Which dinosaur had a long hollow crest on its head?

The dinosaur with a long hollow crest on its head was Parasaurolophus. Its remarkable crest projected backward from the skull and was built from extensions of the premaxilla and nasal bones.

The crest was not a solid horn. It contained elaborate air passages that ran from the nostrils to the end of the crest and back toward the skull. Scientists think these tubes may have helped produce resonant calls, allowing Parasaurolophus to communicate across its Late Cretaceous environment. The crest may also have served as a visual signal for recognizing members of the same species or displaying maturity.

Parasaurolophus was a hadrosaurid, or duck-billed dinosaur, and lived roughly 76–73 million years ago. Its fossils are known mainly from western North America. The name means “near crested lizard.”

A common mix-up is with Corythosaurus and Lambeosaurus, which also had hollow head crests. Their crests were shaped differently, while Parasaurolophus is especially recognizable for its long, backward-curving tubular crest.