It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon County, Montana, USA.

New remains are under description, and tracks from Maryland and Virginia, also in the US, have been attributed to animals similar to Zephyrosaurus.

He found the new genus to represent a previously unknown lineage of hypsilophodont (a taxon now considered not natural), similar in some respects to Hypsilophodon.

[1] Because of the fragmentary nature of the type, and lack of additional remains, Zephyrosaurus had not attracted much attention until recently, when two separate events brought it more recognition.

[2] Then, Stanford et al. (2004) published on dinosaur tracks from the Patuxent Formation of Maryland and Virginia, which they named Hypsiloichnus marylandicus and attributed to an animal akin to Zephyrosaurus based on the proportions of the hands and feet.