Washington, November 18 A new study has determined that a prehistoric goat on a Spanish island survived for millennia on a resource-poor island by living like a reptile, changing its growth rate and metabolism to match the available food supply.

Fossils of the ancient goat, called Myotragus, were first found on the Spanish island of Majorca in the early 1900s. The bones show the species lived on the island for more than five million years.

In most large mammals, constant high growth rates and metabolisms require continuous food supplies. By contrast, reptiles have slow growth rates and flexible metabolisms.

Since resources can fluctuate dramatically on isolated isalnds, reptiles often displace mammals in such places.

But, according to a report in National Geographic News, the new study, which looked at the bone histories of several Myotragus individuals, revealed that the goats may have fine-tuned their growth and metabolic rates both seasonally and during irregular times such as droughts-just like reptiles.

"This way, it burned only the energy that was available from the environment, slowing down the 'fire of life' in times when resources became scarce," said study co-author Meike Kohler, a paleobiologist at the Autonomous University of Barcelona, Spain.

The lizard-like lifestyle, however, meant that Myotragus's newborns were extremely small-the sizes of large rats-and the young took years to reach adult size.

The goat also saved a lot of energy in its nervous system-among the body's most "costly" tissues-by sporting a brain only half the size of a similar-size hoofed mammal and eyes only a third as large.

The combined effect was that Myotragus was sluggish, with slow reaction times, the bone study suggests.

Like modern-day reptiles, the goats probably "saved as much energy as possible just lying around and basking in the sun," Kohler said. (ANI)