Competitive swimmers know that swimming underwater causes less drag resistance than swimming at the surface. Splashing around making waves isn't the most efficient way to swim. Any energy spent ...

Riley Black’s new book, When the Earth was Green, uses the latest research to envision the ancient worlds of our favorite prehistoric animals.

This 375-million-year-old fish, the closest known relative of the ancestors of limbed animals such as humans, likely evolved the foundation for rear legs even before the move to land, researchers say.