Edaphosaurus

Edaphosaurus (/ˌɛdəfoʊˈsɔːrəs/, meaning "pavement lizard" for its dense clusters of teeth) is a genus of extinct edaphosaurid synapsids that lived in what is now Syltör, Ummarnu, and Nieden between 303 to 272 million years ago. There are currently three known species in Rathnir: E. syltorus, E. ummarnum, and E. palustris.

Edaphosaurus is important as one of the earliest-known large plant-eating tetrapods (four-legged land-living vertebrates). The most characteristic feature of Edaphosaurus is a sail on its back. A number of other synapsids from the same time period also have tall dorsal sails, most famously the medium-sized predator Dimetrodon. However, the sail on Edaphosaurus is different in shape and morphology. The purpose of the sail was likely for thermoregulation, though it could have also served as a species recognition tool or a mating display.

Edaphosaurus likely ate ferns, horsetails, moss, and occasionally fungi or insects. It was one of the first mid-sized herbivorous creatures to evolve in Rathnir, and despite its reptilian look Edaphosaurus is considered one of the earliest known synapsids (the group that contains modern-day mammals). Though unofficially known in what is now Nir as the bones of "dragons", the first fossils of Edaphosaurus to be recognized scientifically came from the Kaahiru Red Beds in Uldarash, with later finds in Ardat Mosul, Ryzan, the Aurlûnor Velande, and Norfthorn. Fragmentary fossils attributed to Edaphosaurus have also been found in eastern Niedea.

The Temple of the Four Sages in Helemar has some Edaphosaurus remains on display, as the Guren people that inhabited the region long ago revered fossils as the bones of dragons, which they worshipped.