Many animals in the ancient world were huge. In the Paleozoic Era, cockroaches were as big as house cats! Is it possible that environmental conditions or Cope's Rule had a hand in creating behemoths?

Originally released by Smithsonian Media, 2014. Streaming video file encoded with permission for digital streaming by Infobase on March 10, 2015.

Why Were Prehistoric Animals So Big?: Ask Smithsonian (1:00); .