Dimetrodon is one of the most recognizable and fascinating prehistoric animals, and a favorite of many dinosaur fans who learned early on that despite its frequent inclusion in dinosaur books and toy playsets, Dimetrodon was NOT a dinosaur!
Dimetrodon lived during the Permian period around 295-275 million years ago, a time period about 50-60 million years before the first dinosaurs. Most of their remains come from the red rock fossil beds of central Texas and Oklahoma, although they have been found as far away as Germany. What??? Germany? Yes–during the time when Dimetrodon lived, Germany was part of a supercontinental land mass known as Pangea that connected the continents of North America and Eurasia.
Dimetrodon was a primitive pelycosaur, an animal that in many ways retained reptile features but was not, in fact, a reptile. The most recent studies of Dimetrodon place this creature in a unique evolutionary category, one that has diverged from its reptilian ancestors and moved on a path toward becoming a mammal. With that said, Dimetrodon is clearly not a mammal. It was undoubtedly cold-blooded, for one thing. Mammalian traits such as fur, three middle ear bones, and the practice of young feeding on milk from a nursing mother were still many millions of years away. But Dimetrodon did have some critical traits that separate it from reptiles: it had one hole in the skull behind the eye socket which made it an early synapsid, a category of animals that includes all mammals today. Reptiles, including dinosaurs, typically have two such holes. Dimetrodon also had different types of teeth in its mouth, including large canines. The name Dimetrodon, given by famed paleontologist Edward Drinker Cope in 1877, means “two types of teeth,” and evidence suggests it engaged in the process of chewing food rather than just swallowing chunks whole (like many reptiles, including alligators and snakes, do today).
There are plenty of debates still going about Dimetrodon’s features. It has been argued for decades that the large sail on its back performed a heat-regulatory function that allowed the animal to warm up faster than an animal its size might without it. That has been argued though, and some paleontologists today believe that heat regulation was probably not an important aspect of the sail. Many believe that it performed the primary function of most animal sails, crests, and horns throughout history: attracting a mate.
While it is not directly on the evolutionary path of modern humans, there is little doubt that Dimetrodon is more closely related to modern mammals than are birds, reptiles, fish, or amphibians today. So where can one go to see some great Dimetrodon fossils? Fortunately many exist, and there are quite a few museums that display full fossil mounts. Here are some of the best in North America:
Allosaurus Roar’s Top Dimetrodon Displays
(15) Utah State University Eastern Prehistoric Museum, Price, UT
I love seeing a Dimetrodon at any museum; it’s certainly one of my favorite prehistoric creatures, and any museum that displays it is better for having done so, at least in my book. With that said, the display at the USU Eastern Prehistoric Museum is good but not great. The skull is great, and I love the pose, but somehow it looks off to me with the rest of the body at an odd angle. I don’t love the fact that the large spines on the back are held together with a sail-shaped matrix; I prefer to see the spines separated and then I can guess what the sail might have looked like on my own. Also, when I visited, this display had outdated scientific information that still referred to Dimetrodon as a reptile.
(14) Natural History Museum of Utah, Salt Lake City, UT
The Dimetrodon at the Natural History Museum of Utah has a large and impressive skull, and I like the open-mouth look in the display. I’m less of a fan of the “half” display, where one side of the animal’s rib cage and legs are not shown. Still, it’s an attractive specimen in a great museum.
(13) New Mexico Museum of Natural History, Albuquerque, NM
One of the real challenges in creating a life-like fossil mount using only one side of the animal is that when the skull is complete, it therefore sticks out at an odd angle compared to the rest of the body. The beautiful Dimetrodon at the New Mexico Museum of Natural History is slightly more realistic looking than some that present the animal in the “half display” format, but the sail-shaped matrix holding the spines together also limits this great fossil from a higher place on this list.
(12) Wyoming Dinosaur Center, Thermopolis, WY
At the Wyoming Dinosaur Center, the Dimetrodon on display is not terribly large but quite good. Still, it has some oddities that I am not a fan of. For one, the unnatural dark color of the holes in the skull and some of the teeth help visitors identify the areas that are so important and interesting about Dimetrodon, but look a little funny when seeing the fossil. As noted, I am also not a fan of the spines being held together by the “sail,” although it is common in museum displays.
(11) Brigham Young University Museum of Paleontology, Provo, UT
This relatively small specimen at B.Y.U. is displayed with all four legs, but the ribs and sail are held together by some type of matrix material. I wish the jaws were open more and the pose more dynamic, but this is a really good fossil and is displayed next to the herbivorous but similarly-shaped synapsid Edaphosaurus.
