A dinosaur that lived some 200 million years ago may have had eight hearts to pump blood up to its head, said scientists writing in the latest edition of the British medical journal The Lancet.

Scientists disagree over whether the herbivorous Barosaurus, some 45 feet tall, normally stood giraffe-like foraging from the tops of trees or whether it held its neck parallel to the ground.

But the report argues that the shape of the vertebrae on a reconstructed Barosaurus skeleton in New York's American Museum of Natural History suggest the former.

If so, the dinosaur would have needed an extremely powerful cardiovascular system to pump blood from its chest to its head.

Scientists from Roosevelt Hospital Center in New York believe the Barosaurus may have had a primary heart in its thorax, a secondary heart in the base of its neck and another three pairs of hearts at intervals up its 36-foot-long neck.

The immense pressure on the dinosaur's hearts from this arrangement would have predisposed it to strokes and early coronary disease, the scientists wrote. An older Barosaurus may have been prone to fainting fits if it stooped for a tasty morsel of food on the ground.

"On falling to the ground, however, it would quickly regain consciousness as the pressure differential disappeared," they wrote.