Alligator

## Evolutionary History of Alligators Alligators belong to the family Alligatoridae within the order Crocodilia, which originated from archosaur reptiles during the Late Triassic period around 250 million years ago. Their evolution involved adaptations to aquatic lifestyles, survival through mass extinctions, and responses to changing climates. Key environmental pressures included global cooling, sea level changes, and competition with other predators, driving traits like powerful jaws and armored bodies. ### Key Milestones - **Late Triassic ( ~250 MYA)**: Emergence of early crocodylomorphs, ancestors to all crocodilians, adapting to semi-aquatic environments amid warm, humid conditions. - **Cretaceous ( ~100-66 MYA)**: Divergence of Alligatoridae from other crocodilians; large forms like Deinosuchus evolved as apex predators in river systems, facing pressures from dinosaurs and climate shifts. - **K-Pg Extinction (66 MYA)**: Survival of alligator lineages through the mass extinction event, likely due to burrowing and estuarine habitats that buffered against environmental catastrophe. - **Eocene-Oligocene ( ~56-23 MYA)**: Radiation of modern alligator relatives in warmer climates; cooling trends selected for species with better thermoregulation. - **Miocene-Present ( ~23 MYA-Now)**: Split into genera like Alligator, with the American alligator (Alligator mississippiensis) and Chinese alligator (Alligator sinensis) adapting to temperate and subtropical regions amid ice ages and human impacts.