Washington, Oct 10 : A new research has suggested that dinosaurs known as sauropods, which were the largest land animals that ever lived, grew huge and were an evolutionary success in part because they didn't bother to chew their food.
Sauropods weighed up to 88 tons (80 metric tons)-ten times more than an African elephant-and measured as high as 23 feet (7 meters).
The group of dinosaurs, which included the brachiosaurus and diplodocus, loomed over the animal kingdom for more than 140 million years until the late Cretaceous period, 65 million years ago.
Scientists think the animals evolved to be so large to discourage big predators, like Tyrannosaurus rex, from eating them. But how they maintained such massive body sizes has remained mysterious.
The herbivores, or plant-eaters, had hardly any teeth and are thought to have swallowed their food whole. They browsed large areas, barely moving and consuming vast quantities in short periods of time.
So, they needed long necks to reach food high in trees and a huge gut to process and break down their unchewed meals, Martin Sander, a palaeontologist at the University of Bonn in Germany and co-author of the study told National Geographic News. "You can only have this long neck if you don't chew your food, otherwise your head would be full of teeth and too heavy to support," he said.
Paul Upchurch, an expert on sauropods from University College London, said that "most palaeontologists agree that feeding is the key to understanding sauropod gigantism."
To outgrow their predators, sauropods didn't just need lots of food. They also needed to develop fast, so they could attain their full size before being eaten, experts said.
Sauropod bones show that they did indeed grow swiftly. A 22-pound (10-kilogram) hatchling could become a 220,000-pound (100,000-kilogram) grown-up in about 20 to 30 years-quick by dinosaur time.
"This tells us that they must have been warm-blooded and had a high metabolic rate compared to cold-blooded creatures," said Sander.