About
Troodon was a small, lightly built dinosaur that prowled the forests and floodplains of Late Cretaceous North America. Standing roughly waist-high to a human, this agile predator possessed unusually large eyes that faced partially forward, granting it well-suited for hunting in low-light conditions. Its slender build, long legs, and grasping hands made it an efficient pursuit predator, likely feeding on small mammals, lizards, and perhaps eggs.
What truly sets Troodon apart is its remarkably large brain relative to its body size—among the highest ratios of any known dinosaur. While we cannot directly measure intelligence in extinct animals, this brain-to-body ratio has led to considerable speculation about Troodon's cognitive abilities. Its large, forward-facing eyes and specialized inner ear structure suggest sophisticated sensory processing that would have made it a formidable hunter, particularly at dawn and dusk.
Troodon holds a special place in paleontological history. Discovered in October 1855 by Ferdinand Hayden in Montana, it was among the first dinosaurs found in North America. However, the specimen—a single tooth—was initially misidentified as belonging to a lizard. It wasn't until 1877 that Joseph Leidy recognized its dinosaurian nature, though the has made Troodon's taxonomy controversial ever since.
The genus has become something of a "," with many specimens from across North America historically assigned to Troodon based on limited material. Recent studies have questioned whether these specimens truly represent a single genus, and some paleontologists now consider Troodon formosus a dubious name that should be restricted only to the original tooth specimen, with other material reassigned to different genera like Stenonychosaurus or Latenivenatrix.
Explore the anatomy
5 featuresThose massive eye sockets faced forward like an owl's, giving Troodon overlapping vision from both eyes—perfect for judging distances in dim light. Preserved eye bones suggest its eyes were as large as a modern owl's compared to its skull size, making it a twilight hunter built to spot prey when other dinosaurs were calling it a night.
That wicked curved claw on the second toe stayed lifted off the ground while walking, keeping it razor-sharp like a pocket knife held ready. Scientists think it wasn't for slashing—instead, Troodon probably used it like a thumbtack to pin down small, squirming prey.
Brain casts show Troodon had one of the largest brains compared to body size of any non-bird dinosaur, with extra space dedicated to vision, smell, and balance. This wasn't necessarily "genius-level" smarts—more like a supercomputer for processing what its sharp senses were picking up.
Here's a wild fact: the entire species was named from a single tooth found in 1855, and that tooth is still the only specimen scientists can definitely assign to Troodon—making it both famous and scientifically frustrating. Those teeth have saw-like edges on both sides and look oddly similar to plant-eater teeth, hinting this dinosaur might have eaten more than just meat.
The lower leg bone was longer than the thigh bone—a body plan that screams "built for speed" in both dinosaurs and modern birds. Combined with a stiff tail for balance, these legs powered a swift hunter that could sprint across ancient floodplains and forest edges chasing down prey.
Where fossils were found
Two Medicine Formation
+3 more formations
Montana, Alberta · United States, Canada
72.2–66 million years ago(6.2m year span)
Where Troodon Roamed
During the late Cretaceous period, Troodon formosus inhabited the coastal plains and river deltas of western Laramidia, a landmass separated from eastern North America by the vast Western Interior Seaway that stretched from the Gulf of Mexico to the Arctic Ocean. This warm, humid environment supported lush subtropical forests and diverse ecosystems where this sharp-eyed predator hunted small prey beneath towering conifers and flowering plants.
Keep exploring the vault
Maiasaura
Maiasaura peeblesorum
Troodon eggs and nests have been found in close association with Maiasaura nesting grounds in the Two Medicine Formation.
Edmontosaurus
Edmontosaurus regalis
Troodon co-occurs with Edmontosaurus in the Horseshoe Canyon Formation.
Oviraptor
Oviraptor philoceratops
Both Troodon and oviraptorosaurs were small, intelligent theropods known to inhabit nesting grounds and consume eggs.
Microraptor
Microraptor gui
Both are small, feathered maniraptorans representing the evolutionary experimentation with intelligence, agility, and possibly nocturnal/crepuscular activity.
Anchiornis
Same family: Troodontidae
Corythosaurus
Corythosaurus casuarius
Both occur in the Dinosaur Park and Two Medicine Formations.