The expression of these genes thus seems shifted relative to each other, possibly in relation to the deregionalization of the snake body plan.
However, due to lack of Hox expression data from non-snake squamates these differences in expression could also represent a synapomorphic squamate character.
Therefore, we investigated the expression boundaries of HoxC5, HoxC6, HoxB6 and HoxB8 in the bearded dragon lizard (Pogona vitticeps) and of HoxA6 in the green anole lizard (Anolis carolinensis).
These species have 4 ribless neck vertebrae and the forelimbs are positioned between vertebra 6 and 7 (data not shown).