In the late 1970s, Montana couple John and Marion Branvold operated a rock shop in Bynum, Montana. While not running this operation, they often explored the area for fossils. One place they searched was a ranch owned by the Peebles family near Choteau. During one fossil-hunting trip here, Marion collected several small bones on a four-foot-wide knob of land.
Meanwhile, Jack Horner, a native of Shelby, Montana was working as a fossil preparator at Princeton University. For his four-week vacation in 1978 he decided to go back to his home state and search for dinosaur fossils with longtime friend and high school teacher Bob Makela.
Jack Horner and the Discovery of Dinosaurs in Conjunction with Nests and Eggs
During their travels around Montana searching for fossils, Horner and Makela stopped by the Branvold rock shop. They met Marion and identified several fossils on display, prompting Marion to go home and bring back more specimens. After Horner and Makela identified the bones as those from a baby duck-billed dinosaur, Branvold took the fossil hunters into her home and showed them the specimens from Choteau, which Horner also identified as fossil dinosaurs.
With this exciting discovery, Horner called his boss Don Baird at Princeton and secured not only a vacation extension in order to further investigate the fossils, but also money to pay for his expenses.
Horner and Makela then visited the Peebles ranch site, examining the rocks of the Two Medicine Formation laid down during the Cretaceous Period about 75-80 million years ago. After digging through the fossil-rich knob of land, the team made the stunning realization that what they were exploring was a dinosaur nest. This was the first time a dinosaur nest had ever been found that contained baby animals, rather than just eggs.
As Horner and Makela were making their groundbreaking discovery, Marion’s daughter-in-law Laurie Trexler found a skull nearby. Using this as the type specimen, Horner and Makela named the dinosaur Maiasaura (meaning "caring mother lizard" or "good mother lizard") peeblesorum (after the Peebles family).
The Nature of Maiasaura, the "Good Mother Lizard"
Horner went on to lead excavations resulting in the discovery of thousands of Maiasaura fossils, represented by eggs, embryos, babies, juveniles and adults. One bone bed, known as Egg Mountain, contained numerous nests and associated body fossils. Horner’s team also made the first-ever discovery of dinosaur adults associated with their nests, eggs, and juveniles.
This rich fossil record allowed Horner and other scientists to learn a lot about Maiasaura. The fact that adult Maisaura specimens were found near nests and juveniles means that adults likely cared for their young, much like birds do.
The nests were about six feet across and located about 30 feet apart. They could hold two dozen eggs the size of grapefruits. Maiasaura hatchlings were about a foot long, while adults grew to 30 feet long, eight feet tall, and a weight of several tons.
Maiasaura was a duck-billed dinosaur, a type of herbivorous creature that also includes Hadrosaurus. It was a social animal, nesting in colonies and traveling in herds numbering in the thousands.
Students Lead Efforts to Recognize Montana's State Fossil
In the mid 1980s, Ben Veach of the Montana State Council of Rocks and Minerals began a campaign to recognize Maiasaura as Montana’s official state fossil. Sixth-grade teacher Helen Peterson learned of this effort and encouraged her students to become involved. They wrote letters to state officials and distributed petitions to other Montana schools, collecting more than 8,000 student signatures from 60 schools.
Soon, Representative Orval Ellison introduced a bill naming Maiasaura as the state fossil. When the day for voting on the bill came, more than 100 students and other supporters went to the state capitol, sharing dinosaur-themed songs, speeches, pictures, and even cookies with state legislators.
These officials unanimously voted yes on the bill, and on February 22, 1985, Governor Ted Schwinden signed the bill into law at Mrs. Peterson’s school.
Sources
Horner, John and James Gorman. 1988. Digging Dinosaurs. Workman Publishing.
Montanakids.com website.
Kevin Schindler - I have worked at scientific institutions for more than 20 years written more than 200 articles about science, history, and baseball.
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