First Therapsids — Descendants of the Pelycosaurs
Even before the last of the pelycosaurs died out, their successors, the therapsids, lived among them. These earliest therapsids most likely arose from among those pelycosaurs called
sphenacodonts. They were in good company. Dimetrodon, the famous fin-backed pelycosaur, sprang from this same group of aggressive predators.
Those first therapsids must have evolved away from the warm wet lowlands. So ... which habitat shaped them ? They were obviously adapted to a marginal habitat — probably
the cooler, drier upland environment. Here, those early therapsids would have faced fewer competitors for their main food source — crunchy