part of part of connective tissue skeletal tissue A specialized form of connective tissue in which the extracellular matrix is firm, providing the tissue with resilience, and/or mineralized and that functions in mechanical and structural support.[VSAO] A specialized form of connective tissue in which the extracellular matrix is firm, providing the tissue with resilience, and/or mineralized and that functions in mechanical and structural support.[VSAO] Four classes of mineralized tissues are found in vertebrates: bone, cartilage, dentine, and enamel. We think of cartilage and bone as skeletal tissues and of enamel and dentine as dental tissues, but enamel and dentine arose evolutionarily together with bone as skeletal tissues in the dermal skeleton (exoskeleton) of early vertebrates. Scales and teeth of sharks are examples of dermal skeletal elements that are still composed of the three ancient components-enamel, dentine, and bone. Cartilage, on the other hand, provided the basis for the second vertebrate skeletal system, the endoskeleton (Smith and Hall, 1990; Hall, 1998a,b). some invertebrate skeletal tissues have surprisingly bone-like features. Examples include chondrocytes interconnected by cell processes in cephalopod cartilages (Cole and Hall, 2004a,b), and the calcium phosphate layer in the shells of brachiopods (Rodland et al., 2003). However, neither bone nor mineralized cartilage have been found in invertebrates. Editors notes: TODO - develops_from MA:0003047 UBERON:0004755 VSAO:0000015 XAO:0004038 ZFA:0005619 uberon skeletal element