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Origins of Birds
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 Achaeopteryx: the ancient wings |
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Archaeopteryx: (from Ancient Greek archaios meaning “ancient”, and pteryx meaning “wing”, is a very early prehistoric bird, dating from the late Jurassic Period about 155-150 million years ago, when many dinosaurs lived. It is one of the oldest-known birds. Archaeopteryx was similar in size and shape to a magpie or crow, with broad, rounded wings and a long tail, and reached up to 2 feet (0.6 meters) in length with a wingspan of 1.5 feet (0.5 meters), and probably weighed from 11 to 18 ounces (300 to 500 grams), the brain was relatively large for an animal of that epoch. Its feathers resembled those of modern birds but Archaeopteryx was rather different from any bird known today, in that it had jaws lined with sharp teeth, three 'fingers' ending in curved claws and a long bony tail, may have been able to fly, but not very far and not very well. |
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In 1862, the description of the first intact specimen of Archaeopteryx, just two years after Charles Darwin published The Origin of Species, set off a firestorm of debate about evolution and the role of transitional fossils that endures to this day. Paleontologists think that Archaeopteryx was a dead-end in evolution and that coelurosaurian theropods (a group of dinosaurs that included the Dromaeosaurs Deinonychus, Utahraptor, and Velociraptor) led to the birds. |
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 The Berlin Archaeopteryx,1881 |
Fossils: Amazingly detailed Archaeopteryx fossils have been found in fine-grained Jurassic limestone in southern Germany. This fine-grained limestone is used in the lithographic process, hence the species name "lithographica" given to the early Archaeopteryx specimen. The first Archaeopteryx fossil (a feather) was found in 1860 near Solnhofen, Germany, and was named by the German paleontologist Hermann von Meyer in 1861. That year he also discovered the first specimen of Archaeopteryx. A total of eight Archaeopteryx specimens have been found, plus the feather. The Solnhofen area was a stagnant lagoon during the Jurassic period (Europe was a series of islands at this time). The lagoon's waters had little or no oxygen (anoxic) near the bottom, a situation that helped preserve many dead organisms, and boost the chances of fossil formation, since decay after death is very slow in anoxic waters. |
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Bird fossils are rare because bird bones are hollow and fragile, and usually deteriorate instead of fossilizing. However, a few Jurassic, mid-Cretaceous, Eocene and Miocene-Pliocene bird fossils have been found. |
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The Origin of Birds: In 1868, Thomas Henry Huxley interpreted the Archaeopteryx fossil to be a transitional bird having many reptilian features. Using the fossils of Archaeopteryx and Compsognathus, a bird-sized and bird-like dinosaur, Huxley argued that birds and reptiles were descended from common ancestors. Decades later, Huxley's ideas fell out of favor, only to be reconsidered over a century later (after much research and ado) in the 1970's. In 1986, J. A. Gauthier looked at over 100 characteristics of birds and dinosaurs and showed that birds belonged to the clade of coelurosaurian dinosaurs. (Gauthier, J.A., 1986. |
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Saurischian monophyly and the origin of birds, in: The Origin of Birds and the Evolution of Flight, California Academy of Sciences Memoir No. 8) Classification: |
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Archaeopteryx: is probably close to the ancestry of modern birds because it had feathers. It shows most of the features one would expect in an ancestral bird and retained many dinosaurian characters which are not found in modern birds, but it may not be the direct ancestor of living birds, and it is arguable how much divergence was already present in the early birds at its time. However the some of modern birds: Helmeted hornbill shows the features of oldest bird and seem as dinosaurian characters and found in hornbill birds. |
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