Cretaceous Period

The Cretaceous Period is the period of time from about 140 million to 65 million years ago (ages vary). Associated with it are warmer global temperatures and no major glaciers, which enabled the survival of large reptile dinosaurs, such as the Tyrannosaurus rex and the Triceratops. It is also the time of the appearance of modern insects, flowering plants, and new mammal species.
 PeriodMillions of Years AgoLife Forms
CeneozoicQuaternary1.8Man, mammals, 
Neogene24-1.8First hominids, horses, canine
Paleogene65-24tapirs, rodents
MesozoicCretaceous146-65marine invertebrates, marsupials, pterosaurs
Jurassic208-146Suaropods, birds, flowering plants
Triassic248-248First mammals, turtles, ichtyosaur
PaleozoicPermian280-248Amphibians and reptiles
Pennsylvanian325-280First reptiles, ferns, cockroaches
Mississippian360-325First winged insects
Devonian408-360Fish and land plants
Silurian438-408First jawed fishes, first insects
Ordovician505-438First primitive plants, corals, fungi
Cambrian575-500Trilobites,mollusks, brachiopods