Were the first amniotes semi-aquatic?
Previously, I explored the possibility of early amniotes being semi-aquatic in my article about early aquatic mammals, and it seems this might be true after all:
Canoville, A. and M. Laurin. 2010. Evolution of humeral microanatomy and lifestyle in amniotes, and some comments on paleobiological inferences. Biological Journal of the Linnean Society 100:384–406.