Works on dinosaurs, focusing on problems with growth and variation, the anatomy and relationships of carnivorous dinosaurs, and the origin of birds. Has a long term goal of understanding the rich Cretaceous ecosystem of Dinosaur Park , and contemporaneous faunas and habitats of other sites in western North America. Is also interested in what can be learned about dinosaurian behaviour, including annual and intercontinental migrations.
Interested in dinosaurs since childhood, he finds that the excitement of discovery (fossils in the field, and ideas in the "lab") constantly renews his interest.
Fieldwork connected with his research has been concentrated in Alberta, British Columbia, the Arctic, Argentina and China. Work on the Centrosaurus bonebed, the origin of birds, "feathered" dinosaurs, hadrosaur nesting sites and the Canada-China Dinosaur Project have attracted the greatest international attention.