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. 　　译文(2): 随着恐龙成长为白垩纪中的庞然大物，它们进化出了许多非同寻常但显然毫无用处的特征，包括尖刺、帆角、羽冠和霸王龙的小“手臂”。该节目回顾了这些不寻常的特征，并讨论了它们为什么存在的理论。