Rattlesnake

## Evolutionary Timeline of the Rattlesnake Rattlesnakes (genus *Crotalus*) are venomous pit vipers native to the Americas, evolving from ancient snake lineages. Their evolution was shaped by environmental pressures such as aridification, prey specialization, and predator avoidance in North and South American landscapes. Key adaptations include heat-sensing pits, venom delivery, and the iconic rattle for warning. ### Key Milestones: - **Cretaceous Period (100-66 MYA)**: Ancestral snakes diverge from lizards, developing limbless bodies for burrowing and hunting in forested environments. - **Eocene Epoch (56-33 MYA)**: Early viper-like snakes emerge in Asia and Europe, with basic venom systems evolving under pressures from mammalian prey proliferation. - **Miocene Epoch (23-5 MYA)**: Viperidae family diversifies in North America; rattlesnake ancestors develop heat-sensing pits amid grassland expansion and cooling climates. - **Pliocene-Pleistocene (5 MYA-Present)**: Rattlesnakes evolve the rattle structure from modified tail scales, adapting to arid deserts and avoiding large predators through warning signals. These transitions highlight how climate shifts and ecological niches drove rattlesnake specialization.