Therapsids are a group of synapsid reptiles that lived during the late Paleozoic and throughout the Mesozoic eras. They are considered ancestors of modern mammals and are characterized by features such as differentiated teeth and a more advanced jaw structure. Therapsids played a crucial role in the evolution of mammals, showcasing adaptations that allowed them to thrive in various environments. These creatures first appeared around 275 million years ago and included diverse forms, such as the gorgonopsids and dicynodonts. Over time, therapsids evolved into mammals, marking a significant transition in vertebrate evolution. Their fossil remains provide valuable insights into the development of mammalian traits.