A progenitor species refers to an ancestral species from which other species have evolved. This concept is crucial in the study of evolution, as it helps scientists understand the relationships between different organisms. By examining the traits and genetic material of progenitor species, researchers can trace the lineage and adaptations that led to the diversity of life we see today. In the context of evolutionary biology, a progenitor species can be identified through fossil records and genetic analysis. For example, the common ancestor of all mammals is considered a progenitor species, from which various groups like primates, carnivores, and rodents have diverged over millions of years.