How the Scientific Knowledge on Cetacean Evolution has Changed Over the Last Years (Essay Sample)

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How the Scientific Knowledge on cetacean evolution has changed over the last years
The order Cetacea is made up of marine mammals such as whales, dolphins and porpoises. Over time, these mammals have shown changes in characteristics and behaviour. Such changes in characteristics have attracted research by scientists especially biologists. As years elapse, there have been changes in knowledge on cetacean evolution due to the changes in features that these creatures display.
In the past 55-60 years ago, cetaceans have shown a significant change in the brain size. Their brains and memory capacity have hyper-expanded beyond the initial levels at the time when they were first discovered and studied. In fact, the current cetaceans have a brain capacity that is second to that of the modern man (Marino 3). Brain evolution of the whales, especially, has been of more interest to the scientists that have been on the ground carrying out research. At the moment, the only difference that exists between the cetacean and other mammalian brains is the architecture of the neocortex.
There is evidence to show that whales are descendants of land mammals. It still remains a mystery how these creatures changed structurally to adapt to marine life. In the first place, whales have the tendency of taking up oxygen from the air. This implies that they have no fully developed marine structures to facilitate full-time breathing in water. However, as a result of evolution, their characteristics have changed over time and they survive in the water bodies. Other members of the order such as dolphins show almost the same characteristics and this is evidence enough to prove that these mammals are changing with time.
Taking the case of whales, there are facts that have been put down in support of the facts that they changed with time to develop features that are adapted to marine life. Fossils of an animal called Pakicetus have been found in Pakistan and directly linked to the whale. This was a land mammal with well-developed legs (Stenstrom 2). A similar feature between the whale and this animal is the structure of the middle ear and its position.
With time lived another mammal with more related features to those of the whale. This was known as Ambulocetus patans (Stenstrom 3). This means the ‘walking whale that swims.’ It is thought to have occupied the ecological niche that is today taken over by the modern crocodile. It was in a position to move to land and capture a large prey and get back into the water.
The first whales were then located in the South-East Asia and have been given the family Remingtonecetidae. They reveal an improved ear structure especially to allow hearing inside water. As time elapsed, these mammals evolved to give rise to the present day whales that occupy the large water bodies of the world.
Modern evolution in cetaceans...