(10) American Museum of Natural History, New York, NY
I have to admit I’m always a little disappointed in the Dimetrodon mount at the incredible American Museum of Natural History. So many of the best prehistoric specimens are on display at this museum that it is surprising when a fossil lets you down, particularly when many of Cope’s early Dimetrodon fossils ended up in the collections at the American Museum. While the display specimen is great, I’m not a fan of the completely closed mouth and the one-sided display. Still, it is large and impressive otherwise, and it is mounted next to a well-known painting of Dimetrodon by legendary paleoartist Charles R. Knight.
(9) Museum of Ancient Life, Lehi, UT
The large Permian period display at the Museum of Ancient Life has several terrific fossils, and for me the highlight is the Dimetrodon. It is shown menacing three Eryops in front of a large mural depicting its Permian environment.
(8) Cleveland Museum of Natural History, Cleveland, OH
I really like the Dimetrodon on display at the Cleveland Museum of Natural History. It’s an attractive mount: the sail is large but not uniformly round like one often sees in museum mounts where the spines are held together in a sail shape. It is also displayed near other Permian period fossils, and there is a great deal of educational information available.
(7) Denver Museum of Nature and Science, Denver, CO
The famous red rock formations that have delivered the majority of Dimetrodon specimens are beautiful, and when you visit them, they often stand out from the various browns and greens of the rocks above and below them. Seeing the dramatic display of the red-tinted Dimetrodon and Eryops “fighting” in Denver is a reminder of the fossilization process whereby fossils take on the color of the minerals that seep into the bones and harden over millions of years.
(6) University of Michigan Museum of Natural History, Ann Arbor, MI
The Dimetrodon on display at the University of Michigan is undoubtedly my favorite, for very personal reasons. As an undergraduate, I would often look through the museum displays before and after my work-study job in the same building. A family tragedy occurred during my freshman year, and shortly after I returned to school, I once found myself in a daze just staring at this Dimetrodon for what seemed like an hour. Those were rough days for me personally, and I’ll never forget sitting there in the museum looking at the bones of an animal 290 million years old and having a conversation with it in my mind. Fossil therapy for me, I suppose. This beautiful specimen was brought to the museum by one of the first Dimetrodon experts, famed paleontologist E.C. Case, who worked at the University. Beside the mount there is a skull (shown above) and a lot descriptive information about this amazing animal.
(5) Royal Tyrrell Museum, Drumheller, AB
The Dimetrodon display at the Royal Tyrrell Museum is terrific…it actually features two mounts in front of a beautiful mural depicting a Permian scene. Nearby are other fossils from the same environment, including the Dimetrodon‘s erstwhile museum foe, Eryops. This is the only Dimetrodon display I’ve seen that features a full skeletal mount of more than one such animal.
(4) Sam Noble Oklahoma Museum of Natural History, Norman, OK
Many Permian period fossils have been unearthed within 50 miles of the University of Oklahoma, and the Sam Noble Museum has a wonderful Dimetrodon on display. Not only is the specimen large, it is posed well and shown near other Permian animals such as Edaphosaurus, Eryops, and Diplocaulus. I love the tall and sometimes crooked spines, I believe it gives the mounted specimen more character and seems more realistic than the many mounts that look absolutely straight and in perfect symmetry.
(3) Field Museum of Natural History, Chicago, IL
The Dimetrodon at the Field Museum is fantastic. The skull is large and interesting; the spines look very natural and the legs strong and powerful. Some of Cope’s early discoveries ended up in Chicago in the collections here, and this mount is one of my favorites. It is also displayed near other Permian animals, including the closely related Sphenacodon, which was very similar to Dimetrodon, but lacked the large neural spines.
(2) Houston Museum of Natural Science, Houston, TX
“Willi” the Dimetrodon was uncovered in Texas during Houston Museum of Natural Science (HMNS) digs in the late 2000’s. This specimen is gorgeous, his “red bed” origin is clear in the coloration of the fossils. Some of his spines are bent a little, and researchers believe they were not bent in the fossilization process but rather during his lifetime. This full fossil mount is displayed in the fantastic Morian Hall of Paleontology at HMNS.
(1) Smithsonian National Museum of Natural History, Washington, DC
I absolutely love the Dimetrodon on display at the Smithsonian. The specimen is large with a beautiful skull, and is posed in a very active display. It’s a great fossil, and a great fossil mount. In the newly renovated (2019) Hall of Fossils it sits atop a nice perch and the new lighting really helps this beauty stand out.
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