Fruitadens, scientifically known as "Fruitadens haagarorum," is classified as a member of the group of basal ornithischian dinosaurs. The name "Fruitadens" is derived from the locality of its discovery, the Fruita paleontological site in Colorado, USA. It lived during the Late Jurassic period, approximately 150 million years ago.

The discovery of Fruitadens fossils in the Morrison Formation has significantly contributed to our understanding of the diversity of small-bodied dinosaurs during the Jurassic.

Fruitadens was a small dinosaur, estimated to have measured around 2 to 3 feet (0.6 to 0.9 meters) in length. As a basal ornithischian, it shared certain characteristics with other early members of the ornithischian group, such as a beak-like mouth and a lightweight, bipedal posture.

Fruitadens exhibited anatomical similarities to Heterodontosaurus, featuring relatively short arms and long distal sections of the legs (feet and shins). Its lower jaws had an enlarged canine-like tooth, creating a corresponding gap in the upper jaw. Unlike Echinodon, there was no enlarged tooth in the upper jaw. Interestingly, Fruitadens had a small peg-like tooth positioned in front of the canine-like tooth. Unlike most other heterodontosaurids, Fruitadens had replacement teeth in its jaws. Additionally, its hind limb bones were hollow, resembling those of small theropod dinosaurs. Phylogenetically, Fruitadens appears to have been more closely related to Heterodontosaurus rather than Echinodon, despite being closer in time to the latter.

The limited fossil evidence makes it challenging to reconstruct Fruitadens' complete physical appearance accurately. However, its classification within the ornithischian group provides valuable insights into its overall body structure.