Lateral views of the heads of five species of lizard. Diurnal lizards exhibit ocular elongation and retraction, while the nocturnal lizards do not.
This eye elongation/retraction during embryonic development is typical of diurnal lizards exhibiting #foveae — specialized pits in the retina that aid in high-acuity vision and light filtering. Here are some comparisons with three diurnal lizards on the top & two nocturnal lizards on the bottom. 5/x
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