Some hundred million years ago, crocodiles were the ruling T. rexes of the waters. They galloped on land, ambushed prey at the river's edge ... even terrorized dinosaurs. And more, these swift predators' cousins evolved through the ages into the modern crocs we know today. Now, armed with newly discovered prehistoric crocodile bones, Explorer-in-Residence Dr. Paul Sereno is determined to bring the ancient creatures to life - and tell their fantastic untold story. Learn about a croc that pursued prey across land, a supercroc that locked its jaws around dinos, and even one with a startlingly canine face. Blending art, forensics and biology, Sereno's team recreates a lost world of strange Cretaceous crocs that paleontology forgot.

Mark Witton estimated that the pterosaur had a wingspan of 16.4ft (5m) and would have been more than 39in (1m) tall at the shoulder.

The partial skull fossil, found in Brazil, is the first example of a chaoyangopteridae, a group of toothless pterosaurs, to be found outside China.

Mr Witton said: "Some of the previous examples we have from this family in China are just 60cm (2ft) long - as big as the skull of the new species.

"Put simply, it dwarfs any chaoyangopterid we've seen before by miles."

Researchers had thought that frozen cells were unusable because ice crystals would have damaged the DNA. That belief would rule out the possibility of resurrecting extinct animals from their frozen remains.

But the latest research -- published in the journal, Proceedings for the National Academy of Sciences -- shows that scientists may have overcome the obstacle.

Researchers at the Riken Center for Developmental Biology in Kobe, Japan, used cells from mice that had been frozen for 16 years at -20 Celsius (-4 degrees Fahrenheit).

They extracted the nucleus and injected it into eggs whose DNA had been removed. Several steps later, the scientists were able to clone the mice.

Without any ballyhoo, the museum launched a new attraction in June called Dinosaur Encounters, in which actor-puppeteers don lifelike T. rex or triceratops suits and spend 20 minutes demonstrating how scientists believe baby dinos behaved. Usually they work with interpreter-handlers, but sometimes they just roam free and meet their public. Which is how a museum-goer's video of a grunting, bemused, 7-foot-tall and 14-foot-long T. rex inspecting babes-in-arms and other humans at close range came to be posted on MySpacetv on Thursday. "Real Live Dinosaur" shot to No. 1 on MySpace's daily video chart, attracting more than 215,000 viewers by early evening -- far outstripping "Cindy and Heidi Bare It All." That clip from TMZ featured stills of Crawford and Klum yachting au naturel, their modesty preserved by strategically placed black bars.

A new study of the extinct creature's skull shows it had an almighty bite, making the prehistoric fish one of the most fearsome predators of all time.

All the more remarkable, scientists say, because the crushing force came from jaws made of cartilage, not bone.

The researchers report their skull work in the Journal of Zoology.

The megalodon super-shark swam in the oceans more than a million-and-a-half years ago.

It grew up to 16m (52ft) in length and weighed in at 100 tonnes - 30 times heavier than the largest great white - and must have been one of the most formidable carnivores to have existed.

The extinct creature, Dunkleosteus terrelli, could bring its jaws together with a remarkable force of 5,000 Newtons (1,100lbs-force).

This performance surpasses all living fish, including today's great white shark, and puts it up with some of the most powerful bites in all animals.

Details appear in the UK Royal Society journal Biology Letters.

US researchers Mark Westneat and Philip Anderson tell the journal that higher bite forces have only been reported for some large alligators and dinosaurs.

T. rex, for example, could clamp down on its meal with a crushing force of 13,000 Newtons (3,000lbs-force); but a modern spotted hyena, by comparison, exerts a force of only 2,000 Newtons (500lbs-force) when it cracks bones in its mouth.

"This was a very weird place," said Professor Mike Archer, who has led a team into Australia's "fossil land", a region in north west Queensland where stony remains have revealed details of the extraordinary creatures that once roamed the continent.

"None of the kangaroos - and there are about 35 different kinds of extinct 'roos in these deposits - would have looked like anything we would have recognised today," he said.

"They didn't hop. These were galloping kangaroos with big, powerful forelimbs and some had long canines like wolves.

"You might have been looking for Skippy, but you would not have seen Skippy. You would have found his ancestor who would have ended up eating you while you were looking. So it was a very strange world."

The creature, which apparently measured more than 40 feet long, is called Mapusaurus roseae. The discovery of Mapusaurus included bones from at least seven to nine of the beasts, suggesting the previously unknown animal may have lived and hunted in groups. That hunting strategy might have allowed it to attack even bigger beasts, huge plant-eating dinosaurs.

Coria noted the dig showed evidence of social behavior in Mapusaurus. The excavation found hundreds of bones from several Mapusaurus individuals but none from any other creature. That suggests the animals were together before they died, Coria said.

Perhaps they hunted in packs, though there is no direct evidence for that, he said in an e-mail. Currie, in a statement from his university, speculated that pack hunting may have allowed Mapusaurus to prey on the biggest known dinosaur, Argentinosaurus, a 125-foot-long plant-eater.

Holtz called the finding the first substantive evidence of group living by giant two-legged carnivores other than tyrannosaurs. It's not clear whether the animals cooperated in hunting, as wolves or lions do, or simply mobbed their prey or just gathered around after one of them made a kill, he said.

The discovery of a new, remarkably preserved fossil of a beaver-like mammal that lived 164 million years ago is shaking palaeontologists’ understanding of early mammals.

