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TOPIC: Dinosaurs


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Turiasaurus riodevensis
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The fossil bones of what may have been Europe's largest animal ever, a new type of dinosaur, have been discovered in Spain.
Discovery of the sauropod, estimated to have weighed between 40 and 48 tons, is reported in Friday's issue of the journal Science.
Named Turiasaurus riodevensis, the animal lived in the Teruel area of what is now Spain in the late Jurassic period, about 150 million years ago.
The remains were found by a team led by Rafael Royo-Torres of the Joint Palaeontology Foundation Teruel-Dinopolis.
In the past such large dinosaurs have primarily been found in Africa and the New World.

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Dinosaurs -- stones did not help with digestion
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Sauropods did not have a 'gastric mill.' How they processed their food without molars remains unclear
The giant dinosaurs had a problem. Many of them had narrow, pointed teeth, which were more suited to tearing off plants rather than chewing them. But how did they then grind their food? Until recently many researchers have assumed that they were helped by stones which they swallowed. In their muscular stomach these then acted as a kind of 'gastric mill'.
But this assumption does not seem to be correct, as scientists at the universities of Bonn and Tübingen have now proved. Their research findings can be found in the current issue of the journal Proceedings of the Royal Society (doi:10.1098/rspb.2006.3763).
What do you do if you do not have good teeth, and food is hard to digest? Some herbivorous birds which have a toothless beak, such as ostriches, solve the problem with what is known as a gastric mill. Their muscular stomach is equipped with a layer of horn and contains stones which help to break up, crush and thereby also to digest food.
Giant dinosaurs from the Jurassic and Cretaceous period (200 million to 65 million years ago) such as Seismosaurus and Cedarosaurus must have had similar digestive problems. The animals, some of which weighed more than 30 tonnes, were the largest herbivores which have ever existed. Many of them had a very small head, in relation to the size of their body, and narrow, pointed teeth, which were more suited to tearing off plants rather than chewing them. At the same time, they had to digest enormous amounts of food for their rapid growth and the metabolism of their gigantic bodies. Smoothly polished stones, which were found in several cases at excavations involving skeletons of sauropods, are also interpreted as gastric stones.
However, Dr. Oliver Wings from the Institute of Earth Sciences at the University of Tübingen, and Dr. Martin Sander from the University of Bonn have shown that this cannot at least be a gastric mill such as birds, today's relatives of the dinosaurs possess. Among these the ostrich is the largest herbivore. For their investigations, the scientists therefore offered stones such as limestone, rose quartz and granite as food to ostriches on a German ostrich farm.
After the ostriches had been slaughtered, the scientists investigated the gastric stones. It became clear that they wore out quickly in the muscular stomach and were not polished. On the contrary, the surface of the stones, which had been partly smooth, became rough in the stomachs during the experiments. The mass of the stones then corresponded on average to one per cent of the body mass of the birds.

'Whereas occasionally stones were found together with sauropod skeletons, we don't think they are remains of a gastric mill such as occurs in birds' - Dr. Martin Sander.

In that kind of gastric mill the stones would have been very worn and would not have a smoothly polished surface. Apart from that, gastric stones are not discovered regularly at sauropod sites. When present, their mass is, in relation to the body size, much less than with birds.

'In comparing these we extrapolate over four orders of magnitude, from an ostrich weighing 89 kilograms to a sauropod weighing 50,000 kilograms. This may seem a bit daring. However, within birds the range of body weight and corresponding masses of gastric stones also spans four orders of magnitude, from the 17 gram robin to the ostrich' - Dr. Oliver Wings, who moved from Bonn University to Tübingen only recently.

Yet what else were the dinosaurs' gastric stones used for? The researchers presume that they were accidentally eaten with their food or could have been swallowed on purpose to improve the intake of minerals. But if the stones did not help to crush vegetable food, the sauropods' digestive system must have used other methods, since the decomposition of large amounts of material which is difficult to digest requires the assistance of bacteria in the digestive system. The smaller the pieces are, the better they can break down the food. Possibly, the scientists conclude, the intestines of the sauropods were formed in such a way that the food was retained there for a very long time, in order to improve the digestive process.
There is another group of dinosaurs, however, whose remains of gastric stones can be linked up with a birdlike gastric mill, according to Oliver Wings' research. From these dinosaurs known as theropods today's birds developed. The gastric mill could therefore have developed in the ancestral line of birds.

Source University of Bonn

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Nevada's Dinosaurs
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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.
The remnants, found at secret excavation sites in southern Nevada, pushed the known range of the ancient reptiles about 250 miles farther west. The area is believed to have once been a flood plain where the creatures lived and died for many generations from 99 million to 112 million years ago.

