Troodon formosus was a small coelurosaurian dinosaur—a member of the same clade (evolutionary group) to which modern birds belong. Fossilized remains have been discovered of nesting parents and egg clutches. These finds shed some light on reproductive strategies that resemble those of both crocodilians and birds.
Scientists believe that Troodon produced a pair of eggs at periodic intervals and then incubated them in earth nests, sometimes sitting on them and warming them with body heat. Such behavior suggests that these dinosaurs could be an important link on the evolutionary chain, bridging the gap between their earlier relatives (crocodilians) and their later relatives (birds).
Troodon had a large brain for its relatively small size and was probably among the smartest dinosaurs. Its brain is proportionally larger than those found in living reptiles, so the animal may have been as intelligent as modern birds, which are more similar in brain size.
Troodon walked (and ran) on two long, hind legs. It probably ate small lizards, mammals, and invertebrates. The animal's rotatable forearms, which sported three-fingered hands, likely aided Troodon's hunting prowess. The dinosaur also had large, forward-facing eyes that granted it keen vision for hunting, even at night.