Image: Male and female Parasaurolophus skulls
Skulls of a possible male (above) and female (below) Parasaurolophus (hadrosaur).
- © Australian Museum
It is often suggested that the crests of hadrosaurs like Parasaurolophus show consistent size differences and that those with more prominent crests could be males. The fact that physical differences between sexes occur with many living animals suggests that this may be a possibility. Unfortunately, the fossil evidence is difficult to interpret.