Dinosaurs got big by taking it easy

Some dinosaurs grew larger than today's elephants because they ate more and used less energy, says a US scientist.

The study, which appears this week in Proceedings of the National Academy of Science, 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, writes 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.

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