Looking as if it was put together from pieces of platypus, river otter, and beaver, the creature was nearly half a metre long and weighed about half a kilogram. This makes it the largest mammal ever found in the Jurassic Period, from 200 million to 145 million years ago.

The fossil of the semi-aquatic mammal Castorocauda lutrasimilis was discovered in the middle Jurassic Jiulongshan formation in Inner Mongolia, China, by Qiang Ji at Nanjing University, and colleagues. It boasts the oldest fossil fur ever found.

Palaeontologists had long thought the mammals living under the feet of the dinosaurs were tiny shrew-like animals. But recent discoveries have challenged this notion.

"Considering that Guanlong is a tyrannosaur, its crest is really amazing," Xu told New Scientist. "In this regard, Guanlong's exaggerated, complex crest is similar to the sexually selected ornaments widely present in extant and extinct vertebrates."

The near-complete fossils reveal an unusual combination of primitive features retained from ancestral dinosaurs and derived features that had been thought to evolve later. That means the similarities of later dinosaurs may show evolution converging on common traits rather than the common ancestry that palaeontologists often assume.

Tyrannosaurs grew to gianthood late in their history. "They put in the early part of their history as secondary predators," in the shadow of allosaurs and spinosaurs, says Tom Holtz of the University of Maryland in College Park, US. Nine-metre giant tyrannosaurs did not appear until about 80 million years ago, just 15 million years before an asteroid impact ended the reign of the dinosaurs.

The presence of a crest on the Guanlong adult's head was a complete surprise, Clark said, showing that there was "clearly still much more to be learned about early tyrannosaurs."

Researchers said the crest was about as thin as a pancake and only two and a half inches, or 6.4 centimeters, high. It appeared to be filled with air sacs and reminded the paleontologist of the ornamental features found on some living birds, like cassowaries and hornbills.

A newfound ancient sea creature looks to be part crocodile, part T. rex, and 100 percent terrifying.

The 13-foot long beast, Dakosaurus andiniensis, had a massive 18-inch-long jaw with interlocking 4-inch teeth. It is a long-lost relative of the crocodile yet it had fins.

"This species was very unusual, because other marine crocodiles that were around at the same time had very delicate features – long, skinny snouts and needle-like teeth for catching small fish and mollusks," said Ohio State University researcher Diego Pol, who determined the crocodile lineage. "But this croc was just the opposite. It had a short snout, and large teeth with serrated edges. It was definitely a predator of large sea creatures."

Most predatory dinosaurs such as tyrannosaurs and velociraptors have usually been depicted in museums, films and books as covered in a thick hide of dull brown or green skin. The impression was of a killer stripped of adornment in the name of hunting efficiency.

This week, however, a leading expert on dinosaur evolution will tell the British Association, the principal conference of British scientists, that this image is wrong.

Gareth Dyke, a palaeontologist of University College Dublin, will tell the BA Festival of Science being held in the city that most such creatures were coated with delicate feathery plumage that could even have been multi-coloured. Fossil evidence that such dinosaurs were feathered is now "irrefutable".

"The way these creatures are depicted can no longer be considered scientifically accurate," he said. "All the evidence is that they looked more like birds than reptiles. Tyrannosaurs might have resembled giant chicks."

It was on a fossil-hunting trip in the summer of 2000 that Leonardo's fossil was discovered. Murphy returned the following summer to excavate Leonardo, a member of the well-known species Brachylophosaurus -- a Late-Cretaceous duck-billed herbivore that grew as long as 35 feet. As his team worked on a forelimb, a volunteer saw something unusual and called to Murphy. "I took one look and said, 'Oh my God, this is skin'." When he realized he was dealing with more than a skeleton, Murphy had to revise his plan; instead of digging out the bones one by one, he had his team dig around the 23-foot-long specimen, so it could be moved to his research lab in one six-ton chunk.

Murphy hopes to transport Leonardo -- still half embedded in sedimentary rock -- to Hill Air Force Base in Utah, which has one of the world's largest CT scanners. There the heart, lung, kidneys and other organs, if they are indeed preserved inside, can be visualized and even modeled in three dimensions.

A CT scan of an entire dinosaur mummy would be an astonishing achievement, writes Adler, but no more so, perhaps, than what Mary H. Schweitzer, a biologist at North Carolina State University, accomplished with a mere fragment of T. rex bone. Schweitzer put the fossil in a weak acid and recovered a flexible substance that resembled collagen, the major organic component of bone, plus traces of red blood cells, which appear to have nuclei, holding out the possibility of recovering genetic material. And when Kent Stevens, a computer scientist at the University of Oregon, modeled on his computer the bones of the large long-necked sauropods of the late Jurassic Period, he discovered their natural position seems to lie almost parallel to the ground, or even below horizontal-an unwelcome revelation to many laymen who usually see them depicted standing foursquare with their heads high above the ground, like fat, short-legged giraffes.

One of those monsters was a seven-metre long goanna lizard (Megalania prisca). An adult would have weighed up to 600 kg. Then there were the tree-climbing crocodiles, (Trilophosuchus rackhami) nicknamed the "drop crocs" for the way they are thought to have leapt down on to their victims.

"And if that didn't get you," Professor Archer said, "there were meat-eating kangaroos that would have stood up at your shoulder and torn your arm off."