part of develops from start stage end stage olfactory region kinethmoid cartilage dermatocranium kinethmoid bone Small median unpaired dermal sesamoid bone in the premaxillary-ethmoid ligament between the mesethmoid and the premaxilla that enhances the protractability of the upper jaw. It forms in the premaxillary-ethmoid ligament. The kinethmoid arose de novo in the ancestor of Cypriniformes, the only group within Ostariophysi, in which it is found (Fink and Fink, 1981). TAO:0001406 zebrafish_anatomy ZFA:0001406 chondrocranium dermal bone larval:days 21-29 adult