The Maiasaur nest consisted of a hollowed-out bowl about two meters across and one meter deep at the centre and appeared to have been built up from the ground with a rim about 75 centimeters high. They have been fittingly described as miniature volcanoes.

The nests were primarily made of the mudstone typical of the Two Medicine Formation and lined with ample vegetation for incubation. As the decaying plant material fermented, it would generate the heat necessary for incubation. The heat could be regulated by the addition or removal of the plant material.