Today, after adding Rana to the matrix of the large reptile tree (still not updated), I think it’s time we looked at the antorbital fenestra of Rana, and the lateral temporal fenestra as well (Fig. 1).
One usually thinks of additional skull fenestrae in the province of reptiles. As we saw earlier, the antorbital fenestra comes and goes in several reptiles. So does the lateral temporal fenestra. Amphibians (non-amniote tetrapods) typically do not have skull fenestrae. Neither to most basal reptiles.
Relative to the body, the skull of Rana is enormous. So are the hind limbs. Frogs leap, as everyone knows, and if the skull is going to be large it also has to be lightweight to enable longer leaps. So the skull bones are reduced to their bare minimum creating fenestrae.
Proximal outgroup taxa, including long-legged Triadobatrachus, likewise have reduced skull bones.