 What is evolution and where is the supporting evidence for it? The theory of evolution states that individuals within a species show a wide degree of variation and those individuals with characteristics best suited to their environment are more likely to survive and reproduce. This theory grew from studying the variations and similarities in living animals and plants, but also very importantly by studying fossils. The study of the number and placement of fossils within certain types and areas of rock is known as the fossil record. This record gives us an indication of the types of animals and plants that existed in the past for many millions of years ago, right up until around 10,000 years ago. Fossils of single-celled organisms such as cyanobacteria from Australia have been found in rocks that are more than 3.5 billion years old. Paleontologists are people who study fossils. By comparing fossilized body structure and fossilized tracks of movement, they painstakingly piece together the story of how animals and plants have changed and evolved over time. Importantly, by comparing fossils from different species, paleontologists can look for similarities in structure to try and work out which species are related to which others. This work has enabled scientists to visualize how some species have evolved from others. The discovery of transitional fossils has greatly assisted paleontologists understanding of how their evolutionary process occurred. For example, in 1988, scientists found a 370 million year old fossilized fish with a hand like fin, suggesting a transition from sea-dwelling creature to land. Look at this picture of fish fingers. Meanwhile, the discovery of transitional reptile fossils with mammal-like jawbones has enabled paleontologists to date the emergence of early mammals to about 245 million years ago. Mammals did therefore live alongside the dinosaurs. The fossil record has enabled scientists to track the path of human evolution from great apes and has even allowed us to identify where humans and chimpanzees went their separate ways. Our last common ancestor lived about 5 to 7 million years ago. Since that time, over 20 hominid species have been discovered. Tracing the lineage of plant and animal species using fossil record is not an exact science. The lack of transitional fossils makes this all the harder, leading to significant gaps in the fossil record. Because the formation of fossils is a rare event, many transitional species have just not formed fossils. However, as new fossils are being discovered all the time, we can expect at least some of these gaps to eventually be filled. In this video, you have learnt what the fossil record is and how it has contributed to our understanding of evolution. You have also learnt about problems with the fossil record. Can you find any other examples online or in books of transitional fossils?