The mother creates the eggshell just before she lays and it would appear in this case that something upset the process. The shells are uneven, suffocating the embryos under too many layers of calcium in some places. Acid rain dissolves away nutrients in the environment which are needed to help the Tyrannosaurus create eggshell inside her body. The long mournful mating call of the female Tyrannosaurus echoes through the forest. Without eggs or young to care for, females quickly become fertile again but finding a mate can take some time.
Males are solitary and rarer than the females.
Battle for supremacy A herd of Torosaurus appear on the coastal plains. They have magnificent crests. Two metre long frills set over a three-horned face. Although this huge decoration can protect the animal, it is primarily intended to impress mates and intimidate rivals. There are no permanent hierarchies within the herd.