Saurolophus have a long cranial crest with internal chambers that were responsible for respiratory functions or heat regulation.
The most distinctive feature of Saurolophus is its cranial crest, which is present in young individuals, but is smaller. It is long and spike-like and projects upward and backward at about a 45 angle, starting from over the eyes. This crest is often described as solid, but appears to be solid only at the point, with internal chambers that may have had a respiratory and/or heat-regulation function. Maryanska and Osmolska, noting the hollow base, suggested that the crest increased the surface area of the respiratory cavity, and helped in thermoregulation. 
