Name Meaning: Pavement Lizard
Geologic Era: Late Carboniferous to Early Permian
Location Discovered: Texas (Red Beds)
Size: 0.5 meters to 3.5 meters long
Estimated Range: Southern North America, possibly also Czech Republic and Germany
Extinction Date: 280 million years ago
This is part of a neural spine from Edaphosaurus. They are structurally similar to those found in Dimetrodon, a similar looking, predatory synapsid. The biggest difference is that Edaphosaurus spines possess crossbars, where Dimetrodon spines do not. This is just a small portion of one of the neural spines; a complete spine could exceed a half meter in height.
Edaphosaurus earned its name from the pavement like appearance of the interior of its mouth. Its teeth indicate that it was an herbivore, as does its general body structure. As shown by its body structure, Edaphosaurus would have been build wide and low to the ground. This setup would allow for the housing of a sizable gut cavity. This would have enabled Edaphosaurus to ferment large quantities of food in its hindgut, as wear patterns on Edaphosaurus teeth show that it did not process food extensively with its mouth.
In that sense, Edaphosaurus could be seen as a Permian era cow or sheep, constantly grazing and using a similar digestive process to modern ruminants. Edaphosaurus also had a very small head for its body size, which means it would probably have to constantly take in food to satisfy its larger body.
Like Dimetrodon, the function of the sail of Edaphosaurus is up for debate. It possibly had a thermoregulatory function, though mechanical analysis of the sail show that it would not have been terribly efficient for this purpose. An alternate idea is that the sail served as a display feature, either to attract mates or to deter a predator. A large sail could project to a potential mate the overall health of the animal, with a bigger, flashier sail meaning a “better” animal. It is not known how the sail of Edaphosaurus was colored, but if it served as a sexual display feature, it is not unreasonable to assume that it would have been brightly colored.
In terms of deterring a predator, any feature that makes an animal look larger and more dangerous that it really is would be a positive thing. Predators will generally try to minimize danger to themselves, so a fierce looking prey item would be a less appealing target than a smaller, softer one. Though the spines of Edaphosaurus were rather thin and not terribly resilient, just making the animal look larger could possibly be enough.
Full Skeleton: By Daderot – Daderot, CC0, https://commons.wikimedia.org/w/index.php?curid=19814010
Life Reconstruction: http://spinops.blogspot.com/2016/04/edaphosaurus-pogonias.html