Yellowstone Times

For over four decades, a significant area of Cretaceous rock exposures in northwest Montana has been the site of remarkable fossil discoveries. These findings have now led to the area's designation as an International Geoheritage Site. The honor was awarded by the International Commission on Geoheritage, which identifies such sites "as being of the highest scientific value."

The specific site recognized is the "Cretaceous Dinosaur Nesting Grounds of the Willow Creek Anticline," as announced at an international congress held in South Korea over the summer. John Scannella, curator of paleontology at Montana State University's Museum of the Rockies, remarked on the importance of these discoveries: “Fossils unearthed at the Willow Creek Anticline helped change the way people think about dinosaurs. These discoveries have shaped our view of what dinosaurs were like as living animals.”

The story began in 1978 when Marion Brandvold discovered tiny bones within outcrops of the Cretaceous Two Medicine Formation near Choteau. That summer, paleontologists Jack Horner and Bob Makela identified these bones as belonging to baby duck-billed dinosaurs during a visit to Brandvold's rock shop in Bynum, Montana. Their investigation led to further discoveries, including more baby dinosaur bones and eggshells found in nests — a first for the Western hemisphere.

These studies revealed that these fossils belonged to a new species called Maiasaura peeblesorum, meaning "good mother reptile," named after the Peebles family on whose land they were found. This discovery challenged previous perceptions by suggesting that dinosaurs were dynamic and social creatures rather than lumbering lizard-like animals.

The Willow Creek Anticline also includes Egg Mountain, another important site where eggs and embryos of bird-like theropod dinosaurs have been discovered. According to Scannella, “Many of the fossil localities of the Willow Creek Anticline are now part of Museum of the Rockies’ Beatrice R. Taylor Paleontology Research Area.”

For additional details about fossils in Montana or information about Geoheritage sites like Willow Creek Anticline, interested individuals can visit www.museumoftherockies.org or https://iugs-geoheritage.org/geoheritage_sites/the-cretaceous-dinosaur-nesting-grounds-of-the-willow-creek-anticline/.