An unusual fossil find in the island nation of Madagascar, off the southeastern coast of Africa, is providing scientists with new insights into the physiology of massive, long-necked, long-tailed dinosaurs known as sauropods, and how they adapted to their harsh environment.

The huge fossils unearthed by a team of U.S. and Canadian-based paleontologists are tough, hollow bones called osteoderms. The trove includes the largest such bone ever found, an adult specimen with a volume of almost 10 liters.

The scientists describe osteoderms as big, hollow bones that grow in the animal?s skin and form the distinctive armor-like plates found on many extinct and modern species of reptile.  

Among the long-necked sauropods, however, osteoderms were a rare feature, found in only one sub-group known as Titanosaurs.  These huge, lumbering plant eaters, more than 15 meters long and weighing up to 30 tons, lived about 70 million years ago, during the Late Cretaceous geological period near the end of the age of dinosaurs.

Scientists have never been sure what purpose osteoderms might have served in the lightly-armored Titanosaurs.  The U.S. and Canadian researchers speculate that these big bones would have done little to regulate body temperature or provide shielding from predators.  But they theorize that the hollow bones might have stored minerals the giant reptiles would have needed to survive in the hot, drought-prone climate of the Cretaceous.   

The paleontologists say the fossil find will also give them a more accurate idea of the Titanosaurs' physical appearance.

The Madagascar fossil discovery included the partial skeletons of two of the Titanosaurs - an adult and a juvenile.  

The researchers say this, too, is significant because the animals? age difference will indicate how osteoderms changed over the span of a lifetime.

The massive osteoderm fossil find is reported in the journal, Nature Communications.