Size and Weight:
About Megapnosaurus (Syntarsus):
By the standards of the early Jurassic period, Megapnosaurus was huge--this early theropod (which was closely related to Coelophysis) may have weighed as much as 75 pounds, hence its unusual name, Greek for "big dead lizard." (By the way, if Megapnosaurus sounds a bit unfamiliar, that's because this dinosaur used to be known as Syntarsus--a name that turned out to have already been assigned to a genus of insect.)
As far as we know, there were two distinct species of Megapnosaurus. One lived in South Africa, and was discovered when researchers discovered a bed of 30 tangled skeletons (the pack had apparently been drowned in a flash flood). The North American variant sported small crests on its head, a hint that it was closely related to another smallish Jurassic theropod, Dilophosaurus.