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Dinosaurs
Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. Non-avian dinosaurs became extinct 65 million years ago (Mya) at the end of the Cretaceous period. Dinosaurs are known from both fossils and nonfossils including fossilized bones, feces, trackways, gastroliths, feathers, impressions of skin, and internal organs. Since the first dinosaur was recognized win the 19th century, their mounted skeletons have become a major attraction at museums around the world. Dinosaurs have become a part of world culture, and have remained consistently popular, especially among children. They have been featured in bestselling books and blockbuster films like Jurassic Park, and new discoveries are regularly covered by the media. The term is also used informally to describe any prehistoric reptile, like the pelycosaur Dimetrodon, the winged pterosaurs, and the aquatic ichthyosaurs, plesiosaurs, and mosasaurs. The on-going dinosaur renaissance started in the 1970s, and was triggered in part by John Ostrom's discovery of Deinonychus: an active, vicious predator which may have been warm-blooded (homeothermic), in marked contrast to prevailing image of dinosaurs as sluggish, cold-blooded reptiles. Vertebrate paleontology has also become global, with major new discoveries in previously unexploited regions, including South America, Madagascar, Antarctica, and most significantly the discovery of amazingly well-preserved feathered dinosaurs in China, which have further solidified the link between dinosaurs and their living descendants, the 9,000+ species of modern birds. The widespread application of cladistics, which rigorously analyzes the relationships between biological organisms, has also proved tremendously useful in classifying dinosaurs, which are still known from a spotty fossil record. Evolution of DinosaursDinosaurs diverged from their archosaur ancestors approximately 230 million years ago during the early Triassic period, roughly 20 million years after the Permian-Triassic extinction event wiped out an estimated 95 percent of all life on Earth. Radiometric dating of fossils from the early dinosaur species Eoraptor establishes its presence in the fossil record at this time. Paleontologists believe Eoraptor resembles the common ancestor of all dinosaurs if this is true, its traits suggest that the first dinosaurs were small, bipedal predators. Also among the earliest dinosaurs was the primitive Lagosuchus; Saltopus, which was barely larger than a human hand, appeared slightly later. The first few lines of primitive dinosaurs diversified rapidly through the rest of the Triassic period; dinosaur species quickly evolved the specialized features and range of sizes needed to exploit nearly every terrestrial ecological niche. During the period of dinosaur predominance, which encompassed the ensuing Jurassic and Cretaceous periods, nearly every known land animal larger than 1 meter in length was a dinosaur. The Cretaceous-Tertiary extinction event, which occurred approximately 65 million years ago at the end of the Cretaceous period, caused the extinction of all dinosaurs except for the line that had already given rise to the first birds. Other diapsid species related to the dinosaurs also survived the event. Links about Dinosaurs InformationDinosaurs Time Machine for Kids PrehistoricPlanet.com K-Paleo: Fossils, Dinosaurs, Museums and More What Killed The Dinosaurs? Hadrosaurus.com Dinosauria On-Line Dinosaur DIGS ZoomDinosaurs.com New Scientist Special Report on Dinosaurs Dinosaurs and Evolution Dinosaur Museum in Blanding, Utah Dinosaur FAQ What's a Dinosaur Scholastic.com: Dinosaurs Discovering Dinosaurs Dinosaurs. Roadside America Dinosaurs: Science Or Science Fiction University of California Museum of Paleontology Dinosauria: Systematics Dinosaur Eggs Dinosaur Evolution Responses to dinosaur-lung claims by Jeff Poling Demise of the "Birds are Dinosaurs" Theory by Richard L. Deem M.Sc. Who Dunnit to the Dinosaurs? Impossible Dinosaurs Journal of Dinosaur Paleontology - Archaeopteryx, Ancient Birds, & Dinasaur-Bird Relationships... Dinosauromorpha: Overview |
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Palaeontologia Electronica - These annotated web sites are indexed, where feasible, by fossil group, by geologic age, by viewpoint, and by the country/town/institution/originator. (online technical journal) |
Dinosaurs for K-12 - For general information about dinosaurs, see also Dinosaur Resources for K-12.. Other related pages include Paleontology and Paleontologists. |
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