Dinosaur Intelligence: Brains and Behavior

Were dinosaurs intelligent? The answer depends on what we mean by intelligence and which dinosaurs we are discussing. The range of cognitive abilities across dinosaurs was enormous.

Brain size is estimated from endocasts — natural or artificial casts of the braincase interior. The encephalization quotient (EQ) compares brain size to expected brain size for an animal of that body mass. Most dinosaurs had EQs similar to modern reptiles, but some were remarkable exceptions.

Troodontids had the largest brains relative to body size of any non-avian dinosaur, with EQs comparable to modern birds. Their large eyes and binocular vision suggest sophisticated visual processing. Dromaeosaurids (raptors) also had relatively large brains.

Sauropods, despite their enormous bodies, had tiny brains. Stegosaurus had a brain about the size of a walnut. The myth of a second brain in its hip (actually an enlargement of the spinal cord) has been thoroughly debunked.

Behavioral evidence comes from trace fossils and exceptional preservation. Trackways show herd behavior in sauropods and coordinated movement in theropods. Nesting sites demonstrate parental care in hadrosaurs and oviraptorosaurs. The Fighting Dinosaurs fossil from Mongolia preserves a Velociraptor and Protoceratops locked in combat.

Modern birds provide our best model for understanding advanced dinosaur cognition. Crows, parrots, and other corvids demonstrate problem-solving, tool use, and complex social behaviors. These cognitive abilities evolved within the dinosaur lineage, and the neural foundations were likely present in their non-avian relatives.