Lizards reproduce in an amazing variety of ways. Some lay eggs (oviparity) and some bear live young (viviparity). Most species rely mostly on egg yolk for nutrition during embryonic development; a few have next to no yolk and rely completely on a placental connection to the mother. Some lizard placentas even compare with the complexity of mammalian placentas. Some species can vary the timing of birth. There are a rare few species that even have variety in their reproductive mode.

National Geographic recently reported on one of these rare few species that have differing reproductive modes between populations—one of only three in the world—the yellow-bellied three-toed skink Saiphos equalis.

S. equalis is a small skink located mainly from the mountains to the coastline of New South Wales, Australia….

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