Scientists have long wondered how an extinct goat that once lived on barren Mediterranean islands could survive in such a harsh environment. Now they know: In a first-of-its-kind trick for the mammal kingdom, this goat lived like a lizard.

Myotragus balearicus skeletons were made from lamellar-zonal bone, which is textured like the growth rings of trees, according to a fossil analysis published Monday in the Proceedings of the National Academy of Science. It's found only in creatures that can't regulate their body temperature internally, such as amphibians and reptiles.

These animals slow their metabolism when food is scarce or temperatures are cold, and speed up during times of plenty. The presence of this pattern in Myotragus suggests that the goat "grew unlike any other mammal but similar to crocodiles at slow and flexible rates," wrote the study's authors.

The odd goat's on-the-fly metabolic adjustment was probably an evolutionary leftover from when mammals first split from dinosaurs, and hadn't yet developed the relatively steady, fast-paced metabolic rates they now possess.

Myotragus also had an extremely tiny, energy-efficient brain. For most of the last 6 million years, these adaptations made it well-suited for existence on the arid, nutrient-starved islands of Majorca and Minorca, where it had no predators. But they were also the downfall: When humans arrived on the islands 5,000 years ago, they had no trouble hunting the sluggish goat to extinction.

Images: 1) A Myotragus reconstruction/Wikipedia. 2) Myotragus' *lamellar-zonal tissue structure/*PNAS.

See Also:

Citation: "Physiological and life history strategies of a fossil large mammal in a resource-limited environment." By Meike Kohler and Salvador Moya. Proceedings of the National Academy of Sciences, Vol. 106, No. 46, Nov. 16, 2009.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecosystem and planetary tipping points.