Sinosauropteryx
"Sinosauropteryx" was a small bipedal theropod, noted for its short arms, large first finger (thumbs), and long tail. The taxon includes some of the smallest known adult non-avian theropod specimens, with the holotype specimen measuring only in length, including the tail. However, this individual was relatively young. The longest known specimen reaches up to in length, with an estimated weight of .
Dinosaur size
"Tyrannosaurus" was for many decades the largest theropod and best-known to the general public. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including "Spinosaurus", "Carcharodontosaurus", and "Giganotosaurus". These large theropod dinosaurs rivaled or even exceeded "Tyrannosaurus" in size, though more recent studies show some indication that "Tyrannosaurus", although shorter, was the heavier predator. There is still no clear explanation for exactly why these animals grew so much larger than the land predators that came before and after them.