Figure 6

Paralyzed embryos fail to develop an opposable hallux:
(a) Paralyzed chicken embryos at HH40 showing the maintenance of the medial orientation of the hallux; (b) Paralyzed chicken embryos exhibit the hallux articulated to the ventral Mt2 but not opposable; (c) Mt1 of paralyzed chicken embryos are straight, as opposed to control embryos; (d) Mt1 of paralyzed embryos at HH38 immunostained for COLIX resembles the non-twisted Mt1 of early tetanuran dinosaurs, as Allosaurus. (See SI, Movie 2).