A team of paleontologists from the University of Washington and its Burke Museum of Natural History and Culture excavated four dinosaurs in northeastern Montana this summer. All fossils will be brought back to the Burke Museum where the public can watch paleontologists remove the surrounding rock in the fossil preparation laboratory.
The four dinosaur fossils are: the ilium—or hip bones—of an ostrich-sized theropod, the group of meat-eating, two-legged dinosaurs that includes Tyrannosaurus rex and raptors; the hips and legs of a duck-billed dinosaur; 
In July 2021, a team of volunteers, paleontology staff, K-12 educators who were part of the DIG Field School program and students from UW and other universities worked together to excavate these dinosaurs. The fossils were found in the Hell Creek Formation, a geologic formation that dates from the latest portion of Cretaceous Period, 66 to 68 million years ago.
“Each fossil that we collect helps us sharpen our views of the last dinosaur-dominated ecosystems and the first mammal-dominated ecosystems,” said Gregory Wilson Mantilla, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum. “With these, we can better understand the processes involved in the loss and origination of biodiversity and the fragility, collapse and assembly of ecosystems.”
Called the “Flyby Trike” in honor of the rancher who first identified the dinosaur while he was flying his airplane over his ranch, the team has uncovered this dinosaur’s frill, horn bones, individual rib bones, lower jaw, teeth and the occipital condyle bone—nicknamed the “trailer hitch,” which is the ball on the back of the skull that connects to the neck vertebrae
The Flyby Trike was found in hardened mud, with the bones scattered on top of each other in ways that are different from the way the bones would be laid out in a living animal. These clues indicate the dinosaur likely died on a flood plain and then got mixed together after its death by being moved around by a flood or river system, or possibly moved around by a scavenger like a T. rex, before fossilizing.
“Previous to this year’s excavations, a portion of the Flyby Trike frill and a brow horn were collected and subsequently prepared by volunteer preparators in the fossil preparation lab. The frill was collected in many pieces and puzzled together fantastically by volunteers. Upon puzzling the frill portion together, it was discovered that the specimen is likely an older ‘grandparent’ triceratops,” said Kelsie Abrams, the Burke Museum’s paleontology preparation laboratory manager who also led this summer’s field work.
Amber and seed pods were also found with the Flyby Trike. These finds allow paleobotanists to determine what plants were living alongside Triceratops, what the dinosaurs may have eaten, and what the overall ecosystem was like in Hell Creek leading up to the mass extinction event.
Museum visitors can now see paleontologists remove rock from the first of the four dinosaurs—the theropod hips—in the Burke’s paleontology preparation laboratory. Additional fossils will be prepared in the upcoming weeks. All four dinosaurs will be held in trust for the public on behalf of the Bureau of Land Management and become a part of the Burke Museum’s collections.