I have always been fascinated by the animals that lived during the Permian time period, from roughly 300 million years ago up to around 250 million years ago–a time after vertebrates began to dominate the land but before the first dinosaurs evolved in the early Triassic. Possibly the most iconic creature during this time period is the sail-backed carnivore Dimetrodon. Less well-known, but just as interesting is the sail-backed herbivore Edaphosaurus, named in 1882 by the famous bone-wars paleontologist Edward Drinker Cope. While Dimetrodon was the most fearsome carnivore in its environment, Edaphosaurus was clearly a herbivore–its mouth had tightly-packed peg-like teeth and a palate that was designed for crushing plants. Both Dimetrodon and Edaphosaurus lived during the early part of the Permian and were members of the pelycosaur family. The pelycosaurs were a group of animals that have been referred to as “mammal-like reptiles” because of their development of later mammalian features such as differentiated teeth, a temporal fenestra (a hole in the skull behind each eye), and a hardening of the palate.
Edaphosaurus was a contemporary of Dimetrodon, although it is unclear if there was a predator-prey relationship. The large sail that developed in both creatures is reflected in the large neural spines of their skeletons, and is the most obvious distinguishing characteristic of each. For many years it was thought that the sail was used primarily as a mechanism for trapping and retaining heat, which was a critical need for a cold-blooded reptile. While that possibility can’t be excluded completely yet, today it is thought that the main function of the sail was species identification and mating display.
Fortunately for fans of these great Permian creatures, there have been a significant number of fossils discovered and quite a few museums display one or both of these animals. Here are my favorite Edaphosaurus displays:
(12) Carnegie Museum of Natural History, Pittsburgh, PA
The display at the Carnegie Museum is typical of many older fossil displays: the animal looks “complete” embedded in a plaster wall, but it is really only the left half of the legs and feet. Also, the sail and tail vertebrae, and ribs, are similarly encased in some type of material that holds them in place. It’s a really nice fossil, I just prefer the skeleton to be free of the material as much as possible.
(11) Yale Peabody Museum, New Haven, CT
The cute, relatively small Edaphosaurus on display at the Yale Peabody Museum is also mostly encased in plaster, but at least the plaster blends well into the background of the display. It is almost a mirror image of the Carnegie skeleton: at Yale the right-side legs and feet of the animal are displayed.
(10) Harvard Museum of Natural History, Harvard University, Cambridge, MA
At Harvard, the Edaphosaurus is displayed similarly to that at Yale. The right side of the animal is profiled, again the left legs and feet are missing. While I absolutely hate the glass display cases at Harvard (they are among the worst for allowing decent photographs), the fossil inside this one is very nice, with a beautiful skull and open mouth to be able to see the teeth very clearly.
(9) Brigham Young University Museum of Paleontology, Provo, UT
Like the displays listed above, the Edaphosaurus at B.Y.U. is mostly embedded in plaster, and again only the right-side legs and feet are displayed. I like this fossil quite a bit though, it seems more lively than the others and the sail is posed in a more realistic design than the almost perfectly rounded sails on some other specimens.
(8) University of Michigan Museum of Natural History, Ann Arbor, MI
In the Michigan museum, we once again see the left side of the animal on display. On this specimen, it is easy to see the crossbar nubs on the spines, which vary significantly by the species of Edaphosaurus. Currently, there are five recognized species, all fairly similar. Among their differences are slightly varying sizes and the visibility of the crossbars on the neural spines of the sail. The U-M fossil is a very nice skeleton. The ribs appear more rounded than in some others, and the sail looks a little more natural as well.
(7) Texas Memorial Museum, Austin, TX
I enjoy the beautiful Edaphosaurus at the Texas Memorial Museum. It is relatively small although it has a very long tail. The sail is displayed in the classic half-circle that we see in many of the older museum displays, but it is one of the rare displays that shows the creature turning its head: just about every other Edaphosaurus is shown looking straight ahead. There is a slight red tint to the rock displayed behind the skeleton, a nod to the Texas red-beds where the majority of these animals’ fossils have been discovered.
(6) Smithsonian National Museum of Natural History, Washington, DC
The Edaphosaurus at the Smithsonian National Museum of Natural History is the first on this list to be free from a plaster coat around it. And it’s a great fossil. Up close one can see the crossbar nubs very clearly, and it really makes a difference to see all four feet and legs. It is also very clear that when removed from the plaster backing, the neural spines aren’t as neat and perfectly aligned as they are sometimes displayed in the various molds you see in the examples above.
(5) Beneski Museum of Natural History, Amherst College, Amherst, MA
I really like the Edaphosaurus on display at the Beneski Museum. Free of a plaster backing, the spines in the sail are very interesting to look at. Up close you can see the crossbar nubs very clearly and the spines themselves twist and turn in interesting ways. Most of the left legs and feet are missing, but they do a nice job constructing a metal cast to replicate them, and it works very well.
(4) Sam Noble Oklahoma Museum of Natural History, Norman, OK
The fossil on display at the Sam Noble is quite beautiful. The spines soar and although not identical they are arranged in a wonderful fan-shaped display, and the head is turned slightly to the right. One thing I like about this display is that the animal is shown in a faux natural environment, which is the only one I’ve seen like it.
(3) American Museum of Natural History, New York, NY
There are two species of Edaphosaurus on display at the AMNH. One skeleton is much more complete than the other, but both are quite interesting. The full skeleton on display (below) is a very attractive example of this animal, while the partial skeleton above allows a good close-up view of the spines with their crossbar nubs easily visible.
(2) The Field Museum, Chicago, IL
While scientists believe Edaphosaurus was probably quite slow, like Dimetrodon it had a powerful build. You can easily see this in how compact and strong the Edaphosaurus on display at the Field Museum. It is very interesting to see the varied widths of the vertebrae that make up the “sail” on the back. Toward the front of the animal the bones are quite wide, probably twice as wide as those in the back. The Field Museum fossil is really terrific, and displayed beautifully.
(1) Perot Museum of Nature and Science, Dallas, TX
It’s no surprise that my favorite Edaphosaurus on display would be found in Texas. It’s only fitting: the majority of fossils of this interesting animal have been found in the state’s famous Permian red beds. Although the animal in Chicago is just as beautiful, I really like the pose of the display in Dallas. The Edaphosaurus is standing more upright, head up, surveying the landscape with its feet pointing forward rather than in the more traditional reptile pose with feet splayed out to the side.
Allosaurus Roar 