BOZEMAN — For more than 40 years, an area of Cretaceous rock exposures in northwest Montana’s Teton County has been the site of exciting fossil discoveries, including ones by paleontologists from Montana State University’s Museum of the Rockies. Now, it has been named an International Geoheritage Site.
The designation identifies such sites “as being of the highest scientific value. They are sites that served to develop the science of geology, particularly its early history,” according to the International Commission on Geoheritage.
The science organization awarded the designation to the “Cretaceous Dinosaur Nesting Grounds of the Willow Creek Anticline” at its international congress over the summer in South Korea.
“Fossils unearthed at the Willow Creek Anticline helped change the way people think about dinosaurs,” said John Scannella, curator of paleontology at the Museum of the Rockies. “These discoveries have shaped our view of what dinosaurs were like as living animals.”
In 1978, Marion Brandvold discovered tiny bones in outcrops of the Cretaceous Two Medicine Formation near Choteau. That summer, paleontologists Jack Horner and Bob Makela visited the Brandvolds’ rock shop in Bynum, Montana, and identified the bones as those of baby duck-billed dinosaurs. They visited the site where the bones were discovered and found many more baby dinosaur bones, along with dinosaur eggshells. They discovered that the little dinosaur fossils were in nests, the first reported from the Western hemisphere.
Studies revealed the bones belonged to a new species of duck-billed dinosaur that nested together in groups and cared for their young. For much of the 20th century, dinosaurs had been thought of as lumbering, lizard-like animals. Those surprising findings in Montana suggested dinosaurs were more dynamic and social than previously suspected.
The duck-billed dinosaurs were named Maiasaura peeblesorum — Maiasaura meaning “good mother reptile” and peeblesorum honoring the Peebles family, on whose land the discoveries were made. In 1985, Maiasaura became Montana’s state fossil.
The Willow Creek Anticline, where the fossils were found, is a large fold in the Cretaceous rocks of the region. Near the Maiasaura nesting ground, many other fossil finds have been made, including the famous Egg Mountain site, which revealed eggs and embryos of bird-like theropod dinosaurs.
“Many of the fossil localities of the Willow Creek Anticline are now part of Museum of the Rockies’ Beatrice R. Taylor Paleontology Research Area, where exploration into these incredible animals and their environment continues each year,” Scannella said.
For more information about fossils in Montana, visit, www.museumoftherockies.org. To learn more about the Willow Creek Anticline and other Geoheritage sites, visit https://iugs-geoheritage.org/geoheritage_sites/the-cretaceous-dinosaur-nesting-grounds-of-the-willow-creek-anticline/.
