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While looking for out-of-date ideas on the origin of the first tetrapods I came across a very strange restoration of Dimetrodon (illustration to the left).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.

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A mount of Dimetrodon at the AMNH. From the Bulletin of the AMNH.The predatory pelycosaur Dimetrodon has always been a favorite of mine. Though not a dinosaur it has an appearance as bizarre as any dinosaur you care to name, and the function of the huge sail on its back is remains an enigma. What…
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Over the course of evolutionary history there have been a number of animals that have sported elongated neural spines, the structures sometimes aiding in the support of a hump (as in bison) and other times as the framework for a great sail (as in Spinosaurus). Of the group of "sail-backed" and "…
Today's photo is of the famous sail-backed pelycosaur Edaphosaurus from the Permian red beds of Texas. As if its sail wasn't enough to puzzle paleontologists, the fact that the neural spines bear "cross bars" further adds to the mystery (I know of no other animal that has exhibited such a feature…

I've always had a soft spot for Dimetrodon. As a child - perhaps I was five - my father brought me home a picture book of dinosaurs. He told me how herds of Dimetrodon would plunge into the warm ancient seas and sail in great fleets before the breeze, from island to island after the bounty of tender shoots. I remember him scratching a picture of Dimetrodon in the frost on the window-pane. It was all completely untrue of course, but a wonderfully attractive fable for a little boy.

Carl; I have a similar affinity for Dimetrodon. When I was young I had a very ugly plastic one and I remember playing with it in a pan of motor oil at my grandfather's house. (The oil looked like primeval ooze to me, though this was no excuse when my parents found the toy in the oil later.)

And, oddly enough, what your father told you about them sailing is not far off from what E.D. Cope once proposed for another sail-backed synapsid called Edaphosaurus. If I remember correctly Cope even drew a sketch of what one might look like while sailing in a pond, but I have never been able to find that image.

Here's a link for those who, like me, don't have direct access to this on Google Books:
http://www.archive.org/stream/geologyphysicalh00clelrich#page/490/mode/…
It says "modified after Jaekel". I've actually seen such an illustration before, in Jaekel's book "Die Wirbeltiere". It's online here:
http://www.archive.org/stream/diewirbeltieree01jaekgoog#page/n157/mode/…
For some reason, the head of the animal is cut off in the scan. Jaekel writes on the following page that a sail would have been useless to the animal, and that the spines freely protruding from the back for defensive purposes would make much more sense.

By Lars Dietz (not verified) on 12 Oct 2009 #permalink

I'm another with a soft spot for Dimetrodons. My memory is of a set of cheap plastic prehistoric animals that included a Dimetrodon, an Ankylosaurus, a Saber Toothed Tiger, and Mammoth. And, yes, that was my first mammoth. The mix of extinct animals from different periods wasn't unusual for the time, but, now that I think about it, the inclusion of the Ankylosaurus and Dimetrodon, instead of some of the more popular dinosaurs, was a bit odd.

I love how it can't seem to support its own weight.

It looks like it's passed out from a drunken binge.

If that illustration wasn't used in 'Alice in Wonderland' it should have been.

From a punk rock paleontologist in training, words can't describe just how much I love that drawing. Going to have to save it!

By Tor Bertin (not verified) on 12 Oct 2009 #permalink

Jaekel writes on the following page that a sail would have been useless to the animal, and that the spines freely protruding from the back for defensive purposes would make much more sense.

Defense against what, one wonders. Ol' Dimetrodon was among the very largest terrestrial animals of its day.

I love the image anyway. One should make a t-shirt of it.

By Andreas Johansson (not verified) on 12 Oct 2009 #permalink

This proves beyond a doubt that the Mohawk is the oldest hair style....

We once had an introductory biology test with a picture of Dimetrodon identified as a dinosaur. I think all introductory texts should havea few glaring errors so the instructor can point them out and fight the if it is in a textbook it must be true idea.

By Jim Thomerson (not verified) on 13 Oct 2009 #permalink

Strange image indeed! As a child, I played with plastic dinosaurs, Dimetrodon among them (yes I know it's not a dinosaur, but someone neglected to tell toy makers that!) A few years ago, I did happen to see an arist's new take on Dimetrodon, and it wasn't the squat, sailed creature we're all used to, but a sleak animal walking upright, in the manner of a crocodile's "high walk". Now if I can only remember when and who! Dimetrodon is so fascinating in part because of that flamboyant sail,which no creature in the modern world has, truly "prehistoric" in aspect.

By Raymond Minton (not verified) on 13 Oct 2009 #permalink

This new book, which I'm absolutely loving, has an incredible Dimetrodon digital painting in it. It's on pages 188-189 and is almost worth the price of the book.