American Robin

# Evolutionary Timeline of the American Robin The American Robin (*Turdus migratorius*) is a songbird in the thrush family (Turdidae), with its evolutionary history rooted in the broader avian lineage. Birds evolved from theropod dinosaurs, and the robin's ancestors adapted to changing environments over millions of years, including climate shifts and mass extinctions. Key pressures included the Cretaceous-Paleogene extinction, ice ages, and habitat fragmentation, which drove traits like migration and foraging versatility. ### Key Milestones - **~150-160 MYA (Late Jurassic)**: Origin of birds from theropod dinosaurs, such as Archaeopteryx-like ancestors, enabling flight and aerial niches. - **~66 MYA (Cretaceous-Paleogene Boundary)**: Mass extinction event wipes out non-avian dinosaurs, allowing avian diversification; early neornithines emerge. - **~50-30 MYA (Eocene-Oligocene)**: Rise of Passeriformes (songbirds); thrush-like ancestors adapt to forested environments amid cooling climates. - **~20-5 MYA (Miocene)**: Divergence of Turdidae family; ancestors of *Turdus* genus spread across continents, influenced by tectonic shifts and vegetation changes. - **~2.5 MYA - Present (Pleistocene-Holocene)**: American Robin speciates in North America; ice ages promote migratory behavior and adaptation to varied habitats like grasslands and urban areas.