Horse

The evolutionary history of horses spans over 50 million years, beginning in the Eocene epoch with small, forest-dwelling ancestors and leading to the modern Equus genus. Key transitions were driven by environmental changes, such as the shift from dense forests to open grasslands, which favored larger body sizes, longer legs for speed, and adaptations for grazing. Important pressures included climate change, predation, and the expansion of savannas. ### Key Milestones: - **Eocene (55-45 million years ago)**: Emergence of Hyracotherium (Eohippus), a small, dog-sized browser with multiple toes, adapted to forested environments. - **Oligocene-Miocene (34-5 million years ago)**: Evolution of Mesohippus and Merychippus, with increased size, three-toed feet, and teeth suited for grazing as forests gave way to grasslands. - **Pliocene (5-2.5 million years ago)**: Appearance of Pliohippus, the first single-toed horse, enhancing speed on open plains to evade predators. - **Pleistocene (2.5 million-10,000 years ago)**: Rise of Equus, the modern horse genus, with further refinements for endurance and grazing in diverse habitats. - **Holocene (10,000 years ago to present)**: Domestication by humans around 6,000 years ago, leading to diverse breeds shaped by selective breeding.