Sydney, July 9 (ANI): A US scientist has said that some dinosaurs grew larger than today's elephants because they ate more and used less energy.
According to a report in ABC Science, the study suggests two factors, energy expenditure and food intake, influence the size of animals.
Using a mathematical model, study author Dr Brian McNab of the University of Florida, determined that animals that expend more energy and have a faster metabolism, which is typically linked to temperature regulation, have a smaller body mass.
Fast metabolism is a characteristic of large warm blooded animals. They use food to generate heat and maintain a constant body temperature, he writes.
Cold blooded animals, like most reptiles, have a slow metabolism and rely on the environment for body warmth.
McNab has proposed that, rather than use all their energy to maintain body temperature the way warm-blooded animals do, large dinosaurs used their energy to grow.
Large present-day mammals, like the African elephant, haven't reached sizes similar to dinosaurs because they use most of their energy on temperature regulation, he added.
McNab said that due to their size, large dinosaurs were able to maintain a constant body temperature through thermal inertia and a small surface-to-volume ratio.
As a result, McNab concludes that dinosaurs like sauropods were homeothermic - had an intermediate body temperature.
Palaeontologist Dr John Long, of Museum Victoria, said that the idea that dinosaurs had intermediate body temperatures is not unusual.
He said that some large cold blooded animals can maintain a constant body temperature regardless of the environment - much like warm blooded animals.
"If you think of the giant turtles that live in the cold waters of the Atlantic they can have much higher body temperatures than the sea water around them," said Long.
He said that the bigger an animal is, the less energy it takes to maintain a constant and higher body temperature.
"They can generate heat through their muscle metabolism," he said. (ANI)