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ILovePuppiesLol (ilovepuppieslol):
-_-
Elsa213 (elsa213):
"Vertebrates possess two types of bone. Dermal bone consists of bony structures (plates and scales) that develop in the skin. The bony armor of the earliest jawless fish was dermal bone; so are shark scales, shoulder blades, and the roof of your skull. Dermal bone does not form from cartilage first and then calcify, but endoskeletal bone does; in fact, in cartilaginous fishes it may never form true bone. Vertebrae, ribs, appendages, and the jaw are endoskeletal bone. The vertebrate skull is actually a complex structure of both endoskeletal and dermal bone."
der :D