Fig. 13.

Outgroup lizard species autopodial chondrification. Desert grassland whiptail lizard (Aspidoscelis uniparens; Teiidae) and bearded dragon (Pogona vitticeps; Agamidae) chondrification patterns show post-axial dominance in elements appearance along the metapterygial axis. A. uniparens (a, b) hands show early formation of the ulnare, distal carpals 3 and 4, metacarpals 2–5 and a diffuse staining in the area of the radiale, lateral centrale and intermedium a. This empty domain later fills with a large medial and lateral centrale b. The foot develops from less elements and completes with a fused metatarsal 5 and distal tarsal 5 and a large distal tarsal 4 c-d. A large proximal tarsal element comprising the fibulare, intermedium and tibiale + lateral centrale develops in the ankle. In P. vitticeps e-j, a very similar sequence of cartilage elements in the hand (e-g) develop relative to A. uniparens with the added intermediate stage of seeing the medial carpale segment from the proximal end of distal carpal 1 (f) while the lateral centrale shifts distally adjacent to dc2 and dc3. The tarsus is more difficult to follow due to a small sample size and diffuse staining, but the proximal tarsal element is at least formed by the tibiale, intermedium and fibulare (h-j) with centralia not distinguishable