They named the movie after the park because it is the same with the book. The book, Jurassic Park by Michael Crichton, also has the park named after the name of the book. So most likely Crichton...
It refers to the Jurassic period. The time in which the dinosaurs lived is called the "Mesozoic Era." The Mesozoic Era is comprised of three main periods, or ages: the Triassic period (approximately...