Science: Even more evidence

Posted: December 18, 2008 in Evolution, News
Tags: , , , ,

r325027_1454894Time and again science makes huge strides forwards, making discovery after discovery and generally making life better for humankind in innumerable ways.  Over the past few days, there have been three separate stories all about more progress science has made including uncovering yet more (as if more were actually needed but it is kind of nice) evidence to support existing scientific theories.  We have new fossils from Argentina, more fossils from the Sahara Desert and finally more discoveries about what may have killed off the dinosaurs.

Giant Austroraptor discovered in Argentina

The fossils of a newly discovered, meat-eating raptor dinosaur, one of the biggest and perhaps most recent to live in Argentina’s Patagonia region 70 million years ago, have been presented at a Buenos Aires museum.

The fossils of the dinosaur named “Austroraptor cabazai” were found at Bajo de Santa Rosa, in Rio Negro province, which has already yielded several species of herbivore dinosaurs, during paleontological digs funded by the US National Geographic Society.

Measuring five metres in length with a long, flat cranium, short forearms, and jaws full of sharp teeth, Austroraptor was among the largest of the raptors, and belonged to the dromaeosaurids or birdlike dinosaurs that walked on two legs, the most famous of which was the Velociraptor mongoliensis.

The Austroraptor was found in rock formations dating to 70 million years’ ago, making it one of the last dinosaurs to walk in Patagonia before they became extinct at the end of the Cretaceous period 145 to 65 million years’ ago.

A plastic reproduction of the Austroraptor cabazai skeleton will be included in an exhibit of Argentine dinosaurs to open next year in Europe.

The National Geographic expedition that discovered the fossils was led by palaeontologist Fernando Novas, who made the presentation at Argentina’s Bernardino Rivadavia Museum of Natural History, in Buenos Aires.

New dinosaurs discovered by British scientists in Sahara desert

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.

Massive Volcanic Eruptions Could Have Killed Off the Dinosaurs

Huge volcanic eruptions that belched sulfur into the air for around 10,000 years could have killed the dinosaurs, according to new evidence unearthed by geologists.

Evidence is accumulating that it wasn’t an asteroid that did the beasts in, but volcanoes — the first real challenge the extinction theory has met in three decades.

A combination of studies on dinosaur fossils, magnetic signatures in rocks and the timing of the disappearance of different species suggest it was volcanoes, not an asteroid, that caused the dinosaurs’ extinction.

“We’re discovering … amazingly large flows, amazingly short time scales and amazing volcanic (eruptions),” said Vincent Courtillot of the University of Paris, who is is presenting new evidence for the volcano theory this week at the American Geophysical Union conference here.

For the last 30 years, the prevailing theory has been that an asteroid, around six miles across, hit the Yucatan peninsula 65 million years ago, throwing debris into the atmosphere, blocking the sun and chilling the planet to the point that nearly half of all species went extinct.

Physicist Luis Alvarez of the University of California, Berkeley, first presented the asteroid impact hypothesis in 1980. It was based on an extensive layer of iridium, which is associated with impacts, that could be found in many places across the globe in the same geologic time sequence. A decade later, the Chicxulub crater was discovered on the Yucatan peninsula, adding weight to the idea that an impact killed off the dinosaurs.

The idea that Indian volcanoes, known as the Deccan Traps, might have contributed to the mass extinction is not new. But scientists at the AGU meeting think the eruptions could be the sole cause of the die-offs, and that the asteroid had little or no effect on life at all.

“If there had been no impact, we think there would have been a massive extinction anyway,” Courtillot said.

Courtillot has studied the magnetic signatures of the Indian volcanic deposits that lined up with the Earth’s magnetic field as they cooled. Because the orientation of the magnetic field has changed over time, lava that cooled at different times have different signatures.

The more than 2-mile thick pile of Deccan Traps deposits has several major pulses that occurred over the course of several decades each, almost certainly less than 100 years. And the entire sequence erupted in less than 10,000 years, rather than the million years or more that has been suggested.

All told, this would have put 10 times more climate-changing emissions into the atmosphere than the asteroid impact.

Also supporting the volcanic theory is fossil evidence from Texas and Mexico that most of the species extinctions coincided with the final pulse of eruptions, not with the asteroid impact, which may have occurred approximately 300,000 years earlier, according to Gerta Keller of Princeton University.

“There is essentially no extinction associated with the impact,” Keller said.

Evidence that dinosaurs survived in India right up to the final volcanic onslaught further bolsters the case.

But it will take a lot of evidence to convince the bulk of the scientific community that the asteroid theory is wrong.

“There was volcanism at the time. There’s always volcanism, but that impact is so significant that you can’t ignore it,” said Rick Firestone of Lawrence Berkeley National Laboratory who studies the link between impacts and extinctions. “The only question is, were there other things that happened as result of it.”

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Comments
  1. ozatheist says:

    I just love fossils, it’s so interesting to read about these sorts of finds. It still amazes me that these beasts lived all those years ago. It’s such an amazing planet this one.

    I have a question on dinosaurs. When is the first record of a dinosaur being found?

    reason I ask is because some while back I was reading a site (forgot to bookmark it. doh) which talked about the ancient Greeks investigating (or philosophising as they used to call it) dinosaur bones. The site went on to hypothesise that fossils may have been where tales of dragons, unicorns and other mythical beasts came from. The theory being that as far back as man has been around they would of have to have found fossils and they wouldn’t have been able to work out what sort of beast the bones came from, and thus guessed (wrongly mostly).

    Ever heard of this idea? What do you think?

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