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What is a dinosaur? & when did they live??

What is a dinosaur? & when did they live??

Monday, 6 June 2011

Plesiosauria

Plesiosauria includes the large, carnivorous, marine reptiles the Plesiosaurs and Pliosaurs. They used their flippers to propel themselves through the water, rather like a turtle except that they used both the front and rear flippers. Scientists were intrigued to find that using all four flippers didn't make them faster. In fact, the opposite was true, as turbulence from the front flippers interfered with the efficiency of the rear flippers. However, four flippers did make it easier to get going and brake. So while Plesiosaurs and Pliosaurs may not have been ultra-speedy, they would have been agile and quick to react to passing prey.

Neanderthal

Neanderthal

Neanderthals looked much like modern humans only shorter, more heavily built and much stronger, particularly in the arms and hands. Their skulls show that they had no chin and their foreheads sloped backwards. The brain case was lower but longer housing a slightly larger brain than that of modern humans. As almost exclusively carnivorous, both male and female Neanderthals hunted. Evidence of a huge number of injuries - like those sometimes seen in today's rodeo riders - suggests that hunting involved dangerously close contact with large prey animals.
Scientific name: Homo neanderthalensis
Rank: Species

Common names:

 
Man of the Neander Valley



Saturday, 4 June 2011

Tundra
Tundra is the cold, treeless region around the poles that has permafrost as one of its defining features. Even at the height of summer, the soil a few centimetres under the surface remains frozen. The tundra therefore lacks animals that dig deep burrows and plants that require deep root systems. The permafrost, plus the short summer and seasonal waterlogging, also explains why trees don't grow here.