Sydney, April 1 : In a new research, a scientist has suggested that long-necked sauropod dinosaurs would had to have used far too much energy to hold their neck upright and browse tall trees.

Sauropods were about as heavy as a whale and had necks nearly five times the length of a giraffe's.

The animals have generally been reconstructed with upright necks and it was assumed they grazed on tall trees.

But, according to a report by ABC News, Dr Roger Seymour of the University of Adelaide has calculated that to do this, the dinosaurs would have needed to use 50 percent of the energy they consumed just to support their long necks.

"I think most people would agree that if you spent half of your energy pumping the blood around the body, it would be an enormous cost," said Seymour, who studies blood pressure in animals.

Seymour said that the longer an animal's neck, the higher the blood pressure it requires to pump blood to the brain.

"The giraffe's blood pressure is twice that of other mammals," he said.

While a human has a blood pressure of around 100 millimeters of mercury, a giraffe has a blood pressure of 200, according to Seymour.

He said a sauropod with an upright 9-metre neck would have had to have a blood pressure of 700.

"That is exceptionally high," said Seymour.

Seymour said that to produce such a high pressure, the sauropod would need a heart with a 2-tonne left ventricle, which would be a challenge to fit in the animal.

His most recent research has calculated that 50 percent of the energy it consumed would be used just to circulate the sauropod's blood.

"Even though they may have had access to a larger amount of food, it would have cost more than the gain, basically," said Seymour. (ANI)