This field sketch of a Captorhinus shows it much closer to a Dimetrodon that it would have wanted to be, in order to illustrate its small size. (c) Robert T. Bakker
In addition to being teensy, the Captorhinus was also extremely primitive. As Dr. Bakker describes it, "If you started as a Captorhinus, you could end up evolving into just about anything." This species is close to the base of almost every modern species' family tree.
If you saw one today, it would look like a chunky lizard with a pointy snout. It also had two complete rows of teeth, for cracking and eating something small and hard, like snails or millipedes.
The HMNS team have found dozens of Captorhinus fossils at the site, including vertebrae, ribs, legs and several examples that are almost complete skeletons. Shed Dimetrodon teeth have been found with these fossils, proving yet another species had a reason to run when the Texas Finback lumbered on the scene.