Viviparity: Reptiles
Viviparity only evolved in squamates, but independently numerous times (>100X).
- Entirely viviparous: Xenosauridae, Xantusiidae, Aniliidae, Uropeltidae, Acrochordidae, Tropidophiidae
- At least 34 derivations in Scincidae; at least 14 derivations in Colubridae
- Rare in many other ‘families’
Evolution of viviparity thought to be associated with cool environments.
- More rapid development _ thermoregulating female