Atlantic Cod

## Evolutionary Timeline of Atlantic Cod The Atlantic Cod (*Gadus morhua*) belongs to the order Gadiformes within the ray-finned fishes (Actinopterygii). Its evolutionary history traces back to early bony fishes, shaped by major environmental changes like ocean temperature shifts, glaciation periods, and predation pressures. Key adaptations include cold-water tolerance and efficient swimming for migration. ### Key Milestones: - **Silurian-Devonian Period (~420-360 MYA)**: Emergence of jawed fishes and early ray-finned ancestors, adapting to marine environments with improved predation and feeding mechanisms. - **Triassic Period (~250 MYA)**: Diversification of teleost fishes, the group including cod, with advancements in fin structure for better maneuverability amid changing ocean ecosystems. - **Eocene Epoch (~50 MYA)**: Origin of Gadiformes order, driven by cooling oceans and the need for deep-water foraging strategies. - **Miocene Epoch (~20 MYA)**: Appearance of the genus *Gadus*, influenced by Atlantic Ocean formation and ice age cycles promoting cold-adapted traits. - **Pleistocene Epoch (~2.5 MYA - 11,700 YA)**: Glacial cycles shaped modern cod populations, enhancing schooling behavior and migratory patterns to exploit seasonal food availability.