While Missouri is not widely recognized as a major dinosaur fossil hotspot, it holds a unique and significant position in the study of prehistoric life. The state’s geological history, particularly in its southeastern region, has preserved evidence of ancient ecosystems, offering rare glimpses into a time when dinosaurs roamed North America.
The Iconic Missouri Dinosaur
Missouri’s most notable dinosaur, and its official state dinosaur, is Parrosaurus missouriensis. This creature was a type of hadrosaur, commonly referred to as a “duck-billed dinosaur,” known for its distinctive snout. Initially, paleontologists mistakenly identified it as a sauropod, a long-necked dinosaur, due to the large size of its tail vertebrae. Subsequent re-evaluation clarified its true classification as a plant-eating hadrosaur.
Parrosaurus missouriensis was a substantial herbivore, estimated to reach lengths of approximately 30 to 35 feet. It weighed between 2 to 4 tons, comparable to the size of a modern elephant, and stood about 10 to 11 feet tall. This dinosaur possessed a complex dental system with over 1,000 teeth, well-suited for grinding tough vegetation. A unique feature among North American hadrosaurs was its large thumb spike, a primitive characteristic that other species had lost over time.
This particular species holds significance because it is one of the few dinosaur species found on the eastern side of the ancient Western Interior Seaway. This vast inland sea once divided North America during the Late Cretaceous period, and Parrosaurus missouriensis’s presence provides crucial information about dinosaur populations and their geographical spread.
The Discovery and Its Significance
The initial discovery of Parrosaurus missouriensis fossils occurred in 1942 on the Chronister family farm near Glen Allen in Bollinger County, Missouri. The family stumbled upon large, fossilized bones, which Geologist Dan R. Stewart recognized as dinosaur remains.
Stewart sent the bones to the Smithsonian Institution, where Dr. C.W. Gilmore of the U.S. Geological Survey undertook their classification. Gilmore initially named the dinosaur Neosaurus missouriensis in 1945 but quickly changed it to Parrosaurus missouriensis later that year, as the previous name was already in use. For decades, the site saw limited activity until the 1980s when Bruce Stinchcomb purchased the property, aiming to preserve its paleontological heritage.
Systematic excavations began in the 1990s under the direction of paleontologist Guy Darrough, leading to the discovery of a juvenile skeleton. In 2017, Dr. Pete Makovicky of the University of Minnesota and the Field Museum joined the effort, which culminated in the announcement in 2021 of multiple adult Parrosaurus missouriensis specimens. This site represents Missouri’s only known dinosaur locality and is believed to be a “mass death locality,” suggesting a herd of dinosaurs perished together. Such a find offers insights into the behavior, growth, and possible herd structures of these ancient animals.
Missouri’s Prehistoric World
During the Late Cretaceous period, approximately 95 to 70 million years ago, Missouri’s environment was considerably different from today. The region experienced a warmer climate, ranging from warm temperate to subtropical conditions, remaining conducive to diverse life forms.
Southeastern Missouri, part of what is known as the Mississippi Embayment, was submerged under an extension of the Gulf of Mexico. This created a coastal landscape characterized by wetlands, swamps, and oxbow lakes, providing abundant water sources and lush vegetation for large herbivores like Parrosaurus missouriensis.
The flora of Late Cretaceous Missouri was rich and varied, with flowering plants undergoing significant diversification. The landscape would have featured an abundance of plants similar to modern magnolias, sassafras, roses, redwoods, and willows. Broad-leaved evergreen forests and conifers were prevalent, forming dense habitats that could support large plant-eating dinosaurs.