Saturday 19 May 2012

Prehistoric Animals : Ornithopod Dinosaurs




Ornithopod Dinosaurs
With some of the most advanced chewing apparatus ever developed by a reptile, ornithopod dinosaurs became a most successful group of herbivorous dinosaurs. They rapidly became a prominent feature on North America's Cretaceous landscape, until they were wiped out by the famous Cretaceous-Tertiary, or K-T, extinction event. Early ornithopods were only about a metre long and could probably run very fast on their hind legs. They evolved to become as large as some of the mighty sauropods, walking and grazing on all four legs, but still using the hind legs for running and reaching up into trees. Notable ornithopods include the duck-billed hadrosaurs and, of course, iguanodon.
Scientific name: Ornithopoda
Common names:bird feet

Ornithopods ( /ɔrˈnɪθɵpɒd/) or members of the clade Ornithopoda (/ɔrnɨˈθɒpədə/) are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American landscape. Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by a reptile, rivaling that of modern mammals like the domestic cow. They reached their apex in the duck-bills, before they were wiped out by the Cretaceous–Paleogene extinction event along with all other non-avian dinosaurs. Members are known from all seven continents, although the Antarctic remains are unnamed, and they are generally rare in the Southern Hemisphere.

Prehistoric Animals : Horned Dinosaurs : Ceratopsia



Horned Dinosaurs

Speculation continues over the function of the wicked looking horns and grand neck frill of the larger ceratopsians such as Triceratops. Were they for protection, display or even to control body temperature? The earliest horned dinosaurs were quite small and got about on two legs. The four legged giants that characterise the group came later. Fossil evidence suggests horned dinosaurs originated in what's now Asia during the Cretaceous period, spreading out and thriving as herbivores. Many of the species are recognised from their skulls, which seem to be the part of a ceratopsian skeleton most likely to be preserved.

Ceratopsia or Ceratopia ( /ˌsɛrəˈtɒpsiə/ or /ˌsɛrəˈtoʊpiə/; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7 million years ago. The last ceratopsian species became extinct in the Cretaceous–Paleogene extinction event, 65.5 million years ago.

Early members of the ceratopsian group, such as Psittacosaurus, were small and bipedal animals. Later members, including ceratopsids like Centrosaurus and Triceratops, became very large quadrupeds and developed elaborate facial horns and frills extending over the neck. While these frills might have served to protect the vulnerable neck from predators, they may also have been used for display, thermoregulation, the attachment of large neck and chewing muscles or some combination of the above. Ceratopsians ranged in size from 1 meter (3 ft) and 23 kilograms (50 lb) to over 9 meters (30 ft) and 5,400 kg (12,000 lb).

Triceratops are by far the best-known ceratopsians to the general public. It is traditional for ceratopsian genus names to end in "-ceratops", although this is not always the case. One of the first named genera was Ceratops itself, which lent its name to the group, although it is considered a nomen dubium today as its fossil remains have no distinguishing characteristics that are not also found in other ceratopsians.

Scientific name: Ceratopsia
Common names:horn face

Prehistoric Animals : Ceropod Dinosaurs



Ceropod Dinosaurs
Ceropod dinosaurs were all plant-eaters and include the horned and duck-billed dinosaurs. The secret of their success was in their teeth. These were much more efficient at grinding up plant food than your typical dinosaur's dentition, so cerapods were able to extract more nutritional value from their food and tackle plants that others found too tough to digest. It wasn't until big herbivorous mammals evolved that such efficient chewing teeth were seen again on Earth.
Scientific name: Cerapoda
Common names:horn foot

Prehistoric Animals : Bird-hipped Dinosaurs


Bird-hipped Dinosaurs

Bird-hipped dinosaurs derive their name from the shape of their pelvis, which resembles that of modern birds, whose pubis points to the rear of the animal. Unexpectedly, birds did not evolve from these dinosaurs, but from the lizard-hipped dinosaurs, since this shape of pelvis has evolved more than once. Another distinguishing characteristic of the bird-hipped dinosaurs was a horny beak, which they used to crop plants, much like a horse or deer uses its front teeth today. Duck-billed dinosaurs, horned dinosaurs and armoured dinosaurs were all of the bird-hipped variety.

Scientific name: Ornithischia
Common names:Bird-hipped

Prehistoric Animals : Lizard-hipped Dinosaurs


  
Lizard-hipped Dinosaurs

The earliest known dinosaurs, lizard-hipped dinosaurs first appeared in the mid Triassic. As well as these first dinosaurs, the order includes all the carnivorous dinosaurs and one group of herbivores - the sauropods and their close relatives. The name 'lizard-hipped' comes from the shape of their pelvis, in which the pubis points towards the front of the animal. Birds are descended from this group of dinosaurs.

History of life on Earth :Prehistoric animals




Dinosaurs
DinosaursDinosaurs were the dominant land animals for 160 million years, making them one of the most successful groups of animals ever. The name dinosaur translates as 'terrible or wondrous lizards' and they certainly evolved in a diverse range of sizes and shapes, from the gigantic plant-eating sauropods to the quick meat-eating tyrannosaurs. They also sported an impressive array of body modifications including horns, scales and crests. So far, the remains of over 1,000 different dinosaur species have been identified from fossils though technically, birds are feathered dinosaurs, meaning dinosaurs are not really extinct at all.

Prehistoric Animals
Dinosaurs Tyrannosaurus Diplodocus Ichthyosaur Woolly mammoth Neanderthal Pterosaur Ammonite History of life on Earth

Prehistoric Animals
Dinosaurs, Tyrannosaurus, Diplodocus, Ichthyosaur,Woolly mammoth, Neanderthal Pterosaur Ammonite
Big Five extinctions
Permian–Triassic extinction event Cretaceous–Tertiary extinction eventGeological time periods
Jurassic TriassicMass extinction theories
Impact event Flood basaltAncient Earth habitats
Snowball Earth Coal fore