The Snow Skink is the first reptile to determine sex of the offspring in two locations with completely different methods. We as humans know there are a variety of way to determine sex of an incubating clutch, but with these guys, they do it on their own.

From ABC Science:

At low altitudes, the lizard's gender is determined by temperature, while at high altitudes where the climate is more extreme, it's all down to their genes, according to a study in Nature.
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The snow skink is a small six centimetre long lizard which lives in coastal and sub-alpine areas beneath rock slabs, eating insects and wild berries. It gives birth to live young rather than laying eggs, producing between one and six babies.
Previous research shows that the sex of baby skinks is determined during the first half of the pregnancy, depending on how long the mother remains in warm sunshine. Warm temperatures generally produce females, while cooler temperatures produce males.
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The researchers found that lowland mothers had very different ratios of boys to girls, depending on how much sunshine they had. By contrast, the highland mothers showed no difference in sex ratio of offspring, regardless of how long they spent in the Sun

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