Biological Evolution: The Fossil Record Essay

Submitted By nk2171
Words: 1004
Pages: 5

Opening Statement
Good morning, everyone. My name is Andrew and here in my team are Raphi and Bec. Raphi will be answering the proposed questions and Bec will be rebutting for our team. For today’s debate, my team believes that the Fossil Record is the best evidence to support the theory of biological evolution.
When we speak of biological evolution, we are referring to the adaptation of inheritable traits within a population across many generations. In 1859, Darwin put forth his theory of evolution, which described the methods in which species varied over generations. Biological evolution occurs when a population’s gene pool changes by processes such as mutation, natural selection or genetic drift. Genetic mutations occur when there is a mistake when copying a DNA code in cellular division and, therefore, change an individual’s genes. Natural selection is when individuals who have more beneficial traits have a better chance of survival, and therefore, reproduction and passing down the beneficial traits to their offspring. Genetic drift is the change in the frequency of a gene variant in a population due to random sampling, causing the unpopular genes to be outnumbered. By examining numerous fossils, one can observe the transition from an organism of the past to one of the present.
Fossils are any remains or traces of biological organisms of a former geologic age such as skeletons, footprints, etc. Unlike the other forms of evolutionary evidence, fossils are the only visual glimpse we have of the past. Scientists can determine a creature’s skin, eating habits and physiology just from looking at their skeletons. Without the help of fossils, it would be almost impossible to visualise extinct species. From several skeletal fossils, we can observe how a horse has evolved from its ancestors, the dawn horses. We learn that the modern horse has evolved from the dawn horse by these transitional forms which link the horses to each other by how they closely resemble each other. Throughout 50 million years, the dawn horse’s legs have elongated in order to adapt to more efficient galloping. Their bodies have slowly been built up to be much more muscular in order to compete for survival against possible predators. This evolutionary chain provides enough evidence that these horses have adapted over time.
Also, with the help of radioisotope technology, we can determine approximately when a fossil was alive. This can show us how long it took to get from one evolutionary stage to another and how many generations it takes to make significant adaptations across a population’s gene pool. One example of a dramatic evolutionary adaptation is the Iguanodon.
In the 19th century, Mary Ann Mantell discovered a tooth, which was thought to be of a large iguana. However, after assembling its full skeleton, it was recognised as the tooth of an Iguanodon, which is a dinosaur from the Jurassic Period, over 150 million years ago. This dinosaur is one of the iguana’s ancestors since it’s skeletal structure, although a lot bigger than an Iguana, has many traits which make it resemble one, especially its teeth.
Organisms have no doubt changed significantly over time. In rocks more than 1 billion years old, fossils of single-celled organisms are found. In rocks that are about 550 million years old, fossils of multi cellular animals can be found. At 500 million years ago, ancient fish without jawbones surface and then at 400 million years ago, fish with jaws are found.
And now, gradually, new animals appear: amphibians at 350 million years ago, reptiles at 300 million years ago, mammals at 230 million years ago, and birds at 150 million years ago. As the rocks become more and more recent, the fossils look increasingly like the animals we observe today, which is evident that fossils are a sure fire way to determine evolution.
In conclusion, my team and I strongly believe that the fossil record is the best evidence to support biological evolution on