Sauropods were the true giants of the dinosaur family, some species attaining lengths of over 100 feet and weights of over 100 tons. Most sauropods were characterized by their extremely long necks and tails and thick, squat bodies; they were the dominant herbivores of the Jurassic period, though an armored branch (known as the titanosaurs) flourished during the Cretaceous. Among the most well-known sauropods were Brachiosaurus,Apatosaurus and Diplodocus.
Tyrannosaurs were the killing machines of the Cretaceous period: these huge, powerful carnivores were all legs, trunk and teeth, and they preyed relentlessly on smaller, herbivorous dinosaurs (not to mention other theropods). The most famous tyrannosaur was Tyrannosaurus Rex, though less well-known genera (such as Albertosaurus andDaspletosaurus) were equally deadly. Technically, tyrannosaurs were theropods, placing them in the same larger group as dino-birds and raptors.