIGURE 4.—Comparisons of the first phalanx of the second manual digit in dorsal view: A, Ornitholestes hermanni
Osborn (modified from Osborn, 1917); B, Deinonychus antirrhopus (modified from Ostrom, 1976); c,
Archaeopteryx bavarica Wellnhofer (modified from Wellnhofer, 1993); D, Confuciusomis sanctus Hou et al.
(from a cast of the holotype of Confuciusomis); E, Cathayornis yandica Zhou et al. (modified from Zhou et al.,
1992); F, Meleagris gallapavo Linnaeus. Drawings not to scale.
shorter in the theropods. In addition to the differences mentioned
by Ostrom, Archaeopteryx has many advanced avian attributes
of the wrist and hand, with the complex and peculiar
pattern of the avian carpometacarpus already formed at this
early stage of avian evolution. Without these specializations,
the attachment of the primary feathers to the hand would be
hardly imaginable, let alone flight.
Vazquez (1992) discussed the functional morphology of the
avian wrist and stated that Archaeopteryx lacks many of the
features of modem birds and was probably incapable of executing
all the kinematics of modern avian powered flight. Although
we might agree that modem birds have a wrist better
designed for powered flight, Archaeopteryx is not so deficit in
those features as Vazquez (1992) supposed. As shown by Martin
(1991), Archaeopteryx has a basically avian wrist, with all
of the bones found in modern birds, including an L- or Vshaped
cuneiform (ulnare) to glide on the articular ridge of the
carpometacarpus. This fact has been missed by most workers,
including Martin (1983), because the preservation in Archaeopteryx
usually shows only the dorsal or ventral side. Fortunately,
the Eichstatt specimen (Wellnhofer, 1974, figs. 8, 9)
presents palmar and anconal (ventral and dorsal) views of the
same specimen. In palmar view the ulnare is large and elongate;
in anconal view it is small and round. It could therefore
be either pyramid-shaped, which would make it unlike the
shape of any known relative, including other birds or dinosaurs,
or L-shaped as in modem birds but not in dinosaurs. We
accept the L-shaped interpretation.
The perching capability of Archaeopteryx has recently been
argued with strong evidence (Feduccia, 1993). The wing claws
in Archaeopteryx are long and curved. The first digit diverges
from the others (Zhou, 1995). The manual digits are relatively
slender. All these characters, in combination, seem to show an
overwhelmingly avian pattern and show that the wings could
not have been used for predation (Ostrom, 1974). It seems
more reasonable to suggest that the oldest bird, although limited
in flying power, lived an arboreal life just as do most modem
birds, with its wings used for both flight and climbing.
The appearance of feathers was the critical point in avian
evolution, and the modern appearance of the feathers in Archaeopteryx
has often been noted (Feduccia and Tordoff, 1979;
Norberg, 1995). The close match of the bones of the wrist and
manus with modem birds suggests that flight played a vital role
in the early evolution of birds. Furthermore, there was coevolution
of the skeleton and feathers as two inseparable parts of the
flight mechanism.
The recognition of many avian characters in Archaeopteryx
is important not only for identifying more fragmentary fossils
but also for recognizing potential protobirds from even older
strata. Because more and more people believe that Archaeop-