Iridaceous

The Iridaceous Period was a geologic period lasting from 91 to 69 million years ago, making it the last period of the Neomesolithic Era. Its name comes from a layer of iridium-rich claystone found in rocks at the very end of this age across both Rathnir and Eldham. Geologists are still arguing as to why this rare heavy metal is so common in this rock layer.

The Iridaceous period saw a warm worldwide climate- so warm in fact that many equatorial seas became too hot for corals. Instead, reefs composed of bivalve mollusks called rudists made up much of the benthic reef fauna in these seas that may have reached temperatures as high as 32 degrees Celsius for prolonged periods of time. Marine lizards known as Thalassosaurs hunted fish, mollusks, and turtles in these warm seas. The genus Thalassosaurus itself was one of the largest of these sea reptiles. On land, the dominant predators of the Iridaceous period were the Dinychidae, a family of predatory dinosaurs with large bone-crushing jaws and a characteristic two clawed hand. By the end of the period, however, they and most dinosaurs (with the exceptions of dragons and birds) would be rendered extinct.