Researching Evolution Even Further
Like all living things, dinosaurs evolved slowly and gradually. It is believed that dinosaurs evolved from the Archosaurs, meaning 'ruling lizard'. Archosaurs aren't that much different from dinosaurs. However, these ancient reptiles were much smaller than most dinosaurs, and had certain characteristics that set them apart from their more famous descendants. The process leading up to the first dinosaurs can be followed through fossils of the early Archosaurs. Comparing fossils, palaeontologists have discovered that Dinosaurs and Archosaurs had very similar bone structure. It is also believed that birds have descended from dinosaurs due to the similar characteristics in which they had in common with the Velociraptor, a bird like dinosaur. These features include: feathers, shape of feet, the wishbone and the bone structure. The one difference is that the Velocitators' teeth are sharp and razor like, compared to birds that only have beaks.
There are many different theories as to how the dinosaurs became extinct.
Two of the main theories are that a meteor smashed into the Earth, causing the extinction of dinosaurs. It is believed that a cloud of dust, created by the meteor, altered the weather all around the world, causing the environment of the dinosaurs to alter, therefore the dinosaurs, not being able to adapt with the extreme changes, became extinct. The theory of the meteor is the most accurate; as scientists have found evidence that a meteor did strike the Earth around the same time that the Dinosaurs became extinct.
Fossils are the remains or impression of a prehistoric organism preserved in petrified form or as a mould or cast in rock. There are many different types of fossils. These include: moulds, casts, imprints, transitional fossils and living fossils. Moulds, casts or imprints are called 'Trace Fossils'. 'Transitional Fossils' show the transitional stages between 'before' and 'after'. It's the fossilised remains of a life form that shows qualities common to both the ancestral group and its derived descendants. 'Living Fossils' are species that still exist, but have remained unchanged for a very long time. For example, the Coelacanth is a deep water fish that is found along the coastlines of the Indian Ocean and Indonesia. The Coelacanth is considered a living fossil due to its apparent lack of significant evolution over the past millions of years. Fossils are considered evidence for evolution because evolutionary change is evidently acknowledged in the fossil record. Fossils are well ordered within rock layers, the oldest ones being at the bottom and youngest being at the top. Advances in our understanding have led to technologies that can find out a more accurate time frame for fossils (this is called Absolute Dating). Fossils tell us several things. By observing them, we can see the structure of animals in early times and how they probably lived. In terms of Evolution, fossils tell us how animals evolved, but they can also help contradict it.
Jean- Baptiste de Lamarck
The giraffe on the right hand side is not using its neck to graze on leaves high in the trees, whereas the giraffe on the right is.
Over time, the exercise of reaching up to graze the leaves up on the trees has altered the giraffe on the right hand sides' neck and legs. No change has happened to the giraffe on the left, due to its disuse of its neck and legs.
Therefore, the offspring has inherited the acquired traits of its parent, whereas the giraffe on the left has not changed over time
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