Dinosaur Eggs

University of Bristol

Ornithopod eggs

Ornithopod eggs are best known from North America, and in particular 'Egg Mountain' in the Late Cretaceous of Montana. Examples come from the 'duck-bill' Maiasaura.

Maiasaura was a semi-quadrupedal dinosaur, probably foraging for most of its time on all fours, but maybe rearing up on its hindlimbs to escape predators. It had a solid ridge over its eyes and was 9 m in length.

The egg shell shape is not well preserved but appears overall rounded (Hirsch and Quinn,1990); 10-12 cm long and 7-9 cm wide, although slightly elongated with one end thicker than the other. The surface has ridges orientated longitudinally. This ornamentation could have strengthened the shell without unduly increasing the thickness of the shell, which would cause difficulty with respiration and hatching. The ornamentaion could have allowed the egg to buried under soil (maybe for protection or incubation). Gaps between the ridges would have allowed areas for respiration (Moratalla, 1994).

Below;Maiasauraegg-type texture (scale bar = 10 mm)

The crystals are dinosauroid; spherulitic with crystals growing in a spherical fashion. Other ornithipod eggs were thought to come also from this locality. Eggs thought to belong to Orodromeus, are now thought to belong to a different dinosaur, the theropod Troodon.

Back to Dinosaur egg types