👉 Echinodonts are a group of extinct marine reptiles that lived during the Mesozoic Era, about 65 million years ago. They were characterized by a flattened skull and an elongated body shape, often with large teeth and scales on their back. Echinoderms evolved from the early stages of invertebrates, which included some of the earliest known creatures, such as bryophytes (plants) and mushrooms.
