Ornithischia
Available for editorial, museum & print licensing — inquiries & rates →
A saurolophine hadrosaurid (duck-billed dinosaur) from the Late Cretaceous of Montana. Maiasaura is famous from vast bonebeds and nesting colonies that provided the first strong evidence of parental care in dinosaurs, inspiring its name, “good mother lizard.”
The evidence
Maiasaura from hatchling to adult. Maiasaura is mostly known from bonebeds, so outside of the adult, the growth stages are composed of composite skeletals, rather than skeletals based on individual specimens.
Quite a lot happens as a young Maiasaura grows up. As a hatchling, the head and femur (upper leg bone) are about the same length. By the yearling stage the femur has pulled ahead, and the ratio changes comparatively little after that — most of the shift in head proportion happens in the first year of life.
| Stage | Length m | Skull m | Femur m | Humerus m | Skull ÷ femur | Humerus ÷ femur |
|---|---|---|---|---|---|---|
| Adult | 7.5m | 0.75m | 0.97m | 0.51m | 0.77 | 0.53 |
| Subadult2 yr | 5m | 0.54m | 0.72m | 0.39m | 0.75 | 0.54 |
| Yearling | 2.75m | 0.28m | 0.41m | 0.20m | 0.68 | 0.49 |
| Hatchling | 0.5m | 0.07m | 0.07m | 0.04m | 1.00 | 0.57 |
Hatchling
Yearling
Subadult (two years)
