During which geological period did dinosaurs first appear?

Dinosaurs first appeared during the Triassic Period, which spanned from approximately 252 to 201 million years ago. This period marks a significant point in the history of life on Earth as it followed the mass extinction event at the end of the Permian Period, allowing for the diversification of reptiles. The early dinosaurs were small and not yet the dominant terrestrial vertebrates; that shift occurred later in the Jurassic and Cretaceous periods.

The Triassic is characterized by the emergence of many new species, including the first true dinosaurs. As these reptiles evolved and diversified, they began to occupy various ecological niches, leading to the dominance of dinosaurs in the Mesozoic Era. Understanding the context of the Triassic Period's significance is essential in studying the history and evolution of these iconic organisms.