Paranthodon is a stegosaurian dinosaur genus that inhabited the region now known as South Africa during the Early Cretaceous period, around 139 to 131 million years ago. Unearthed in 1845, it represents one of the earliest discoveries of stegosaurians. Fossils attributed to Paranthodon consist of a partial skull, isolated teeth, and fragments of vertebrae, all recovered from the Kirkwood Formation.

Despite Franz Nopcsa correctly identifying Paranthodon as a stegosaur, numerous others initially misinterpreted the partial remains of this genus as belonging to an ankylosaur, which is another type of armored dinosaur but with significant differences. It wasn't until 1981 when another paleontologist named Peter Galton conclusively demonstrated that Paranthodon was indeed a stegosaur and not an ankylosaur.

Paranthodon, a smaller relative of larger stegosaurids like Stegosaurus, was estimated by Thomas R. Holtz Jr. to measure around 5.0 meters (16.4 feet) in length and weigh between 454 and 907 kilograms (1,001 and 2,000 pounds). Its snout, while elongated, is not excessively so and features a convex top. The rear section of the premaxilla is both long and wide, and it boasts sizable external nares. The teeth exhibit a prominent primary ridge. The preserved fossilized nasal and maxillary bones are relatively intact, and there's also a partially preserved premaxilla. The partial snout bears resemblance to Stegosaurus due to its large posterior premaxillary process and palate extension.