Weird Backs Month #05 – Edaphosaurus
The namesake of the edaphosaur family, and the largest, Edaphosaurus lived during the Late Carboniferous and Early Permian (~300-280 mya) of the USA, with possible fragmentary fossils also known from Central Europe. It was one of the earliest large herbivorous tetrapods – some species reaching up to 3.5m in length (11′5″) – with dense “pavements” of vegetation-grinding teeth on the roof of its mouth and lower jaws.
Its huge sail featured numerous crossbars, giving the bones a particularly bristly appearance. Whether they supported any additional soft tissue is unknown, although the trend among Edaphosaurus species over time was to have fewer but more elaborate bars.
Oddly, the neural spines at the very back of the sail are usually preserved strongly bent, curving over and often forcing their way down to impact onto the vertebrae behind them. This is likely a result of a lifetime of normal movement – Edaphosaurus probably walked rather like a lizard, flexing its body from side to side, and such motion would have put considerable inertial stress on the thinner and less well-supported rear spines, deforming them as they grew.
Edaphosaurus, the other sail-backed synapsid.
