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DVL-0138Specimen Record
AI Reconstruction of Troodon formosus, generated in 2026

Troodon

Troodon formosus

TROH-oh-don for-MOH-sus

This brainy little predator had one of the largest brains relative to body size of any dinosaur, and was among the very first dinosaurs discovered in North America.

Did you know?

Troodon had the largest brain-to-body ratio of any known dinosaur, leading paleontologist Dale Russell to famously speculate about what it might have evolved into had dinosaurs not gone extinct

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.

First described1855
Discovered byFerdinand Vandeveer Hayden
Type specimenANSP 9259

Where fossils were found

Two Medicine Formation prehistoric landscape

Two Medicine Formation

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Modern locations

Montana, Alberta · United States, Canada

When it lived

72.266 million years ago(6.2m year span)

Where Troodon Roamed

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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.

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