English: Reconstruction of troodontid dinosaur. Orignally intended to represent 'Troodon, it might rather resemble Stenonychosaurus. This is an updated version of a drawing i uploaded in December of 2009.

Troodon formosus ( "Wounding tooth") was named in 1858 on the basis of a single tooth, and was one of the first dinosaurs ever described in North America. Over the years that followed, more complete skeletons of birdlike dinosaurs with teeth resembling the Troodon holotype were found, One of these were Stenonychosaurus (named by Sternberg in 1932). In the 1980s, Currie suggested that Stenonychosaurus' were synonomous with Troodon.

In 2017, other scientists suggested that Troodon is a nomen dubium and that Stenonychosaurus is a separate taxon.