Hippodraco
The holotype of "Hippodraco", UMNH VP 20208, was discovered in 2004 by Andrew R. C. Milner. It is a fragmentary specimen including a fragmented skull and dentary teeth, vertebrae (dorsal, caudal and cervical), a right humerus, a right scapula, a left ischium, a right tibia, a right femur, and left metatarsals. It was later named in 2010 by Andrew T. McDonald, James I. Kirkland, Andrew R. C. Milner, Scott K. Madsen, Donald D. DeBlieux, Jennifer Cavin and Lukas Panzarin. The generic name "Hippodraco" is a combination of the Greek word "hippos" ("horse") and the Latin word "draco" ("dragon"). It refers to the elongated shape of the skull, which resembles a horse skull. The specific name "scutodens" is a combination of the Latin words "scutum" (meaning shield) and "dens" (meaning tooth), and it references the shield-shaped dentary tooth crowns. UMNH VP 20208 was unearthed from the Yellow Cat Member of the Cedar Mountain Formation, Utah, at a site known as "Andrew's Site", dating from the Valanginian stage in the Early Cretaceous period. "Hippodraco" is a relatively small iguanodontid, with the holotype reaching in length. Holtz estimated its weight between . However, a large orbital in the skull indicates that the specimen is immature. The left side of the skull is well preserved, although the right side is very fragmented. The left dentary is preserved on the skull along with teeth, which, have shield-shaped crowns. The lacrimal bone closely resembles those of "Dakotadon" and "Theiophytalia". Vertebrae indicates a characteristic iguanodont body shape. Most of the body remains are gracile, such as the right humerus and scapula, the right tibia and femur are fragmented, having irregular surfaces. The nearly-complete metatarsus is very similar to those of "Camptosaurus" and "Iguanodon". In 2010 and 2011 cladistic analyses of McDonald and colleagues, "Hippodraco" has been recovered as a basal member of the Styracosterna and its closest relative was "Theiophytalia". The holotype of "Hippodraco" was unearthed from the Upper Yellow Cat Member of the Cedar Mountain Formation. Contemporaneous fauna from the Upper Yellow Cat include the fellow ornithopod "Cedrorestes", sauropods ("Cedarosaurus" and "Moabosaurus"), theropods ("Martharaptor" and "Nedcolbertia"), the nodosaurid "Gastonia", and the giant dromaeosaurid "Utahraptor". Other dromaeosaurids with fragmentary remains are also known from the formation: an indeterminate eudromaeosaur (UMNH VP 20209) and an indeterminate velociraptorine (UMNH VP 21752).
Discovery
Hippodraco (meaning "horse dragon") is a genus of iguanodontian ornithopod dinosaur from the Early Cretaceous Cedar Mountain Formation of Utah, United States.