Essay Example on Precambrian era - the time oxygen begin to accumulate in the atmosphere









Stuti Ray It all started 454 million years ago when the origin of the earth occurred 350 million years ago the first clear evidence of life was bacteria This was also known as the Precambrian era which was also the time oxygen begin to accumulate in the atmosphere After this it was the Paleozoic era which was 542 million years ago when different types of life forms were flaring up but the Invertebrates dominant were the main Some example is worms jellyfish trilobite and etc This was the era when lots of different creates were formed like insects amphibians and first ever mammal like reptiles First plants and forest were also formed in this era It was a base for what we have now The Mesozoic era which was 251 million years ago which was when there was first dinosaurs fist egg mammals birds and etc But later in the era birds were taking over by replacing the dinosaur It was also the time when the first flowering plants were formed with lots of other forest conifers and cycads The last and the latest era was Cenozoic which is also known as the age of the mammals About 34 mya ago monkeys apes prosimians flourish and other families evolve with the savanna grazing animals Later in the tertiary period in the Pliocene epoch which was 5 million years near human species and other modern mammals grew 

Then came recent ice ages which were 2 million years ago in the Pleistocene epoch The final and last epoch in the Quaternary period was about 11 700 years ago when modern humans were living and present climate was formed The sudden ancestors of the humans were part of the genus Australopithecus The Australopithecines was in between of the apes and the people Apes do not have any tail and that's the reason they are different than other primates Both the people and the apes belong to the same biological group known as the Hominini All the people from the past and present also with australopithecines are hominins Every one of us shares similar ape ancestors which were in Africa According to the article Discovery of Early Hominids In 1924 Raymond Dart the Australian composition professor at the University of Witwatersrand acquired a fossil skull that was found by the limestone quarry at the Taung https www2 palomar edu anthro hominid australo_1 htm Raymond Dart was the first person ever to discover this type of evidence and it took him almost 73 days to engrave the skull from the stone matrix that was around it It also took him 4 years if extra time to free the jaw and the fossilized brain but long before that he knows the purpose of what he has discovered After looking at the skull and analyzing it he discovered that the species is intermediate between the apes and humans because of its small sized brain After observing the hole in the skull from were the spinal cord goes through faced downward and was at the center of the skull and the canine teeth which were little short meant that the Taung child must have been bipedal 

According to the Later in the 1920 s paleoanthropologist refused Dart s claim that the Australopithecus africanus was in between apes and humans but until later in 1940 s it was accepted C K Brain was another great South African paleoanthropologist who researched Swartkrans cave very carefully another time in between 1965 and 1983 He discovered lots of bone fragments with 130 individual hominins were recuperate by Brin The bones were from the australopithecines Paranthropus and from genus Homo Early hominid fossils were discovered by Mary and Louis Leakey from Olduvai Gorge through there expeditions Using the new potassium argon dating technique it was discovered that the fossil was 1 75 million years ago While in 1974 Donald Johanson who found a complete skeleton of the adult female who was an ancient species of australopithecine There is so much evidence found through skulls and skeletons discovered by different people Those were some people with great discoveries by using different types of fossil evidence Over the time bones of early hominins have evolved creating modern humans 

There were so many features function shapes and other things have changed over time creating us or the human beings 3 million years ago most hominins were mostly as smooth as bipedal locomotion as humans are today Bipedal is when one uses two legs to walk Like individuals but not at all like primates the bones of their pelvis or hip part were abbreviated from upper body down to the bottom and bowl shaped This made the pelvis more firm for weight bolster when standing upright or walking bipedally The longer primate pelvis is adjusted for quadrupedal motion Hominin leg bones were too much more compared to our own than to those of primates Also over time early hominin legs developed longer and grow much stronger than their arms Hominin feet become longer and grew arches for more systematic to be able to carry the body weight Their hands got used to grabbing holding and doing the task such as eating food and carrying tools One of the disadvantages of walking bipedally on the land is that it made it harder to climb and jump through the trees but there are so many other advantages Australopithecines comparing to humans they had many features below the neck or shoulder that was almost the same Modern humans have the bigger brain than them Hominin faces were longer they had long pointy jaw giant molar teeth with fat enamel and their front teeth were small The modern humans the jaw muscles are small and joined on the skull in temple part jaw and teeth are mostly small and the faces are bit vertical

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