Diplocaulus is known for the long protrusions on the sides of its skull, which cause the skull to be shaped similar to a boomerang. Judging from its weak limbs and relatively short tail, it is presumed to have swum with an up-and-down movement of its body, not unlike cetaceans today. The wide head could have helped the creature glide through the water. Also, it is thought to have had defensive purposes as any predator like Dimetrodon (even the large-headed Eryops) would have a hard time trying to swallow a creature with such a wide head. A close cousin of Diplocaulus is Diploceraspis.
- Unknown hammerhead salamanders are reported in cryptozoology from time to time. In 1992, a Japanese artist made a small diplocaulus model which he photographed in a pan on a lawn, as if captured. The photo looked quite realistic and was circulated in 2004 and 2005 on forums such as cryptozoology.com, where many thought it was a real salamander.
- In the final episode of Neon Genesis Evangelion, Shinji Ikari is transformed into various shapes, among them a diplocaulus and a hallucigenia.
- Diplocaulus appears in ARK: Survival Evolved.
- Diplocaulus appeared in the simulation video game Jurassic Park III: Park Builder.
- Diplocaulus can be created in Jurassic World: The Game as a common amphibian.
- Diplocaulus will be able created in Jurassic World: Alive as a common amphibian.