Dinosaurs: The Juurassic Period

The Jurassic Period is a time period were new dinosaurs were being discovered and found. It was about 199.6 to 145.5 million years ago. Some of the species that were found in the Jurassic Period are the Stegosaurus, Ceratosaurus, Brachiosaurus, and Allosaurus. Each dinosaur had their own characteristics for survival.

Shifting from the end of the Permian period 250 million years ago into the next era, the Triassic period occurred between 250 and 199 million years ago and was know for further diversifying life on land. After the Permian period, the Triassic period was largely successful in adapting and evolving, as the world was going through many changes. The land mass known as Pangea began its separation, which would be completed in the Jurassic period. The climate was relatively more severe during this time, with hotter summers and colder winters, but because of the warmer atmosphere, there were no polar ice caps at this time. Towards the center of Pangea, it was mostly a dry desert climate. As for life on earth, most of the marine life had been wiped

The Cambrian Period marks the beginning of the Paleozoic Era. This period gets its name from a place in Wales where the first examples of this type of ancient life was found. The period lasted for nearly 53 million years, from about 543 million years ago until 490 million years ago. The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears. It was once thought that the Cambrian rocks contained the

The Cretaceous period is a period of time within the Mesozoic Era lasting from 146 million years ago to 65.5 million years ago. It is one of three periods in the Mesozoic Era along with the Triassic and Jurassic periods. The Cretaceous period is well known for the amount of dinosaurs it had, and the event that put an end to the dinosaurs reign, the K-T mass extinction. During the K-T mass extinction, a huge asteroid hit earth and caused tons of dust to infiltrate the air. Only a small portion of dinosaurs died on impact Instead, the dust blocked out sunlight which caused plants to die. Without plants, many dinosaurs did not have a food source, so the died out. Carnivore dinosaurs, such as the Tyrannosaurus Rex, survived a little longer

The first dinosaurs were small, meat-eating animals that first arose over 200 million years ago. From such small beginnings evolved thousands of different species, including the largest animals ever to walk on Earth. At the Smithsonian, some of the most important dinosaurs known to science stand in our exhibit halls, from the ferocious Allosarus to eighty-foot Diplodocus. Learn more about our famous dinosaurs

Some 480 million years ago, way before the dinosaurs, the Ordovician period, was the period when plants were finally able to inhabit land. It lasted for 42 million years. Sea levels were very high during this time, which allowed the already present sea creatures to grow to even larger proportions.

The Triassic period from 252 million to 200 million years ago, saw the rise of reptiles and the first dinosaurs, the Jurassic period , from about 200 million to 145 million years ago, ushered in birds and

According to a live science, an article written by Mary Bagley, "The Cretaceous Period was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene extinction event dated at 65.5 million years ago"(Mary Bagley, LS). In the cretaceous period, the continent of Pangea was still breaking away from itself, forming what we now know as the seven world continents. In the many eras of dinosaurs, the cretaceous era was responsible for evolving some, but not all the dinosaurs from full land dinosaurs to some who were able to live both on land and in water, semi-aquatic carnivorous dinosaurs. This era had produced some of the dinosaurs that maybe us non- paleontologist are more familiar with like the all mighty tyrannosaurus rex or the long neck. Well let me tell you, there were a lot more dinosaurs than just those two. Although the tyrannosaurs rex was an enormous dinosaur, a bigger dinosaur was discovered in 1912, the Spinosaurus. This discovery would change peoples, kids, and paleontologists view on which dinosaur was bigger than the other. This semi-aquatic dinosaur, Spinosaurus, was much larger than the T-rex due to its sail like backbones that stuck out of its back. Furthermore, spinosaurus had a huge advantage that the tyrannosaurus-rex did not.

The dinosaurs appeared after the greatest mass extinction event occurred. This is known as the Permian-Triassic extinction. It has been estimated to have occurred around two hundred and fifty million years ago. (6) It is also known as the Great Dying with over ninety percent of species dying off, leaving the Earth essentially a wasteland. It led to the extinction of “57% of all families, 83% of all genera and 90% to 96% of all species. 53% of marine families, 84% of marine genera, about 96% of all marine species and an estimated 70% of land species, including insects.”(7) By the late-Permian, global temperatures were very hot, with them being the highest ever on the planet.

The end-Triassic or Triassic-Jurassic extinction event occurred around 200 million years ago is and thought by numerous have helped dinosaurs to be the dominant species on earth for 135 million years. It additionally finished life for generally 50% of all species that were available around then. Until this event, mammal like animals known as therapsids were much more than the ancestors of the dinosaurs, known as archosaurs. The dinosaurs survived better compared to the early proto-vertebrates, and this extinction event may have altogether tipped it to support them clarifies #########. Of the Big Five, the Triassic-Jurassic extinction event has the least number of current researches. Its cause stays under debate,

The dinosaurs were abundant at the end of the Cretaceous Period. There was no gradual decline of the dinosaurs. During the time where there was no light, footprints of land dinosaurs were discovered. The footprints showed that the dinosaurs were running away from something, more specifically a tsunami. Scientists also found fossilized fish. The fish’s gills were filled with the glass created from the explosion. Because the fish’s gills were filled with glass, means that the fish were alive and swimming and inhaled the glass particles. The fish were the first known victims of the impact. Fish were crushed under the sediment that the tsunamis picked up and brought towards land such as the Hells Creek Formation. After the whole ordeal finished, there were a few dinosaurs still on the earth. The living dinosaurs were few and far between. Even though a few dinosaurs were still alive, more than ninety percent of all of them died in the inescapable night that followed the impact. It is believed that the only reason some smaller dinosaurs survived is because they lived in habitable areas that did not suffer extreme cooling like those that inhabited the equatorial

During this time, there were two major animal groups that settled on land. There were tetrapods, who were the first vertebrates to walk the land and the first terrestrial arthropods, which included wingless insects and early arachnids. The Devonian period was also known as the Ages of Fishes, because there was an abundance of diverse fishes at that time. The first fishes didn’t have jaws and their support structure was made of cartilage, later they developed jaws, gills, and fins and the first sharks and bony fish appeared. Most of the land masses formed two neighboring supercontinents named, Gondwana and Euramerica. Water covered the rest of Earth. Plants started covering the land where they developed vascular tissues which allowed them to

“The Tertiary Period began 65 million years ago and ended just 1.8 million years ago. It was made up of 5 different epochs.” “Paleocene epoch that was 65 to 54 million years ago.” “ Eocene epoch that was 54 to 38 million years ago.” “ Oligocene epoch 38 to 24 million years ago.” “ Miocene epoch 24 to 5 million years ago.” “Pliocene epoch 5 to 1.8 million years ago.”

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.

The Staurikosaurus was one of the earliest dinosaurs to walk the earth that was discovered in modern times. It was a tiny theropod that was extant in the middle Triassic period of the Mesozoic era. The timeline of its existence is judged at about 230 to 220 million years ago.