Parasaurolophus

Chapter • Meet the dinosaur

Overview

Parasaurolophus walkeri was a large duck-billed dinosaur roughly 9–10 metres long and weighing an estimated 2–2.7 tonnes. Its defining feature is the long, backward-sweeping tubular crest, close to a metre long in the type specimen. The crest was hollow: paired nasal passages ran from the nostrils up through the tube, looped back, and returned to the throat. The body was deep-chested and heavily muscled, with a laterally flattened tail held horizontally as a counterbalance, robust hind limbs and slimmer forelimbs ending in hoof-like fingers. Skin impressions preserved alongside the holotype show small, irregular tubercles — Parasaurolophus was scaly, not feathered. The animal was facultatively bipedal. It most likely grazed and browsed on all fours, rising onto its hind legs to run or to reach higher vegetation, with top speeds estimated at around 25–35 km/h. Acoustic modelling of the crest's airways, including work carried out at Sandia National Laboratories in the 1990s, suggests the animal could generate deep, low-frequency resonant calls, rather like a living brass instrument. Such sounds would have carried far across open floodplains and fit well with a herd-living herbivore that needed to keep contact with its group and warn of predators such as Gorgosaurus. Crest shape changed with age and varied between individuals, so it almost certainly served as a visual signal too. Parasaurolophus fed on plants from ground level up to about four metres: conifers, ferns, seed ferns and the flowering plants that were spreading through Late Cretaceous landscapes. The toothless front of the broad beak cropped vegetation, while hundreds of tightly packed teeth in the cheek region formed dental batteries. As the jaws closed, the upper tooth rows swung slightly outward — a motion called pleurokinesis — grinding tough plant matter to pulp in a chewing system every bit as capable as that of modern grazing mammals. The holotype, ROM 768, was excavated in 1920 along the Red Deer River in Alberta, Canada, by Levi Sternberg for the Royal Ontario Museum, and described in 1922 by William Parks. The species name honours Sir Byron Edmund Walker, chairman of the museum's board. The specimen lacks most of the lower legs and the end of the tail but preserves the skull, crest and skin impressions. The genus name means roughly "near Saurolophus", referring to a superficially similar crested hadrosaur. Two further species, P. tubicen and P. cyrtocristatus, were later named from New Mexico and Utah in the United States.

Chapter • Where it lived

Habitat

Parasaurolophus walkeri lived about 76.5–74.5 million years ago during the Campanian stage of the Late Cretaceous. Its fossils come from the Dinosaur Park Formation of southern Alberta, Canada, especially along the Red Deer River in what is now Dinosaur Provincial Park. The setting was a humid, subtropical coastal plain on the western shore of the shallow Western Interior Seaway, crossed by meandering rivers and dotted with lagoons, swamps and forests of conifers, ferns and early flowering plants. Parasaurolophus shared this landscape with other hadrosaurs, horned dinosaurs such as Centrosaurus and Chasmosaurus, armoured dinosaurs and tyrannosaurs like Gorgosaurus.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy