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Dinosaurs are a diverse group of reptiles [note 1] 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.
- Edmontosaurus
Edmontosaurus (/ ɛ d ˌ m ɒ n t ə ˈ s ɔːr ə s /...
- Dracohors
Dinosauromorpha is a clade of avemetatarsalians (archosaurs...
- Dinosaur (Disambiguation)
Places. Dinosaur, Colorado, a town in the United States;...
- Ceratosauria
Since C. nasicornis was the only other dinosaur discovered...
- Phylogenetic Nomenclature
Definitions. Phylogenetic nomenclature associates names with...
- List of Dinosaur Genera
There is no official, canonical list of all non-avian...
- Nyasasaurus
Nyasasaurus (meaning "Lake Nyasa lizard") is an extinct...
- List of dinosaurs
The following is a list of dinosaurs. Some of them, such as...
- Edmontosaurus
- Dinosaur Features
- Types of Dinosaurs
- Dinosaur Origins and Evolution
- Adaptive Radiation
- Life Style
- Extinction
- Related Pages
- Books
Dinosaurs are so varied that it is not easy to find what they all share. A reasonable list would include many features of the skeleton which are not familiar to the general reader. Dinosaurs were, at the start, small and bipedal: they walked on their hind legs. They laid eggs in nests, and included both carnivores and herbivores. We now know that b...
Dinosaurs are united by at least 21 traits in their skulls and skeletons. These common characters (called 'synapomorphies') are the reason palaeontologistsare sure dinosaurs had a common origin. However, when definite dinosaur fossils appear (early in the Upper Triassic), the group had already split into two great orders, the Saurischia, and the Or...
Archosaurs
The Archosaurs evolved into two main clades: those related to crocodiles, and those related to dinosaurs. 1. Archosauria 1.1. Pseudosuchia: clade of the crocodilesand their relatives. 1.2. Avemetatarsalia: clade of the dinosaurs, pterosaurs, birds and relatives. 1.2.1. Aphanosauria (small group in middle Triassic) 1.2.2. Ornithodira: clade of the pterosaurs and dinosaurs. 1.2.2.1. Pterosaurs 1.2.2.2. Dinosaurs
Earliest dinosaurs
The first known dinosaurs were bipedal predatorsthat were one to two metres long. The earliest confirmed dinosaur fossils include the saurischian ('lizard-hipped') dinosaurs Herrerasaurus 230–220 mya, Staurikosaurus possibly 230–225 mya, Eoraptor 231.4 mya, and Alwalkeria 230–220 mya. Saturnalia, 232–225 mya, may be a basal saurischian or a prosauropod. The others are basal saurischians. Among the earliest ornithischian ('bird-hipped') dinosaurs is Pisanosaurus 230–220 mya. Although Lesothosa...
Dinosaurs were a varied group of animals. Adaptive radiation happened. This let them live in many ecological niches. Paleontologists have identified over 500 different genera and 1,000 species of non-avian dinosaurs.Their descendants, the birds, number 9,000 living species, and are the most diverse group of land vertebrates. The largest dinosaurs w...
Locomotion
Dinosaurs were primitively bipedal: their probable ancestors were small bipedal Archosaurs. The date of the early dinosaur genus Eoraptor at 231.4 million years ago is important. Eoraptor probably resembles the common ancestor of all dinosaurs; its traits suggest that the first dinosaurs were small, bipedal predators. The discovery of primitive, pre-dinosaur, types in Middle Triassic stratasupports this view. Analysis of their fossils suggests that the animals were indeed small, bipedal preda...
Warm blooded
A major change in outlook came in the 1960s, when it was realised that small theropods were probably warm-blooded.The question of whether all theropods or even all dinosaurs were warm blooded is still undecided. It is now certain (from fossils discovered in China: see Jehol biota) that small theropods had feathers. This fits well with the idea that they were warm-blooded, and that the origin of birdscan be traced to a line of small theropods.
Activity
Warm blooded animals have a high metabolic rate (use up food faster). They can be more active, and for longer, than animals who depend on the environmentfor heating. Therefore, the idea of warm-blooded dinosaurs insulated by feathers led to the idea that they were more active, intelligent and faster runners than previously thought. Main-stream palaeontologists have followed this view for small theropods, but not for larger herbivores. Since we know that the size of a Stegosaur's brain was abo...
The extinctions at the end of the Cretaceous were caused by a catastrophic event: a massive meteorite hit the Earth (the Chicxulub impact). We now know where it hit: in the Yucantan peninsulain what is now Mexico. Several other impact craters, and massive volcanic activity in the Deccan Traps in India, have been dated to about the time of the extin...
For "dinobirds", see Origin of birdsBakker, Robert T. 1986. The Dinosaur Heresies: new theories unlocking the mystery of the dinosaurs and their extinction. New York: Morrow. ISBN 0-688-04287-2Farlow J.O. and Brett-Surman M.K. (eds) 1997. The Complete Dinosaur. Indiana University Press. ISBN 0-253-33349-0Holtz, Thomas R. Jr. 2007. Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House. ISBN 978-0-375-82419-7Iggulden, Hal; Iggulden, Conn (2007). "Dinosaurs". The Dangerous Book for Boys. New York: HarperCollins. pp. 30–34. ISBN 978-0061243585.Tyrannosaurus (/ t ɪ ˌ r æ n ə ˈ s ɔː r ə s, t aɪ-/) is a genus of large theropod dinosaur. The type species Tyrannosaurus rex (rex meaning "king" in Latin), often shortened to T. rex or colloquially T-Rex, is one of the best represented theropods.
The Dinosaur Portal. 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.
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While it is structured so as to reflect evolutionary relationships (similar to a cladogram ), it also retains the traditional ranks used in Linnaean taxonomy. The classification has been updated from the second edition in 2000 to reflect new research, but remains fundamentally conservative.
