SCIENCES – This dinosaur lived there 95 million years …
spinosaurus, a strange behemoth weighing up to twenty tons, a sort of cross between a duck and an alligator, was the first dinosaur unearthed which has anatomical features of an adaptation to a semi-aquatic environment, according to fossils found in Morocco.
Long and 15m and with a twenty sharp teeth in a long narrow snout, this dinosaur already known to be carnivorous and lived there about 95 million years ago, also devoured fish.
The first bones of spinosaurus had been in Egypt in 1912 and described in 1915 by German palaeontologist Ernst Stromer von Reichenbach, but it was not detected when the capabilities of aquatic adaptation of the animal.
surpassed spinosaurus widely in size the famous Tyrannosaurus Rex (T-Rex), who lived in North America several million years after the disappearance of spinosaurus, say the scientists whose discovery was published Thursday in the journal Science.
The largest known predator
According to the international team of researchers, the spinosaurus is the largest known predatory dinosaur that lived on the planet, exceeding three meters in length the largest specimen of T-Rex ever discovered.
The most complete fossil of a spinosaurus skeleton to date clearly he could move both on land and in water shows, explains Paul Sereno and Nizar Ibrahim, paleontologists from the University of Chicago (Illinois, North), the main co-authors of this discovery.
The bones, parts of the skull, spine, pelvis and limbs, were discovered during several years in freshwater sediments in the Moroccan Sahara, south-east of the country.
They provide clear indications that this animal lived partly in an aquatic environment, making it the first known dinosaur able to swim, say the scientists.
marine reptiles like plesiosaurs and mosasaurs were not dinosaurs, though they have some similarities, they specify .
Muzzle crocodile
Among the features of aquatic adaptation observed in the bones of the spinosaurus, the researchers covered the presence of a nostril on the top of the head to avoid that water enters, relatively long forelimbs and large webbed feet flat to swim, but also to walk on muddy soil or mud.
They also report a high density Bone members that would have allowed this dinosaur to stay immersed in water rather than floating.
This bone density reminiscent of the first whales and hippos today, notes the anatomist JGM Thewissen, the Northeast Ohio Medical University, quoted in the journal Science.
For the paleontologist Paul Sereno, “the spinosaurus with its snout of a crocodile, his long neck and elongated body should look like a duck with an alligator tail. “
He also noted during a press conference that this dinosaur would have great difficulty on the ground to keep his balance for a long time on its hind legs saw his anatomy.
According to these researchers, the huge ridge on its back, reminiscent of a sail, was mostly used to seduce its reproduction rather than help it swim.
waiting a century
fossils discovered in 1912 were destroyed when they were in the Natural History Museum in Munich with other paleontology collections in April 1944 during of Allied bombing of the city.
He had to wait nearly a century to have a new skeleton spinosaurus, the first bones were first discovered by a nomadic amateur fossil collector Morocco.
Luckily, notes, drawings and publications of Ernest Stromer, who were in the family castle in Bavaria, survived and helped make detailed with the bones discovered in Morocco comparisons.
To reconstruct the image of a more complete skeleton of spinosaurus, scientists have combined the information from the new fossils and digital versions of the bones described by Ernest Stromer, as well as an ancestor of this dinosaur, the Suchomimus, which was however very different.
This discovery will also be an exhibition in the National Geographic Museum in Washington as well as an article in the October issue of the famous magazine.
20 Minutes with AFP
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