A dermal bone or investing bone or membrane bone is a bony structure derived from intramembranous ossification forming components of the vertebrate skeleton, including much of the skull, jaws, gill covers, shoulder girdle, fin rays (lepidotrichia), and the shells of turtles and armadillos.
In bony fish, dermal bone is found in the fin rays and scales.
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.