Portal:Dinosaurs

The Dinosaur Portal

Introduction

Herrerasaurus ischigualastensis
(a carnivorous basal dinosaur)

Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.

Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 11,000 living species, are among the most diverse groups of vertebrates. Using fossil evidence, paleontologists have identified over 900 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species (birds) and fossil remains. Through the first half of the 20th century, before birds were recognized as dinosaurs, most of the scientific community believed dinosaurs to have been sluggish and cold-blooded. Most research conducted since the 1970s, however, has indicated that dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction. Some were herbivorous, others carnivorous. Evidence suggests that all dinosaurs were egg-laying, and that nest-building was a trait shared by many dinosaurs, both avian and non-avian. (Full article...)

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Parasaurolophus (meaning 'near crested lizard') was a genus of ornithopod dinosaur from the Late Cretaceous Period of what is now North America, about 76-73 million years ago. It was a herbivore that walked both as a biped and a quadruped. Three species are recognized: P. walkeri (the type species), P. tubicen, and the short-crested P. cyrtocristatus. Remains are known from Alberta (Canada), and New Mexico and Utah (United States). It was first described in 1922 by William Parks from a skull and partial skeleton in Alberta.

Parasaurolophus is a hadrosaur, part of a diverse family of Cretaceous dinosaurs known for their range of bizarre head adornments. This genus is known for its large, elaborate cranial crest, which at its largest forms a long curved tube projecting upwards and back from the skull. A similar crest is found on Charonosaurus from China, which may have been its closest relative. The crest has been much discussed by scientists; the consensus is that major functions included visual recognition of both species and gender, acoustic resonance, and thermoregulation. It is one of the rarer duckbills, known from only a handful of good specimens. (see more...)

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Camarasaurus skull at the Smithsonian Museum of Natural History.

Photo credit: Commons:User:Quadell

Did you know...

...that Atlascopcosaurus and Qantassaurus are two Australian dinosaurs named after businesses?
...that a specimen of Brachylophosaurus nicknamed 'Leonardo' was found fully articulated and wrapped in impressions of its skin?