Photo Gallery: Cretaceous Period
Tyrannosaurus rex arose during the Cretaceous period about 85 million years ago and thrived as a top land predator until the dinosaurs went extinct 20 million years later. This skeleton, on display in Chicago's Field Museum, is a cast of perhaps the world's most famous fossil: "Sue," a 67-million-year-old T. rex discovered in 1990 in South Dakota by field paleontologist Sue Hendrickson. It is the most complete, best preserved, and, at 42 feet (12.8 meters), the largest T. rex specimen ever found.
Awaiting renovations, dinosaur models of differing scales crowd a warehouse at Dinamation headquarters in Irvine, California. Some of these specimens would have seen their heyday during the Cretaceous period, including the familiar Tyrannosaurus and Triceratops, the Parasaurolophus (front right), and the flying pterosaur (top left). Others, like the stegosaurids (front center), were already extinct when the Cretaceous began.
This rendering of Cretaceous life shows the diverse range of dinosaurs that lived between 145 and 65 million years ago, including maiasaurs (front left); tarbosaurs (top right), and pterosaurs (top center). In the foreground are depicted the first flowering plants and one of the earliest mammal relatives, both of which developed during this period and went on to survive the dinosaur extinction at the end of the Cretaceous.
Pterosaurs, like these depicted gliding near an ancient sea, first arose during the Triassic period about 215 million years ago. They endured for 150 million years, colonizing every continent and evolving into more than 120 species. They died out along with the dinosaurs at the end of the Cretaceous.
This Sapeornis chaoyangensis fossil, housed in a Beijing museum, offers clues about the feeding habits of the Earth's early birds. The presence of gastroliths—stones ingested by animals to grind food in the gut—indicates that this species was a plant-eater. Other significant features include exceptionally long forelimbs, suggesting that Sapeornis, the largest known bird from the early Cretaceous, might have been able to soar.
Like their cousins the dinosaurs, pterosaurs stand out as one of evolution's great success stories. They first appeared during the Triassic period, 215 million years ago, and thrived for 150 million years before going extinct at the end of the Cretaceous period. Uncontested in the air, pterosaurs colonized all continents and evolved a vast array of shapes and sizes. This specimen, found in Italy, is Eudimorphodon ranzii, with a wingspan of about three feet (one meter) and 114 tiny teeth packed into its jaws.
Photograph by Jonathan Blair
From : Nationalgeographic