Dermal bone

lepidotrichia), and the shells of turtles and armadillos. In contrast to endochondral bone, dermal bone does not form from cartilage that then calcifies, and it is often ornamented.^[1] Dermal bone is formed within the dermis and grows by accretion only – the outer portion of the bone is deposited by osteoblasts

rays and scales. A special example of dermal bone is the clavicle. Some of the dermal bone functions regard biomechanical aspects such as protection against predators.^[2][3][4] The dermal bones are also argued to be involved in ecophysiological implications such as the heat transfers between the body and the surrounding environment when basking (seen in crocodilians) ^[5] as well as in bone respiratory acidosis buffering during prolonged apnea (seen in both crocodilians and turtles).^[6][7] These ecophysiological functions rely on the set-up of a blood vessel network within and straight above the dermal bones. ^[8]