What era and period did reptiles first appear?
they evolved in marsh habitats around 350 million yrs ago
The first known decedent for the dinosaurs was the hylonomas.
The Mesozoic Era in the Triassic Period. Dinosaurs first appeared during the Triassic Period (250-230 million years ago) and were on the Earth through the Jurassic Period (200-145 million years ago) until the end of the Cretaceous Period (65 million years ago). This whole era is called the Mezozoic Era (250-65 million years ago). Dinosaurs are classified as a diverse range of reptiles, but the first true dinosaur evolved from Archosaurs (Ruling Lizards).