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2008-12-17 – Sahara: nuovi resti di dinosauri (new dinosaurs)

 

Due dinosauri ritrovati nel Sahara

17 dicembre 2008
ROMA – Il dorso di un gigante rettile volante e il collo di un enorme dinosauro erbivoro sono stati recentemente ritrovati in Marocco. Il merito della scoperta è stato attribuito a due scienziati, uno inglese e l’altro irlanndese, che stavano setacciando il letto di un antico fiume prosciugato nel deserto del Sahara.

I due ricercatori hanno anche scoperto molte impronte di dinosauri ed alcuni fossili, tra i quali i resti di un coccodrillo di 18 metri e un pesce predatore. Non c’è da stupirsi, però, della presenza di resti di animali “acquatici”. Quando queste specie erano in vita, infatti, quella del Sahra era una zona prosperosa e ricca di laghi, fiumi e vegetazione. Gli scavi archeologici sono stati fatti non lontano dalla frontiera algerina, dove nel periodo Cretacico scorreva un fiume dall’ampiezza pari a quella del Danubio.

Il Dott. David Martill dell’ Università di Portsmouth ha dichiarato: “Questo sistema fluviale era pieno di pesci giganti, ognuno lungo tra i 2 e i 4 metri. Ogni cosa era enorme. Si potrebbe chiamare il fiume dei giganti”. Il ritrovamento più importante di questa spedizione, è stato il frammento di 40cm del dorso di uno pterosauro, un rettile volante che visse nel periodo dei dinosauri. Gli scienziati credono che la creatura avesse un’apertura alare di circa 6 metri e che fosse imparentato con una più grande specie esistente in Nord America.

L’altro osso ritrovato, si è ipotizzato che possa essere un frammento di gamba, forse un femore, di un dinosauro dal collo lungo. Se così dovesse essere, sarebbe quello del dinosauro più imponente mai ritrovato. Secondo Martill è un parente del brachiosauro, ma ha delle caratteristiche molto differenti. Il direttore della ricerca, Nizar Ibrahim, dell’Università di Dublino, soddisfato dell’impresa ha dichiarato: ” E’ meraviglioso pensare che milioni di anni fa il Sahara fosse un verde paradiso tropicale, dimora di dinosauri e coccodrilli, altro che il deserto che vediamo oggi”.
from: http://www.diregiovani.it/gw/producer/dettaglio.aspx?id_doc=16392

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New dinosaurs discovered by British scientists in Sahara desert

By David Derbyshire
Last updated at 3:33 PM on 17th December 2008

A prehistoric ‘river of the giants’ that was once home to gigantic fish, towering dinosaurs and 60 foot long crocodiles has been unearthed by British fossil hunters.

The river – as wide as the Danube – flowed across the Sahara desert 100 million years ago, surrounded by lush forests, waterways and lakes.

The site has yielded some of the most exciting African prehistoric finds in years – including the tip of a giant flying reptile’s beak and a limb bone from a 65 foot long plant-eating dinosaur. Both are thought to be new species.

Other finds include the remains of a crocodile the length of two double deckers, two inch long scales shed by an freshwater predatory fish, and teeth from a massive sawfish.

Rare dinosaur footprints were also found at the site, near the Algerian border in south-east Morocco.

One of the scientists, Dr David Martill, from the University of Portsmouth, said: ‘This river system was stuffed full of gigantic fishes, each 2 to 4 metres long.

‘Everything there was of a huge size. You could call it the ancient river of the giants.’

The 16 inch long beak tip belonged to a previously unknown pterosaur – a flying reptile that lived alongside the dinosaurs. Pterosaur vertebrae up to six inches long were also uncovered in the sandy rocks.

The scientists believe the creature had a wingspan of up to 20 feet and was a relative of an enormous North American species called Quetzalcoatlus, whose wings spanned nearly 50 feet.

Another major find was a three foot long bone from a giant sauropod – a plant eating dinosaur with a long neck and tail which stood on four legs.

The researchers suspect the bone is a fore-limb from a creature at least 65 feet long.

But there is an outside chance that it is the lower end of a thigh bone belonging to a dinosaur nearly 100 feet long – making it the biggest sauropod ever known.

Dr Martill said: ‘Most people have no idea how diverse sauropods were – I think nearly 100 have been described. There were lots of different families.

‘We think this one might be linked with brachiosaurus, but it is different. The bone we found has some unusual features – it’s unusually robust for a humerus. We’re 95 per cent confident that it is a humerus but if its part of a femur it would mean this creature was unimaginably enormous.

‘Plant eaters are uncommon in this deposit, extremely rare in this region and to find one this large is very exciting. It’s a major discovery.’

The finds are now being examined in detail by expedition leader Nizar Ibrahim, from University College Dublin, who is carrying out the work for his PhD.

He said: ‘It’s amazing to think that millions of years ago the Sahara was in fact a lush green tropical paradise, home to giant dinosaurs and crocodiles and nothing like the dusty desert we see today.

‘Even to a palaeontologist dealing in millions of years it gives one an overwhelming sense of deep time.’

He added: ‘Finding two specimens in one expedition is remarkable, especially as both might well represent completely new species.’

The team spent a month in the desert and travelled more than five thousand miles by Land Rover, battling sandstorms and floods.

Having discovered the giant sauropod bone they had to return to the nearest town to get more water and plaster to protect it, a trip which involved crossing flooded rivers in their Land Rover at night with water coming in through the doors.

It almost proved impossible to retrieve the heavy sauropod fossil, which had to be carried on a stretcher down the side of a mountain through pouring rain.

‘When we had managed to get the bone in the Land Rover, the extra weight meant we kept sinking in the sand dunes,’ said Dr Martill.

The team hopes to return to the region to search for more fossils in November.

Other links:


Times Online

Fossil-hunters battle Sahara storms to find dinosaur prize
Times Online – 16 dic 2008
The first fossil is the beak of a pterosaur, a giant flying reptile that lived about 100 million years ago. Such discoveries are unusual because pterosaur bones were light and fragile, to be adapted to flight, and few fossilised well.
Giant Dinosaur Fossil Found in Sahara Desert LiveScience.com
New dinosaurs discovered by British scientists in Sahara desert Mail on Sunday
Science Daily (press release) – NewsLite – Daily Mail
e altri 26 articoli simili »

dicembre 17, 2008 - Posted by | - R. Dinosauri, Africa, P - Ritrovamenti fossili, Paleontology / Paleontologia

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