Temporal range: Late Cretaceous
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An artist's interpretation of Troodon formosus
The Childrens Museum of Indianapolis - Troodon teeth.jpg
Teeth from South Dakota assigned to T. formosus, with a US dime coin for scale, Children's Museum of Indianapolis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Suborder: Theropoda
Family: Troodontidae
Subfamily: Troodontinae
Genus: Troodon
Leidy, 1856
Species: T. formosus
Binomial name
Troodon formosus
Leidy, 1856

Troodon (Troödon in older sources) is a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Cretaceous period (about 77 mya). It includes at least one species, Troodon formosus, is known from Alberta and Montana. Discovered in 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877.

The genus name is Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The teeth bear prominent, apically oriented serrations. These "wounding" serrations, however, are morphometrically more similar to those of herbivorous reptiles, and suggest a possibly omnivorous diet.[1]

For a long time, Stenonychosaurus inequalis was thought to be a synonym of Troodon formosus or a separate species, T. inequalis, but a 2017 study by Aaron J. van der Reest and Phillip Currie revived the genus.[2]. The same paper noted that Troodon lacked any features separating it from most troodontids and suggested that Troodon formosus should be a nomen dubium.


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). 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 classification of Troodon as a pachycephalosaur was followed for many years, during which the family Pachycephalosauridae was known as Troodontidae. In 1945, Charles Mortram Sternberg rejected the possibility that Troodon was a pachycephalosaur due to its stronger similarity to the teeth of other carnivorous dinosaurs. With Troodon now classified as a theropod, the family Troodontidae could no longer be used for the dome-headed dinosaurs, so Sternberg named a new family for them, Pachycephalosauridae.
The dinosaur book - the ruling reptiles and their relatives (1945) (20956782365)

Troodon as a pachycephalosaur Like the film Fantasia.

Scientists at a British university later conducted a thought experiment related to the evolution of Troodon, had it not been so brutally wiped out by the cataclysmic meteorite impact of 65 million years ago. The scientists 

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Patch, the Troodon, from March of the Dinosaurs

discovered that, as Troodon's eyes grew, his head would have to frequently bend upwards to gain a better view. The only way to solve that problem was to change the angle at which the spine was to the ground, in other words, to become erect. With Troodon standing upright, there would be no need for a tail to act as a counterbalance, henceforth reducing the requirement for a tail. Troodon had become humanoid. Although this is just a thought experiment, it really does give a fascinating glimpse of what evolutionary paths certain lineages of dinosaur may have taken to, had they not been eradicated. This little carnivore was a relative of Saurornithoides, another type of Troodontid.

Troodon Size Comparison

In 2017, Aaron J. van der Reest and Currie resurrected Stenonychosaurus as a valid genus.[2]

In the Media

  • The video game Prehistoric Kingdom will have the main species of Troodon and the larger polar species of Troodon.
  • Troodon is mentioned in The Lost World novel. John Roxton discovered what he believed to be a Velociraptor skeleton in Mongolia. However, it was actually a Troodon skeleton (even though the Troodon genus is only found in North America, although there are troodonids in Asia). The fossil discovered had impressions of its skin.
  • Troodon is one of the available dinosaurs on the IOS application, Jurassic Park: Builder. The Troodon uses the same animations of Compsognathus and Velociraptor.
  • Troodon was added to Jurassic World: The Game on January 4, 2016, but is a limited tournament dinosaur. It is a legendary carnivore. While it is accurately portrayed with a coat of feathers, it is shown inaccurately to be able to pronate it's hands.
  • A pack of Troodons can be seen in Jurassic Park The Game at the beginning and in other parts of the game. They are said to be venomous in the game, which is very unlikely. It is important to note that the species of Troodon in the game is the fictional species "Troodon pectinodon" (the name is combined with the genus Pectinodon for the species name) and not an existing species. The Troodons in the game, even though claimed to be created only using Troodon DNA, but still have pronated wrists and minimal quill-like feathers.
  • Troodon will be added to Jurassic World: Evolution on November 20 2018. It will have a poisonous bite, much like Jurassic Park: The Game.
  • It will appear in ARK: Survival Evolved. It seemed to be very similar to the Jurassic Park: The Game, so any inaccuracies with the JP Troodon is the same as the ARK version.
  • Troodon also appeared in Fantasia attacking an Archaeopteryx. While many viewers assume it was an Ornitholestes, the scripts confirm it's a Troodon. In the film, Troodon is depicted as having a domed head and horns, since at that time it was assumed to be a pachycephalosaur.
  • Troodon have appeared on an animated PBS Jim Henson show Dinosaur Train. The supported known Troodon of the series is Mr. Conductor. Sometimes called Mr. The Conductor by Don Pteranodon.
  • Kate Elliot's Spiritwalker book trilogy features 'trolls' that she acknowledges being descended from Troodon.



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