Maiasaura
Reborn as a Maiasaura, you would start life in a crowded nesting colony in Montana – one of the first places where scientists found evidence that dinosaur parents looked after their babies.
The colony at Egg Mountain
In 1978 Jack Horner and Bob Makela were shown a few small dinosaur bones from a rock shop in Montana. That led them to a site in the Two Medicine Formation, about 76 million years old, where they found nests, eggs, embryos and juveniles of a new hadrosaur. In 1979 they named it Maiasaura peeblesorum – “good mother lizard”, deliberately using the feminine form.
The nests were bowl-shaped mounds about 2 metres across, spaced roughly an adult’s body length apart – a colony, like those of modern seabirds. The area became known as Egg Mountain. In 1985 Maiasaura bones flew into orbit aboard the Spacelab 2 mission – often described as the first dinosaur in space – and the same year it became the state fossil of Montana.
Childhood in the nest
The hatchlings in the nests were already larger than when they emerged from the egg and had worn teeth, while their leg joints seemed not fully developed. Horner argued they stayed in the nest for some time and were brought food by adults. That interpretation is still widely cited, though some researchers think hatchlings may have been more mobile than first thought.
Growing up fast, dying young
A 2015 study of the growth rings in more than 50 Maiasaura shinbones built one of the best life tables for any dinosaur. It showed that youngsters grew quickly, reaching adult size of about 7–9 metres in roughly eight years, and that death rates were very high in the first year – around 90% of hatchlings may not have survived it. Those who made it through faced another dangerous phase around maturity.
Large bonebeds suggest Maiasaura lived in big herds, perhaps thousands strong, which may also have made them easy targets for predators and catastrophic events.
