One Creepy Dimetrodon

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I love flipping through old paleontology textbooks. Many times the text and images inside them have been reproduced from other sources or bear a close resemblance to similar titles published at about the same time, but every now and then I find something really unusual. Such was the case while I was skimming through H.F. Cleland’s 1916 Geology: Physical and Historical.

While looking for out-of-date ideas on the origin of the first tetrapods I came across a very strange restoration of Dimetrodon (illustration to the left). Dimetrodon was a spenacodontid synapsid, an odd creature that, despite its looks, was more closely related to you and me than to reptiles. Perhaps its most prominent characteristic was the sail that was suspended between the bony struts on its back, but the restoration in Cleland’s book lacked such a sail. It looked like a pissed off, punk rock Dimetrodon.

Perhaps I was so struck by this illustration because portrayals of Dimetrodon have changed little, if at all, during my lifetime. It has always been a squat, sail-backed monster since the time I first saw its skeleton in the old Jurassic Dinosaur Hall at the American Museum of Natural History. Restorations of dinosaurs underwent a major overhaul when I was young, but Dimetrodon has always been the same. Closer to the time of its discovery, though, it appears that there were different ideas about the shape of its sail, the length of its tail, and its posture. Just why paleontologists like E.C. Case created these different restorations, though, I have yet to fully discover.