The Triassic Period

About 20 million years after Pappochelys, we began to see a more similar looking ancestor to the turtle, the Odontochelys semitestacea. O.semitestacea was roaming the planet in the Late Triassic era in modern day China. Odontochelys differed a lot from modern turtles. Modern day turtles possess a horned like beak without any teeth present in their mouth, while Odontochelys fossils showed that teeth were found embedded in their upper and lower jaws. One of the most interesting features of turtles, both modern and prehistoric, are their shells that formed an armored protective casing over its body. Odontochelys only possessed the plastron (the bottom portion of a turtle's armor) and it had yet to develop a solid carapace. Instead of a carapace,

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.

During the Cambrian Period there was an explosion of life forms. Most of these were in the water. Many animals with no backbones lived in the shallow seas. These animals were invertebrates.

It is most likely that a simultaneous occurrence of the different global environmental changes was responsible for ending the Permian period, and the lives of 96% of species. Each environmental issue is a major geological event, and amplified the other events, leading to catastrophic environmental situation, in which barely any life could survive.

out (Bagley, 2014). This was the closer of the Permian-Triassic period. This means that the rest

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

Around 300 million years ago, Pangea existed during the late Paleozoic and early Mesozoic eras and approximately 120 million years ago, Pangea split into two smaller sections called Gondwana and Laurasia. Gondwana formed prior to Pangea , and later on became part of it. However, after the break-up of Pangaea, Gondwana possessed most of the regions in today’s Southern Hemisphere, including Australia, Africa, Antarctica and South America. Similarly, around 180 million years ago, Gondwana also began to split up. Africa and South America beginning to drift away, leaving just India, Madagascar, Antarctica and Australia and about 40 million years later, India and Madagascar broke off. Leaving just Antarctica and Australia. Correspondingly, approximately 85 million years ago Australia separated from Antarctica, finally becoming its own continent.

Towards the center of the period the atmosphere ended up hotter and milder, the ice sheets subsided, and the mainland insides wound up drier. A significant part of the inside of Pangea was presumably bone-dry, with incredible regular vacillations (wet and dry seasons), due to absence of the directing impact of close-by waterways. This drying inclination proceeded through to the late Permian, alongside substituting warming and cooling

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

Another was the formation, about 3 million years ago, of the Isthmus of Panama, which connected North and South America and diverted the oceans’ circulation t a more northward pattern. Since the first northern-hemisphere glaciers formed, 2.6 million years ago, the polar ice caps have expanded and contracted in response to variations in the Earth’s orbit around the Sun, causing cold spells alternating with warmer periods, like the one we live in now. There is no reason to believe that another Ice Age won’t come. In the past, warm cycles lasted about 10,000 years, and it’s been that long since the last cool period. Human-made pollutants may also have an effect on the Earth’s climate cycles. The Pleistone period was between 2 million and 10,000 years ago. This was the time of the “Ice Ages,” when climates alternated between conditions similar to those of the present day, and periods when great glaciers spread over large parts of the Earth. Between 15,000 and 10,000 years ago, many large mammals, including saber-toothed cats, ground sloths, mammoths, and mastodons, became

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 fifth, and one of the largest and most well known extinctions in Earths history was the Cretaceous period, where many species, including the dinosaurs, pterosaurs, and large marine reptiles, disappeared. This period was widely known as the K-T period, K being the traditional abbreviation for the Cretaceous Period derived from the German name Kreidezeit, and T being the abbreviation for the Tertiary Period (a historical term for the period of time now covered by the Paleogene and Neogene periods). It was a relatively warm climate and had high global sea levels. The oceans and seas were populated with now extinct marine reptiles, ammonites and rudists, and the land by dinosaurs. At the same time, new groups of mammals and birds as well as flowering plants appeared. The early part of the Cretaceous showed a cooling trend that had been

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,

Jurassic is a period of time with Dinosaurs, rodents and birds. There were also island seas consisting of sharks, sea monsters and blood-red planktons. The existing plants in that period were cycads, ferns and conifers. The Mesozoic era was about 245 million years ago to 65 years ago, so it almost lasted about 180 years in total. The Mesozoic era is divided into three periods of Triassic, Jurassic and Cretaceous. Mesozoic era means middle animals and it is the era, which the word’s fauna has changed from what is in the Paleozoic era and the most famous organisms of this era are dinosaurs. In the Mesozoic era, the extinction of more than 90 percent of species in the earth was observed and the reason behind it was mostly volcanic eruptions and climate changes. On the other hand, this era had massive changes that represented ecological niches and rise to new creatures such as rodent-size mammals and first dinosaurs. In Triassic, which was the first period of Mesozoic, the mammals and first dinosaurs existed. Later than that, the second period was Jurassic, which giant shaped dinosaurs and other kinds of dinosaurs were developed. Besides that the first flowering plants and primitive birds, with long teeth appeared in that era as well.

Rapid climate change also ends up on the suspect list of possible dinosaur extinction events. During the latter part of the Cretaceous Period continents broke up causing volcanoes to erupt and fill the sky with gas and ash resulting in a drastic climate change (“Dinosaurs Climate Change and Biodiversity”). The shifting of continents changed the Earth’s landscape, altering weather patterns and overall climate (“Dinosaur Extinction Theories”). Also, over a long period of time, climate gradually changed. Ocean habits changed, temperatures grew much more extreme causing scorching summers and frigid winters (Norell, Dingus, and Gaffney). Radical temperature changes like these led to a green-house effect, making life for the dinosaurs a lot