Fig. 16

Chamaeleo calyptratus atuopodial skeletogenic condensations. Despite a very specialized and element reduced adult chameleon autopodial skeleton, most ancestral skeletal elements remained present through ontogeny with the exception of the centralia. Between the manus and pes, the preaxial elements were always significantly delayed (ra, ti) in appearance. The intermedium appeared to have a ‘dual’ origin, with its condensation occurring closer to the radius in the forelimb and the fibulare in the hindlimb. We found that elements condensed and completed skeletogenesis (metacarpals, at least half of the distal carpals/tarsals, pisiform). There was a high tendency for fusion amongst proximal elements of the foot in C. calyptratus despite delayed appearance of the tibiale. Distal carpal 1 and distal tarsal 2 were seen to condense as mesenchyme but later fuse to adjacent elements while we were unable to find any condensation for distal tarsal 1. Distal carpal 3 remains cartilaginous. The pisiform was found to be derived through segmentation of the ulnare and the fibularis brevis tendon to enclose a sesamoid