Osteoderm

Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amphibians), various groups of dinosaurs (most notably ankylosaurs and stegosaurians), phytosaurs, aetosaurs, placodonts, and hupehsuchians (marine reptiles with possible ichthyosaur affinities).

Osteoderms are composed of bone tissue, and are derived from a scleroblast neural crest cell population during embryonic development of the organism.

[2] The osteoderms of modern crocodilians are heavily vascularized,[5] and can function as both armor and as heat-exchangers,[6] allowing these large reptiles to rapidly raise or lower their temperature.

Another function is to neutralize acidosis, caused by being submerged under water for longer periods of time and leading to the accumulation of carbon dioxide in the blood.

[7] The calcium and magnesium in the dermal bone will release alkaline ions into the bloodstream, acting as a buffer against acidification of the body fluids.