Bony structure derived from intramembranous ossification
Adermal bone orinvesting bone ormembrane bone is a bony structure derived fromintramembranous ossification forming components of thevertebrateskeleton, including much of theskull,jaws,gill covers, shoulder girdle,fin rays (lepidotrichia), and the shells ofturtles andarmadillos. In contrast toendochondral bone, dermal bone does not form from cartilage that then calcifies, and it is often ornamented.[1] Dermal bone is formed within thedermis and grows by accretion only – the outer portion of the bone is deposited byosteoblasts.
The function of some dermal bone is conserved throughout vertebrates, although there is variation in shape and in the number of bones in theskull roof and postcranial structures. Inbony fish, dermal bone is found in the finrays and scales. A special example of dermal bone is theclavicle. 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]
^Clarac, F.; Goussard, F.; de Buffrénil, V.; Sansalone, V. (2019). "The function(s) of bone ornamentation in the crocodylomorph osteoderms: a biomechanical model based on a finite element analysis".Paleobiology.45 (1):182–200.doi:10.1017/pab.2018.48.S2CID92499041.
^Jackson, D.C.; Goldberger, Z.; Visuri, J.; Armstrong, R.N. (1999). "Ionic exchanges of turtle shell in vitro and their relevance to shell function in the anoxic turtle".Journal of Experimental Biology.202 (5):503–520.doi:10.1242/jeb.202.5.513.PMID9929454.
