Changes in animals over time can be seen through the study of fossils. Fossils are the remains of ancient organisms, and they can provide invaluable insight into the history of animal evolution. An analysis of the changes seen in fossils over time can reveal the causes and effects of the evolutionary process. Environmental changes, such as climate shifts or changes in food sources, can trigger evolutionary adaptations, allowing animals to survive and thrive in a new environment. These evolutionary changes have allowed animals to develop specialized physical characteristics and behaviors that can help them better adapt to their environment.