Zephyrosaurus was a small ornithopod dinosaur which lived in Montana during the middle Cretaceous Period. The first fossils of this animal were discovered by Charles R. Schaff, who worked at Harvard University’s Museum of Comparative Zoology. Schaff was prospecting for bones at a place called Wolf Creek Canyon, located in Carbon County, Montana when he discovered a fragmentary skeleton consisting of a partial upper jaw, a few vertebrae, and pieces of some ribs. The rocks where these fossils were found belonged to the Cloverly Formation, which dated to about 110 million years ago.

In 1980, Dr. Hans-Deiter Sues of the Smithsonian Institution named it Zephyrosaurus schaffi, “Charles Schaff’s lizard of the Western Wind”. The holotype specimen is housed within the collections of the Museum of Comparative Zoology (collections ID code: MCZ 4392). Hans-Deiter Sues classified Zephyrosaurus as a “hypsilophodont”. In the past, the hypsilophodonts (named in reference to the British dinosaur Hypsilophodon) were classified as any small or medium-sized ornithopod dinosaur which still possessed teeth in the premaxilla; by contrast, dryosaurs, iguanodonts, and hadrosaurs did not have teeth in the fronts of their jaws. However, this classification is now believed to be polyphyletic, so most scientists don’t use the name Hypsilophodontidae anymore. Zephyrosaurus is thought to have been a close relative of Parksosaurus and Orodromeus, and thus would place it within the family Thescelosauridae.

The fragmentary skull which Charles Schaff discovered measured about 5 inches (13 centimeters) long. Based upon the size of the skull, it’s believed that Zephyrosaurus reached 6 feet long. However, it’s possible, due to its large eye sockets, small teeth, and pushed-in snout, that this individual may be a juvenile, and that the adult was substantially larger. Considering that Zephyrosaurus is now classified within the family Thescelosauridae, and considering that Thescelosaurus itself reached 12 feet long, and considering that the fragmentary skull which we have of Zephyrosaurus might be from a juvenile, then it is possible that Zephyrosaurus also grew to be at least 12 feet long as well. However, until more specimens are found, we cannot know for sure. In 2003, it was reported that a group of seven Zephyrosaurus skeletons were in the collections of the Sam Noble Oklahoma Museum of Natural History in Norman, Oklahoma, and were currently undergoing study, but no news has been relayed since then of what findings had been made. The following year in 2004, it was published that footprint trackways have been found in Maryland and Virginia, which had been ascribed to Zephyrosaurus or an animal very similar to it.

Below is a drawing which I made of Zephyrosaurus, made with No. 2 pencil on printer paper.

Zephyrosaurus. © Jason R. Abdale (July 24, 2021)

For more info, please check out the following sources:

Sues, Hans-Dieter (1980). “Anatomy and relationships of a new hypsilophodontid dinosaur from the Lower Cretaceous of North America”. Palaeontographica Abteilung A., volume 169, issue 1-3 (1980). Pages 51–72.

Kutter, Martha M. (2003). “New material of Zephyrosaurus schaffi (Dinosauria: Ornithischia) from the Cloverly Formation (Aptian-Albian) of Montana”. Journal of Vertebrate Paleontology, volume 23 (supplement to number 3: Abstracts of Papers) (September 2003). Page 69A.

Stanford, Ray; Weems, Robert E.; Lockley, Martin G. (2004). “A new dinosaur ichnotaxon from the Lower Cretaceous Patuxent Formation of Maryland and Virginia”. Ichnos, volume 11, issue 3-4 (2004). Pages 251-259.

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