They were the earliest known herbivorous amniotes and, along with the Diadectidae, the earliest known herbivorous tetrapods.[3] The head is small in relation to the bulky body, and there is a tall sail along the back, which may have functioned as a thermoregulatory device.
Classification
The interrelationships of Edaphosauridae was investigated in details by David M. Mazierski and Robert R. Reisz (2010). The cladogram below is modified after their phylogenetic analysis.[4]
^David M. Mazierski and Robert R. Reisz (2010). "Description of a new specimen of Ianthasaurus hardestiorum (Eupelycosauria: Edaphosauridae) and a re-evaluation of edaphosaurid phylogeny". Journal of Vertebrate Paleontology. 47 (6): 901–912. Bibcode:2010CaJES..47..901M. doi:10.1139/E10-017.
^Benson, R.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Palaeontology. 10 (4): 601–624. doi:10.1080/14772019.2011.631042. S2CID84706899.
Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, WH Freeman & Co.
Reisz, R. R., 1986, Handbuch der Paläoherpetologie – Encyclopedia of Paleoherpetology, Part 17A Pelycosauria Verlag Dr. Friedrich Pfeil, ISBN3-89937-032-5