More dinosaur species from fossil record!!
Scientists at the University of Pennsylvania have found more dinosaur species. They made a statistical analysis of an exhaustive database of all known dinosaur genera. They knew 29% of all dinosaurs. It then used this data to generate the total number of genera preserved in fossil record.
Scientists will eventually discover 1844 dinosaur genera --- at least 1300 more than 527 recognised today.
The various species appeared at different times, and not all overlapped. The shape of the teeth reveal whether a given dinosaur was a carnivore or herbivore. Dinosaurs are classified as either ornithischians or saurischians, based on pelvic girdle structure. Most had a long tail, which they held straightout, apparently to maintain balance. Most, if not all, were egg layers.Some were probably warm-blooded. Dinosaur fossils have been found on every continent, including Antarctica. Most types of dinosaurs flourished until late in the Cretaceous Period (65 million years ago), then disappeared within the next million years. Two theories for the cause of this mass extinction, following some 140 million years of existence, are that mountain-building cycles altered habitat and changed climate or that an asteroid hit the Earth, resulting in immense dust clouds that blocked sunlight for several years. Birds are thought to be living descendants of the dinosaurs.
The Jurassic period is the interval of geologic time, 206–144 million years ago, that is one of the three major divisions of the Mesozoic Era, preceded by the Triassic Period and followed by the Cretaceous.
During the Jurassic, Pangea began to break up into the present-day continents. Marine invertebrates flourished, and large reptiles dominated many marine habitats. On land, ferns, mosses, cycads, and conifers thrived, some developing flowerlike structures in place of cones. The dinosaurs rose to supremacy on land, and by the end of the Jurassic the largest species had evolved. Archaeopteryx, the first primitive bird, appeared before the end of the period. Early mammals, tiny shrewlike creatures that appeared near the close of the preceding Triassic, managed to survive and evolve.
Carnosaurs are any of the large carnivorous dinosaurs, a branch of theropod dinosaurs that evolved into predators of large herbivorous dinosaurs.
Carnosaurs were massive animals with short necks, large skulls, and wide, gaping mouths equipped with formidable teeth. They walked on two legs. Tyrannosaurs were the largest of all carnosaurs. The carnosaurs became extinct at the end of the Cretaceous period (65 million years ago).
Saurischians are any “lizard-hipped” dinosaur species (order Saurischia), with hip bones arranged like those of modern reptiles, the pubis bone pointed forward and down.
The order includes all carnivorous and some giant herbivorous dinosaurs. Saurischians evolved from small bipedal dinosaurs called thecodonts; they first appeared in the Late Triassic epoch (227–206 million years ago). The order consists of three suborders: theropods, sauropods, and staurikosaurs (suborder Staurikosauria). Staurikosaurs, known only from the incomplete remains of a few species, seem to have been medium-sized flesh-eaters similar to the theropods.
Allosaurus are large carnivorous dinosaur of a group similar to the tyrannosaurs, found as fossils primarily in Late Jurassic rocks of North America.
It weighed 2 tons (1,800 kg) and grew to 35 ft (10.5 m) long. Its well-developed tail, half of its total body length, probably functioned as a counterbalance for the body. Allosaurus walked on its two hind limbs and probably used the much smaller forelimbs for grasping. Equipped with powerful, flexible jaws, allosaurs likely preyed on medium-sized dinosaurs; they were possibly scavengers that hunted in groups. Some related allosaurs (Giganotosaurus, Carcharodonotosaurus) may have been larger than Tyrannosaurus rex.
Diplodocus is a genus of sauropod dinosaur found as fossils in Late Jurassic rocks of North America and related to Apatosaurus.
Diplodocus and its relatives (diplodocids) were some of the longest land animals that ever lived, some approaching 100 ft (30 m). It had along neck and extremely small brain and skull. Most diplodocids weighed about 30 tons, and some as much as 80 tons. It was formerly thought that Diplodocus may have spent a good deal of time in water, but fossil evidence indicates it moved freely on land, where it apparently fed on soft vegetation. It may be the most commonly displayed dinosaur.