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Eodromaeus, small predatory dinosaurs of dawn |
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Researchers have discovered a new representative of the dinosaurs the Eodramaeus, who lived early in their era there are about 230 million years. This small two-legged animal rider from the late Triassic some similarities with his contemporary the Eoraptor, but also has significant differences that provide insight into early evolution of dinosaurs, then still relatively unknown.
After comparing the two animals, Ricardo Martinez of the Universidad
Nacional de San Juan in Argentina, and colleagues came to the conclusion
that the early Eodramaeus was an ancestor of the lineage of theropod
dinosaurs that includes predators. And Eoraptor, generally regarded as a
theropod is actually an ancestor of the early lineage of sauropods that
includes the giant long-necked herbivores. Eodramaeus had a skull with
more characters like theropod, such as opening near the tip of his nose
called the window promaxillaire and other features "derivatives "in the
trunk pelvis and limbs, the authors write. Eoraptor was not only devoid
of these characters but had more features like sauropod whose nostrils
expanded, and a first lower tooth.
Both species, however, measured less than two meters and ran on their
two legs, the similarities suggest that the three major clades of
dinosaurs ornithischians the sauropodomorphs and theropods, shared an
outline of the body at the end of the Triassic, before that the
dinosaurs reigned supreme in the early Jurassic. The fossils were
discovered in Eodramaeus training Ischigualasto in north-eastern
Argentina, a region that has provided other important fossils of
dinosaurs. In their article, the authors also analyzed and dated this
formation marks diversity among dinosaurs and other herbivores. It shows
that dinosaurs were more diverse and common in the early Triassic than
previously thought for this region. In addition, the first dinosaurs do
not seem to have much more diverse when other herbivores disappeared,
suggesting that their rise has not resulted in the immediate replacement
of niches abandoned as suggested by a hypothesis.
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Last Updated ( Monday, 17 January 2011 )
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