"Most of these groups of dinosaurs are known from other places in the United States. What we're able to do is push the ranges of these animals all the way up to Nevada now, where previously the farthest west they've been is east-central Utah" - Joshua Bonde, a graduate earth science student at Montana State University who is leading the dig.

The find was presented in a tent on the site of a future state museum where they will be housed.

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Edmontosaurus annectens
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Edmontosaurus annectens
Researchers from the North Carolina Museum of Natural Sciences and North Carolina State University announced the results of their first palaeontology fieldwork collaboration. The find? A remarkably complete skeleton and skin impressions from a 67-million-year-old duckbilled dinosaur (Edmontosaurus annectens). The specimen, painstakingly recovered from a Montana hillside this past summer, is the most complete dinosaur ever brought to the state of North Carolina and estimated to be in the top five percent of all dinosaur specimens worldwide, in terms of completeness and preservation.

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RE: Dinosaurs
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Hanging out with emus might seem an odd way to gain a new understanding of dinosaur behaviour, but it has yielded valuable insight for a Wyoming palaeontologist studying the Red Gulch Tracksite.
Brent Breithaupt, director of the University of Wyoming Geological Museum in Laramie, has been using the large, flightless emu as a modern-day proxy in learning how dinosaurs laid down tracks near here 165 million years ago.
Breithaupt and other researchers have spent years collecting data on more than 1,000 preserved dinosaur tracks at Red Gulch.

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They may have ruled the land and the seas 75 million years ago but even dinosaurs fell prey to the lowest of the low - gut worms.
An unusually well-preserved fossil of a duck-billed dinosaur dug up in Montana, in the US, has revealed great detail of the animal's insides, including what appear to be tiny burrows that would have been made by worms, the team at the University of Colorado at Boulder found.
They found more than 200 suspected parasite burrows that most likely were made by tiny worms similar to annelids and nematodes that infest animals today, said assistant geology professor Karen Chin.

"Fossil evidence for interactions between dinosaurs and invertebrates usually involves insects. This research is exciting because it provides evidence for the movement of tiny, soft-bodied organisms inside the gut cavity of a dinosaur" - Karen Chin.

Prof Chin and graduate student Justin Tweet are presenting their findings to a meeting in Philadelphia of the Geological Society of America.

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Dinosaur tracks
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The mysterious moves of two-footed Jurassic dinosaurs traveling along a long-lost beach have been brought to life with emus.
Unlike computer models that have been developed to simulate the gait, and therefore the possible trackways of specific dinosaurs, live emus allow for direct comparisons of complex tracks to specific behaviours, say researchers looking at the thousands of tracks left behind 165 million years ago by dinosaurs at Red Gulch in northern Wyoming.

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RE: Dinosaurs
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It is often stated in the palaeontological literature that the chance an animal will become fossilised is "one in a million." This number is meant to be taken figuratively, the point being that the odds of surviving the rigors of deep time are extremely remote. Nevertheless, all field palaeontologists know that the earth is biased when it comes to giving up its dead--the odds of an animal being preserved and consequently exhumed are much greater in some settings than others.

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One recent week in the Gobi Desert produced 67 dinosaur skeletons for a team of palaeontologists from Montana and Mongolia who want to flesh out the developmental biology of dinosaurs.

Montana State University palaeontologist Jack Horner said Wednesday that the same area yielded 30 skeletons last year, so researchers at MSU and Mongolia's Science and Technology University now have about 100 Psittacosaurus skeletons. The skeletons ranged in length from one to five feet and stood about two feet tall.

"That's what I was there for -- getting as many of those as we could possibly get" - Jack Horner .

He was specifically looking for Psittacosaurus fossils because it was a very common dinosaur and would give him lots of specimens, Horner said. It would also keep away poachers and commercial fossil hunters who work in the area, but prefer rare fossils. Horner wants a large number of fossils so he can compare variations between skeletons and changes during growth.

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To paraphrase Shakespeare: there are more dinosaurs in earth and rock than dreamt of by modern palaeontology. Revising an earlier estimate based on discoveries to date, anatomist Peter Dodson of the University of Pennsylvania and statistician Steve Wang of Swarthmore College predict that 71 percent of dinosaur genera--the organizational grouping into which individual species fall--still remain to be discovered.

"It's a safe bet that a child born today could expect a very fruitful career in dinosaur palaeontology" - Peter Dodson.

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Dodson first estimated the potential number of dinosaur genera in 1990 and now is revising that upward.

The estimates are based on the rates of discovery - about 10 to 20 annually - and the recent increase in finds of fossils in China, Mongolia and South America.
Dodson suggests that 1,850 genera will eventually be discovered. So far 527 genera have been found.
Fossilisation itself is a rare event, they note, and as many as half of the dinosaur genera that ever existed may have left no remains.

-- Edited by Blobrana at 08:22, 2006-09-05

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