Atlantic Salmon

# Evolutionary Timeline of Atlantic Salmon The Atlantic Salmon (*Salmo salar*) belongs to the Salmonidae family, with roots tracing back to ancient fish lineages. Their evolution involved adaptations to changing environments, particularly the development of anadromous life cycles (migrating between freshwater and saltwater). Key pressures included glacial cycles, ocean temperature shifts, and predation. ### Key Milestones: - **Devonian Period (419–358 million years ago)**: Emergence of early jawed fishes, ancestors to all bony fishes including salmonids. - **Cretaceous Period (145–66 million years ago)**: Diversification of teleost fishes; early salmonid-like species appear in freshwater habitats. - **Eocene Epoch (56–33 million years ago)**: Salmonidae family evolves, with ancestors adapting to cold, oxygen-rich waters. - **Pleistocene Epoch (2.6 million–11,700 years ago)**: Glacial cycles drive anadromous adaptations, enabling migration for spawning in response to changing sea levels and habitats. - **Holocene Epoch (11,700 years ago–present)**: Modern Atlantic Salmon refine migratory behaviors, influenced by human activities and climate change.