Hypsibema missouriensis

Lore & Background

The species was first described as a sauropod by Gilmore and Stewart in 1945, a classification later deemed erroneous. It was initially named Neosaurus missouriensis, then renamed Parrosaurus missouriensis because 'Neosaurus' was preoccupied. In 1979, Donald Baird and John R. Horner moved it to the genus Hypsibema. In the late 1970s, geologist Bruce L. Stinchcomb purchased the property, and test excavations in the 1980s led to the conclusion that H. missouriensis was actually a hadrosaur. Thomas Holtz has suggested reverting to Parrosaurus, and in 2018 some paleontologists decided Parrosaurus was a valid genus.

Reader's Guide

Hypsibema missouriensis holds significance as one of the few official state dinosaurs and as the only dinosaur remains ever found in Missouri. Its discovery at the Chronister Dinosaur Site in 1942 was the first known dinosaur find in the state, and the site has since yielded remains of other dinosaurs, fish, turtles, and plants, including teeth of a tyrannosauroid and dromaeosaur bone fragments. The species' identification history reflects scientific uncertainty: initially misidentified as a sauropod, it was later reclassified as a hadrosaur. The designation as Missouri's state dinosaur in 2004, after a bill passed the legislature and was approved by the governor, highlights its cultural and educational role. The remains housed at the Smithsonian Institution and later excavations by the Field Museum of Natural History and the Sainte Genevieve Museum Learning Center underscore its ongoing scientific importance.

Did You Know?

• The bones were discovered in 1942 by the Chronister family while digging a cistern, and the Smithsonian bought thirteen tail vertebrae for US$50, which was used to buy a cow.
• Missouri became the seventh U.S. state to designate an official state dinosaur when Hypsibema missouriensis was approved in 2004.
• The Chronister Dinosaur Site has also yielded teeth of a tyrannosauroid and bone fragments of a dromaeosaur.