Osteoderms storing minerals helped huge dinosaurs survive

Huge dinosaurs stored vital minerals in bones under their skin (osteoderms) to help them survive, a study has found. These 'skin bones' helped some of the biggest dinosaurs survive in lean times and bear their young, say North American scientists.

Long-necked sauropod plant-eating dinosaurs used osteoderms, or 'skin bones' to store minerals, according to a study published in the journal, Nature Communications.

The sediment record around adult and junior dinosaur fossils in Madagascar shows how they battled periodic drought and a semi-arid landscape.

Co-author of the report is Matthew Vickaryous, a biomedical scientist from the University of Guelph, in Canada.

He says, "Our findings suggest that osteoderms provided an internal source of calcium and phosphorus when environmental and physiological conditions were stressful."

Matthew Vickaryous helped interpret the results of fossilized tissue cores and CT scans of the dinosaurs.

He studies how skeletons grow and evolve as part of his work as a researcher in the Department of Biomedical Sciences at Ontario Veterinary College. Also working on the study were geologist Raymond Rogers and palaeontologist Kristina Curry Rogers, from Macalaster College, Minnesota, and palaeontologist Michael D'Emic, who is now at Georgia Southern University.

The osteoderm bones, which were the largest of their kind ever found, were shaped like rugby balls cut lengthways. The adult bones were as big as sports bags and were hollow, suggesting they had been remodelled.

They were common in well-protected dinosaurs, such as stegosaurs and ankylosaurs that had tail clubs. Nowadays, they are seen in alligators and armadillos.

Osteoderms are rare among sauropod dinosaurs and have only been found in huge, long-necked plant-eating dinosaurs, called titanosaurs.

Female titanosaurs laid many volleyball-sized eggs in the same way that crocodiles and alligators today lay dozens of eggs and absorb minerals from their bones.

The bones of the young dinosaur were solid, which shows that osteoderms were used to store minerals in older animals.