Troodon formosus

Troodon Temporal range: Late Cretaceous, 77.5–74.5 Ma PreЄ Є O S D C P T J K Pg N ↓
Restored skeleton of an unnamed Alaskan species, Perot Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	†Troodontidae
Subfamily:	†Troodontinae Gilmore, 1924
Genus:	†Troodon Leidy, 1856
Type species
†Troodon formosus Leidy, 1856
Other species
†T. inequalis (Sternberg, 1932) And see text.
Synonyms
Polyodontosaurus Gilmore, 1932 Stenonychosaurus Sternberg, 1932

†T. inequalis (Sternberg, 1932)
And see text.

Polyodontosaurus Gilmore, 1932
Stenonychosaurus Sternberg, 1932

Troodon (/ˈtroʊ.ədɒn/ TROH-ə-don; Troödon in older sources) is a genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Cretaceous period (about 77 mya), though possible additional species are known from later in the Campanian and also from the early (and probably late) Maastrichtian age. It includes at least one species, Troodon formosus, though many fossils, possibly representing several species have been classified in this genus. These species ranged widely, with fossil remains recovered from as far north as Alaska and as far south as Wyoming and even possibly Texas and New Mexico. Discovered in 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877.