8.9B The Fossil Record Level 6 – 03
The Cambrian period is an important period in the evolution of life on Earth. It seems to be the time when major groups of animals first appeared. Many major phyla that make up the modern animal phyla seemed to have appeared at this time. Scientists have been puzzled by this “Cambrian Explosion.” During this time, the diversity of life seemed to have increased very quickly.
As scientists use new technology, some of the ideas about fossils have changed. We now know a body can change due to changes in the environment. This has led to different reasons for the Cambrian explosion. New studies show that organisms slowly became more complex. During the Cambrian era, the first fossils of species with exoskeleton were found.

Scientists think the reason for many different groups of fossils during this period is due to the evolution of hard body parts. As species adapted to the environment, they developed an exoskeleton. These preserve better than soft tissue. Organisms in the pre-Cambrian era had soft tissues. So, there are more fossil from the Cambrian era than of any earlier time.
Fossils of pre-Cambrian chordates have been found in Australia. These fossils provide a link between them and the phylum that humans belong to. As we know more, it seems that modern organisms have slowly evolved over a large geological time.
Scientists have found well preserved soft tissues of animals. These fossils were found using Xray imaging. They were fossils of an early ancestor that lived during the Cambrian period. These fossils help scientists to understand the history of life. They also support the theory of gradualism.
Jeremy learned that flowering plants have also changed over time. The origin of flowering plants has confused scientists. Flowering plants have suddenly appeared in fossil record recently. A new study shows that flowering plants did exist more than 100 million years ago. This study was based on fossil record only. The older fossils have not been found because flowering plants were rare. Also, the chance of fossils forming is very low. We know that ferns and gymnosperms were the main species in the early ecosystem. They likely overshadowed flowering plants. But slowly flowering plants became the most common and diverse group on earth.
Jeremy was excited to see the fossils that day. He knew that more studies were needed in the field. He would like to become a paleontologist. Perhap, one day he can do research and find out more about the story of evolution. The thought put a big smile on his face as he walked home.