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TOPIC: Ancient Marine Reptiles


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RE: Ancient Marine Reptiles
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Discovery Places Turtles Next to Lizards on Family Tree

Where do turtles belong on the evolutionary tree? For decades, the mystery has proven as tough to crack as the creatures' shells. With their body armour and retractable heads, turtles are such unique creatures that scientists have found it difficult to classify the strange animals in terms of their origins and closest relatives.
Some researchers have analysed turtles' genes and found they are most closely related to the group of animals that includes crocodiles and birds. Others, comparing turtles' physical features to those of other reptiles, have placed them next to lizards or outside of the larger subclass of animals that includes lizards, crocodiles and birds altogether.
Now Tyler Lyson, a Yale University graduate student and his colleagues have used a novel approach involving microRNAs that strongly suggests turtles belong next to lizards.

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Dorset pliosaur: 'Most fearsome predator' unveiled

A skull belonging to one of the largest "sea monsters" ever unearthed is being unveiled to the public.
The beast, which is called a pliosaur, has been described as the most fearsome predator the Earth has seen.
The fossil was found in Dorset, but it has taken 18 months to remove the skull from its rocky casing, revealing the monster in remarkable detail.

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Ichthyosaurens bitskador avslöjar slagsmål med artfrände

Scars on the jaw of a 120 million year old marine reptile suggest that life might not have been easy in the ancient polar oceans. The healed bite wounds were probably made by a member of the same species. Such injuries give important clues about the social behaviour of extinct sea creatures from the time of dinosaurs. The find is described in a forthcoming issue of Acta Palaeontologica Polonica.
Found in the remote desert near the town of Marree in northern South Australia, the fossilised skeleton belonged to an ichthyosaur, a dolphin-like marine reptile that lived during the 'Age of Dinosaurs'.
The surprising discovery of well preserved bite marks on the bones of the ichthyosaur's lower jaw were made during painstaking cleaning and reassembly of its skeleton in the laboratory. Evidence of advanced healing indicates that the animal survived the attack and lived on for some time afterwards.
The size and spacing of the tooth marks do match any potential predators or prey. Rather, they are most consistent with another adult ichthyosaur, suggesting that the wounds were inflicted during combat over food, mates or territory.

Source : Uppsala University 



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The evolution of ichthyosaurs, important marine predators of the age of dinosaurs, was hit hard by a mass extinction event 200 million years ago, according to a new study from the University of Bristol.
Ichthyosaurs originated in the Early Triassic, 250 million years ago, and during the Triassic they became hugely varied in adaptations.  Triassic ichthyosaurs ranged in length from 0.3 to 20m, and in shape from long and slender to deep-bodied.  The giant shonisaurids of the Late Triassic were whale-sized, 20m long and may have fed on shoals of squid by gulping them down with their massive mouths.
All this came to an abrupt halt at the end of the Triassic, 200 million years ago, when a mass extinction devastated life on land and in the oceans.

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The innermost secrets of a colossal "sea monster" skull are being revealed by the UK's most powerful CT scanner.
The X-rays are helping to build up a 3D picture of this ferocious predator, called a pliosaur, which terrorised the oceans 150m years ago.
The 2.4m-long fossil skull was recently unearthed along the UK's Jurassic coast, and is thought to belong to one of the biggest pliosaurs ever found.
The scans could establish if the giant is a species that is new to science.
Pliosaurs are aquatic reptiles belonging to the plesiosaur family. Paddle-like limbs would have powered their huge bulky bodies through the water, and they had enormous crocodile-like heads, packed full of razor-sharp teeth.

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Were some gigantic Jurassic sea creatures warm blooded?

In ancient Mesozoic seas, the biggest predators might not have been entirely cold-blooded killers. Rather, a new study suggests some of these rapacious reptiles might have been able to regulate their own body temperature, thereby expanding their hunting ranges. 
A new study, published online June 10 in Science, proposes that ichthyosaurs, plesiosaurs and, perhaps to a lesser extent, mosasaurs, were all able to maintain relatively stable body temperatures in tropical and frigid waters alike some 251 to 65 million years ago.

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Liopleurodon
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Skull of huge sea monster found in Dorset

The fossil has been bought for £20,000 by Dorset County Museum, and it is hoped to put it on public display there in about six months time when the rocky accretions and debris have been cleaned away.
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The fossilised skull of a colossal pliosaur - perhaps one of the biggest ever found - is unearthed on the UK's Jurassic Coast.
The ferocious predator, which is called a pliosaur, terrorised the oceans 150 million years ago.

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A gang of ancient sharks took on an enormous "sea monster" 85 million years ago, according to a new fossil analysis.
The bones of the prehistoric reptile, known as a plesiosaur, were found in Japan in 1968. But a lack of comparative samples and other resources meant that scientists didn't release a formal description of the fossil until recently.

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