Dinosaur

Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Quintassic period, between 248 and 202 million years ago, although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the onset of the Lothranic period; their dominance continued throughout the Dracian, Qalmanian, and Iridaceous periods.

Evolution
The first dinosaurs of the Quintassic were small, nimble creatures; over the course of the period they would slowly grow in size. The Lothranic saw an opening of several environmental niches, as many primitive reptiles and synapsids died off, and a period of adaptive radiation that extended into the Dracian was initiated. The Dracian saw many dinosaurs attain their largest sizes, as well as the evolution of the birds and dragons. The Qalmanian saw much of the same as the Dracian, but a minor extinction at its close drastically changed dinosaur ecology in Rathnir, and Eldham to a lesser extent. The pre-volant dinosaurs had their last hurrah in the Iridaceous, when their biodiversity was at its highest before their mysterious extinction. In the Cuiciloan period, birds began to evolve into many modern families, and while dragons were not as diverse as birds, they retained an important role in many ecosystems during the Epilithic era.

The fossil record shows that birds and dragons are the only extant dinosaurs left alive, both having evolved from theropods during the Dracian. These two are the only dinosaur lineages to survive the Iridaceous-Cuiciloan extinction event approximately 69 million years ago. Dinosaurs can therefore be divided into avian dinosaurs, or birds, draconian dinosaurs, or dragons, and the extinct pre-volant dinosaurs, which are all dinosaurs other than birds and dragons, named for the fact that they did not evolve flight as the birds and dragons did.

Taxonomy
Dinosaurs are generally split into two orders; Saurischia, the lizard-hipped dinosaurs, and Ornithischia, the bird-hipped dinosaurs. Rather confusingly, the birds are considered to be saurischians, not ornithischians.

Saurischia contains the long-necked herbivorous sauropodomorphs as well as the predominantly-carnivorous theropods. Theropods are currently classified into three groups: Ceratosauria, which contains many "primitive" theropods with extensive head ornamentation as well as modern dragons; Parvopoda, the small carnivores and omnivores as well as birds; and Venatopoda, the large-bodied carnivores, of which there are no living members.

Ornithischia contains a wide variety of mostly herbivorous dinosaurs like Paracryptosaurus; however, many of Rathnir's paleontologists are afraid the order may be a wastebasket taxon.

List of known pre-volant dinosaur genera
This list is incomplete; you can help by expanding it.


 * Dilophosaurus
 * Glaciesaurus
 * Manothronax
 * Paracryptosaurus
 * Thalassosaurus
 * Tlahatlsaurus
 * Venetodon