From: Andy Soos, ENN
Published February 25, 2013 04:55 PM

Why Long Necked Dinosaurs

Dinosaurs often are depicted with very long necks. Nowadays we have the giraffe with a long neck who seem to have evolved this feature due to the need to eat leaves higher up. So why and how the dinosaur with its long neck? Researchers say the how is helped by hollow neck bones. The largest creatures to ever walk the Earth were the long-necked, long-tailed dinosaurs known as the sauropods. These vegetarians had by far the longest necks of any known animal. The dinosaurs' necks reached up to 50 feet  in length, six times longer than that of the current world-record holder, the giraffe, and at least five times longer than those of any other animal that has lived on land.

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Several anatomical features enabled this extreme dinosaur elongation, including:  absolutely large body size and quadrupedal stance providing a stable platform for a long neck; a small, light head that did not orally process food; cervical vertebrae that were both numerous and individually elongate; an efficient air-sac-based respiratory system; and distinctive cervical architecture. 

"They were really stupidly, absurdly oversized," said researcher Michael Taylor, a vertebrate paleontologist at the University of Bristol in England. "In our feeble, modern world, we're used to thinking of elephants as big, but sauropods reached 10 times the size elephants do. They were the size of walking whales."

Among living animals, adult bull giraffes have the longest necks, capable of reaching about 8 feet long. The giraffe is an African even-toed ungulate mammal, the tallest living terrestrial animal and the largest ruminant. Its chief distinguishing characteristics are its extremely long neck and legs and its distinctive coat patterns. It stands 16—20 feet tall and has an average weight of 3,500 pounds.  

When it comes to extinct animals, the largest land-living mammal of all time was the rhino-like creature Paraceratherium, which had a neck maybe 8.2 feet. The flying reptiles known as pterosaurs could also have surprisingly long necks, such as Arambourgiania, whose neck may have exceeded 10 feet.

As to why sauropods evolved such long necks, there are currently three theories. Some of the dinosaurs may have used their long necks to feed on high leaves, like giraffes do. Others may have used their necks to graze on large swaths of vegetation by sweeping the ground side to side like geese do. This helped them make the most out of every step, which would be a big deal for such heavy creatures.

Scientists have also suggested that long necks may have been sexually attractive, therefore driving the evolution of ever-longer necks; however, Taylor and his colleagues have found no evidence this was the case.

For further information see Long Necks.

Dinosaur image via Wikipedia.

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