The classification of Troodon as a pachycephalosaur was followed for many years, during which the family Pachycephalosauridae was known as Troodontidae.
In 1924, Gilmore suggested that the tooth belonged to the herbivorous pachycephalosaur Stegoceras, and that Stegoceras was in fact a junior synonym of Troodon (the similarity of troodontid teeth to those of herbivorous dinosaurs continues to lead many paleontologists to believe that these animals were omnivores). The Troodon tooth was originally classified as a "lacertilian" (lizard) by Leidy, but reassigned as a megalosaurid dinosaur by Nopcsa in 1901 (Megalosauridae having historically been a wastebin taxon for most carnivorous dinosaurs). But they have bigger bumps running down on it. They have serrates like normal carnosaurs. Troodon is also known for its special teeth. Even a fully grown 12 metre long Edmontosaurus can be taken down by this clever dinosaur. It also specializes in pack hunting to hunt bigger prey. Troodon ate mammals, small dinosaurs, eggs and junvenille Hadrosaurs.
This slender little dinosaur might be the most intelligent dinosaur ever to exist. It lived in what is now North America during the late Cretaceous Period (100-65 mya) and grew to be about 8 feet (2.4 meters) to 10 feet (3.2 meters) long and about 110 lbs. Troodon, however, is generally accepted as having been endothermic, otherwise known as warm - blooded outside the scientific community, although disputes still occur. Troodon had abnormally large eyes, and these helped Troodon to see after the setting of the sun, territory which was traditionally undisturbed by those of the great order Reptilia, due to the restrictions of being ectothermic (unable to maintain a constant internal temperature).
Recent studies also seem to suggest that it was also feathered. It had the typical lightweight theropod build, and may have had camouflage markings on its hide, to help it catch the nocturnal mammals which formed a small part of its diet. Troodon (wounding-tooth) (also known as Troödon, sometimes Stenonychosaurus or Polyodontosaurus) is a large-brained nocturnal Troodontid theropod, which lived in the latter part of the Cretaceous period.