Sunday, December 03, 2006

 

Nevada dinosaur fossils unveiled

Las Vegas - Nevada's state fossil, the giant ocean-roaming fish-reptile known as the ichthyosaur, will have to share the scientific stage after researchers this week unveiled the first fossils of land-based dinosaurs ever found in Nevada.

The discovery expands the known range of the prehistoric beasts and offers a new understanding of life in the state some 100 million years ago.

Put on display for the first time Thursday were the femur of the raptor, dromaeosaur, the teeth of a sauropod, a tyrannosauroid and an iguanodont and unidentified dinosaur eggshell fragments.

Continued at "Nevada dinosaur fossils unveiled"
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Info on The Dromaeosauridae from the University of California Museum of Paleontology:

Dromaeosaurs constitute a small clade of theropod dinosaurs which exhibit some highly derived characteristics that they all share, especially modifications of the forelimb allowing for a flexible seizing function (which is thought to have been modified to create the bird "flight stroke"). According to current thinking, birds are hypothesized to have shared a common ancestor with the dromaeosaurs sometime in the Jurassic period; Dromaeosauridae is thus termed the sister group of the clade Aves (which includes all birds). It may even be that the ancestry of birds lies within this group, which would make them dromaeosaurs too, but this is not at all established. [More]
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Info on The Sauropod Dinosaurs from UMCP:

Sauropods are a subgroup of the saurischian, or "lizard-hipped," dinosaurs. This group of quadrupedal (four-legged), herbivorous animals had a relatively simple body plan which varied only slightly throughout the group. Early relatives of the sauropods, the Late Triassic plateosaurs or prosauropods, may have occasionally stood on their hind legs. True sauropods, such as Diplodocus shown here, appeared in the Late Triassic and began to diversify in the Middle Jurassic, about 180 million years ago. [More]

Info on Tyrannosaurus from Cornell:

King of the Cretaceous, Tyrannosaurus rex stood on two powerful hind limbs and terrorized potential prey with its elephantine size and lethal jaws. The dinosaur was big and bad. But was it fast?

That's long been a topic of scientific debate, with some paleontologists arguing T. rex ran at a zippy top speed of 45 miles per hour and others suggesting a more moderate 25 miles per hour. Both estimates seemed fast to John Hutchinson of Stanford, who as a graduate student at the University of California-Berkeley set out with help from postdoctoral researcher Mariano Garcia, now of Borg-Warner Automotive, to test them using principles of biomechanics.

The researchers created a computer model to calculate how much leg muscle a land animal would need to support running fast. In the February 28 (2002) issue of the journal Nature, they report that T. rex probably could not run quickly. In fact, hindered by its size, it may not have been able to run at all. Though not enough is known to give an exact speed limit for T. rex, a range of 10 to 25 miles per hour is possible, according to the authors. [More]

Info on Iguanodons

Iguanodon (meaning "Iguana tooth") is the name given to a genus of ornithopod dinosaurs, which lived roughly halfway between the early hypsilophodontids and their ultimate culmination in the duck-billed dinosaurs. They lived between 120 to 140 million years ago, in the Barremian to Valanginian ages of the Early Cretaceous Period, although one dubious species is from the Late Jurassic. Iguanodon's most distinctive feature was a large razor-sharp 'thumb spike', probably used for defense against predators.

Iguanodon was the first dinosaur recognized and the second dinosaur formally named, described in 1822 by English geologist Gideon Mantell. Together with Megalosaurus and Hylaeosaurus, it was one of the three originally used to define the new classification, Dinosauria. [More]
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