The third period of the Mesozoic Era, from 145 to 65 million years ago; a continuation of the Jurassic heyday of the dinosaurs. It ended in a major extinction event that was also the close of the Mesozoic and the beginning of the Cenozoic.
The Cretaceous was a period of high tectonic and volcanic activity. The overall climate was mild, and the atmosphere was rich in both oxygen and carbon dioxide relative to the modern periods. Continents began to have a modern-day look, with the break-up of Gondwanaland, though to a casual eye the extensive epicontental seas would have concealed this.
Amongst the vertebrates, primitive mammals including early marsupials and placentals developed, and the first modern crocodilians appeared. The earliest-known butterflies appear (about 130 million years ago) as well as the earliest-known ants and bees. In the plant world, this period saw the first major radiation of flowering plants. Minor extinctions occurred at 120 and 82 million years ago. The Cretaceous ended with a class 4 mass extinction (the K-T extinction) of dinosaurs, pterosaurs, ammonites, and about 50 percent of marine invertebrate species, probably caused by asteroid impact in conjunction with extended volcanism.
During the long period of dinosaurian Cretaceous dominance on Earth, many alien empires arose and disappeared elsewhere in the galaxy, including Planetary Civilization HIE565MZE and the most recent appearance of the Jacks, while the ancient Muuh first evolved into sophont beings.
Cretaceous reconstructions and lazurogenized biospheres are quite popular with some Terragen clades, and there are a number of good and authentic ecosystems, although as is often the case there is generally some fudging with many species, especially invertebrates, and the usual cross-mixing with non-Cretacean species is also common.
K-T Extinction - Text by M. Alan Kazlev Terragen mass extinction that occurred 65 million years ago, at the boundary of the Cretaceous and Tertiary periods. Caused by an asteroid or comet impact on the Yucatan Peninsula, resulting in prolonged darkness and rapid global temperature change. It resulted in the extinction of a number of important groups of animal life, including dinosaurs, plesiosaurs, mosasaurs, pterosaurs, ammonites, and several groups of plankton. Plants, small invertebrates, small reptiles and amphibians, small birds, and nocturnal mammals were not unduly affected, and large scavenging reptiles (crocodiles) also were able to survive. The K-T extinction event was a Level IV Mass Extinction.