As dinosaurs grew into the behemoths of the Cretaceous period they evolved many extraordinary but apparently useless features including spikes, sails horns, crests and the tiny "arms" of tyrannosaurs. The program reviews these unusual features and discusses theories of why they exist.

Starring:

Jack Horner, Paul Sereno, Gregory Erickson, Lawrence Witmer, Robert Bakker, Kristi Curry Rogers, Mark Norell, Phil Manning, Roger Tilling

Genre:

Documentary