archaeopteryx

/ahr'kee op"teuh riks/, n.

a reptilelike fossil bird of the genus Archaeopteryx, from the late Jurassic Period, having teeth and a long, feathered, vertebrate tail. Cf. protoavis.

[1855-60; < NL < Gk archaio- ARCHAEO- + ptéryx wing]

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Oldest known fossil animal that is generally accepted as a bird (classified as genus Archaeopteryx).

It flourished during the Late Jurassic period (159–144 million years ago). Fossil specimens indicate that archaeopteryx ranged in size from as small as a blue jay to as large as a chicken. Archaeopteryx shared anatomical characteristics with both birds (well-developed wings and birdlike skull) and theropod dinosaurs (well-developed teeth and a long tail).

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▪ fossil bird

  the oldest-known fossil animal that is generally accepted as a bird. The eight known fossil specimens date to the Late Jurassic Period (161 million to 146 million years ago), and all were found in the Solnhofen Limestone Formation in Bavaria, Germany. Here a very fine-grained Jurassic limestone formed in a shallow tropical marine environment (probably a coral lagoon), where lime-rich muds slowly accumulated and permitted fossil material to be exceptionally well preserved. Several of the fossils show clear impressions of feathers. The sizes of the specimens range from that of a blue jay to that of a large chicken.

      Archaeopteryx shared many anatomic characters with coelurosaurs, a group of theropods (theropod) (carnivorous dinosaurs). In fact, only the identification of feathers on the first known specimens indicated that the animal was a bird. Unlike living birds, however, Archaeopteryx had well-developed teeth and a long well-developed tail similar to those of smaller dinosaurs, except that it had a row of feathers on each side. The three fingers bore claws and moved independently, unlike the fused fingers of living birds.

      Archaeopteryx had well-developed wings, and the structure and arrangement of its wing feathers—similar to that of most living birds—indicate that it could fly. Skeletal structures related to flight are incompletely developed, however, which suggests that Archaeopteryx may not have been able to sustain flight for great distances. Archaeopteryx is known to have evolved from small carnivorous dinosaurs, as it retains many features such as teeth and a long tail. It also retains a wishbone, a breastbone, hollow, thin-walled bones, air sacs in the backbones, and feathers, which are also found in the nonavian coelurosaurian relatives of birds. These structures, therefore, cannot be said to have evolved for the purpose of flight, because they were already present in dinosaurs before either birds or flight evolved.

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