What is the term for an animal or plant fossil that serves as an intermediate between two groups?

The term "transitional fossil" refers to fossils that exhibit characteristics of two different groups, thereby providing evidence of evolutionary change over time. These fossils are important because they help illustrate how species adapt and evolve, often showcasing features that are intermediate between ancestral and descendant forms. For example, a transitional fossil may display traits of both reptiles and birds, highlighting the evolutionary link between these two groups.

Transitional fossils offer invaluable insights into the history of life on Earth, supporting the theory of evolution by demonstrating the gradual changes that can occur in species over successive generations. This concept is essential in understanding the complexity and diversity of life, as well as the process of natural selection.

In contrast, other terms such as "ambiguous fossil," "primitive fossil," and "extinct fossil" do not capture the specific essence of connecting two distinct groups through evolutionary traits. Ambiguous fossils refer to specimens whose classification is unclear, primitive fossils denote earlier forms of life that may not show the transitional features, and extinct fossils indicate species that no longer exist but do not imply a connection between different groups.