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28 Nov 2018
It seems unlikely that an ovoviparous ancestor of mammals longago could have had a viviparous offspring in a sharp one-generationdividing line, but what would be the gradual steps between eggbirth and live birth? Are there any examples of answers to thefirst question today? It seems that marsupials are a differentthing altogether, not something in between egg laying and livebirth (no modern mammal's ancestors aren't believed to havemarsupial-style birth in their evolutionary history, right?)?
It seems unlikely that an ovoviparous ancestor of mammals longago could have had a viviparous offspring in a sharp one-generationdividing line, but what would be the gradual steps between eggbirth and live birth? Are there any examples of answers to thefirst question today? It seems that marsupials are a differentthing altogether, not something in between egg laying and livebirth (no modern mammal's ancestors aren't believed to havemarsupial-style birth in their evolutionary history, right?)?
Patrina SchowalterLv2
29 Nov 2018
