The Fossil Record

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The Fossil Record

Fossils are well-preserved remains or traces of remains of rocks. A fossil can keep whole or part of organism. The fossils of dinosaurs have been found in China and they show that the dinosaurs lived about one hundred million years ago. The dinosaur fossils were discovered in arid regions, a place without vegetation or sufficient rainfall to damage the evidence. The location where these fossils are found have silty rocks made by the compression of silt and clay layers over a certain period (Knaust, 2017). Index fossils are the kind of fossils that are spread widely and are mainly utilized in the process of dating different fossils situated in similar sedimentary layers. Ammonites, which is common in the Mesozoic Era (245 to 65 mya), is one example of index fossils (Knaust, 2017). The other type include Brachiopods that was discovered in the Cambrian era (540 to 500 mya).

There are many ways that fossils can form. Firstly, fossils may be formed through natural cast. This happens when all the tissues or bones are washed away by running water leaving an impression of sediments. In most instances, the cracks left by the streams of water may be filled with minerals, which would form organism’s original size and shape (Knaust, 2017). Amber preserved is another process of fossil formation. In this method, organisms get stuck on trees to form fossils. After the tree resin hardens, and is buried in the soil, fossils are formed. An example of this type of fossil includes birds’ nests (Knaust, 2017). Finally, permineralization is another method of fossil formation where by the minerals carried away by streams fill cellular cracks of plants and animals. After the minerals in the water have crystallized, they create an animal or plant like shape. The living organisms do not form fossils because most of them are not protected after death and immediately die or decay (Knaust, 2017).

 Part 2: The Extinction of the Dinosaurs

Dinosaurs vanished from the face of the earth approximately sixty-six million years ago. In the present situation, their remains are the only source that offers proof concerning their survival, structure, period that they lived. The earth's environmental past is categorized into numerous time periods. These periods are formed from certain events such as significant ecological alteration or animal death. Considering the case of dinosaurs, their disappearance is amid the era of Cretaceous and Tertiary. The K-T boundary has a comprehensible division line that is always clearly seen in places such as Gubbio, Italy that limestone formation, which is by virtue of acknowledgment of formerifera stopped suddenly. Researchers, on assessing this situation, discovered that the focus of iridium was concentrated on the top layer of limestone. It shows that the boundary was formed after an asteroid fell on earth. This also contributed to the dinosaurs’ extinction. Besides, to confirm the occurrence of asteroid shower, several other places were assessed and it was discovered that there were remains of the meteor impact and the remains were formed on places which also had dinosaurs’ fossils. These remains were recognized by concentration of iridium. Below KT boundary, researchers also found Mud stone and dinosaur fossils such as Euoplocephalus were discovered in places such as Texas, America to confirm that claim. This confirmation is discovered after experimental assertion that the mud-stone coating formed in low water environment is replaced by big rocks at the boundary. It is estimated that the asteroid impact caused a Tsunami which formed such deposition of boulders. These remains were discovered at dissimilar locations around the world and were made up of different thickness. The assortment of such information from different sites made the researchers conclude that about sixty-six million years ago, a big asteroid shower led to the disappearance of one of the major species on the world.

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