Fieldwork re-enacts life at the end of the “era of the dinosaurs”


A team of students, volunteers and staff from the University of Washington excavate the Flyby Trike Triceratops in northeastern Montana. Credit: Rachel Ormiston / Burke Museum / University of Washington

A team of paleontologists from Washington University 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 surrounding rock in the fossil preparation lab.

The four dinosaur fossils are: the ilium – or hip bone – 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; a pelvis, toe claw, and limbs of another theropod that could be a rare ostrich mimic Anzu, or possibly a new species; and one Triceratops specimen composed of his skull and other fossilized bones. Three of the four dinosaurs were all found nearby on Bureau of Land Management land that is currently leased to a rancher.

Flyby Trike Excavation Montana

University of Washington paleontologist Kelsie Abrams examines Flyby Trike fossils during excavations in northeastern Montana. Credit: Rachel Ormiston / Burke Museum / University of Washington

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 unearth these dinosaurs. . The fossils were found in the Hell Creek Formation, a geologic formation that dates from the later part of Cretaceous Period, 66 to 68 million years ago. Typical paleontological excavations involve the excavation of a known fossil. However, the Hell Creek Project is an ongoing research collaboration of paleontologists around the world studying life just before, during, and after the K-Pg mass extinction that killed all dinosaurs except birds. The Hell Creek Project is unique in that it samples all of the plant and animal life found in the rock formation in an unbiased manner.

“Each fossil we collect helps us refine our vision of the last dinosaur-dominated ecosystems and the earliest mammal-dominated ecosystems,” said Gregory Wilson Mantilla, professor of biology at UW and curator of vertebrate paleontology at Burke. Museum. “With these, we can better understand the processes involved in the loss and origin of biodiversity and the fragility, collapse and assembly of ecosystems.”

Hell Creek Formation

The Hell Creek geological formation. Credit: Andrea Godinez / Burke Museum / University of Washington

All dinosaurs except the Triceratops will be prepared in the Burke Museum’s fossil preparation lab this fall and winter. The Triceratops fossil remains at the site because the excavation team continued to find more and more bones during the excavation and need an additional season of land to extract other bones that may be related to the surrounding rock. The team plans to complete the excavation in the summer of 2022.

Named “Flyby Trike” in honor of the breeder who first identified the dinosaur as it flew over his plane over his ranch, the team discovered the dinosaur’s steering wheel, the bones of the horn, individual rib bones, lower jaw, teeth, and occipital condyle bone – nicknamed “the trailer hitch,” which is the ball in the back of the skull that connects to the vertebrae in the neck. The team estimates that around 30% of this individual’s skull bones have been discovered to date, and more potential bones will be excavated next year.

Flyby Trike Trailer Hitch Bones

A close-up view of the Flyby Trike’s occipital condyle bone – nicknamed “the trailer hitch” – the bullet at the back of the skull that connects to the vertebrae in the neck. Credit: Rachel Ormiston / Burke Museum / University of Washington

The Flyby Trike was found in hardened mud, with the bones scattered over each other in a different way from how the bones would be arranged in a living animal. These clues indicate that the dinosaur probably died in a floodplain, then mixed after its death by being moved by a flood or river system, or perhaps moved by a scavenger like a T. rex, before fossilizing. In addition, the Flyby Trike is one of the last Triceratops alive before the mass extinction of K-Pg. Burke’s paleontologists estimate that he lived less than 300,000 years before the event.

“Prior to this year’s excavation, part of the Flyby Trike collar and a frontal horn were collected and then prepared by volunteer preparers in the fossil preparation lab. The collar has been put together in many pieces and put together in a fantastic way by volunteers. After confusing the flying part together, it was discovered that the specimen is probably an older “grandparent” TriceratopsSaid Kelsie Abrams, head of the Burke Museum’s paleontological preparation lab, who also participated in the fieldwork this summer. “The triangular bones along the ruff, called the ‘occipital spikes,’ are completely fused and almost unrecognizable on the specimen, compared to the sharp and noticeable triangular shape seen in younger individuals. Additionally, the frontal horn curves downward rather than upward, and this feature has also been reported in older animals. “

Theropode Ilium opening jacket

Kelsie Abrams, head of the Burke Museum’s paleontological preparation lab, opens the field jacket of a theropod ilion. Credit: Timothy Kenney / Burke Museum / University of Washington

Amber pods and seeds have also been found with the Flyby Trike. These findings allow paleobotanists to determine which plants coexisted Triceratops, what the dinosaurs may have eaten, and what the overall ecosystem in Hell Creek looked like before mass extinction.

“The remains of plant fossils from this period are crucial to our understanding of the ecosystem at large. Not only can plant material tell us what these dinosaurs might have been eating, plants can more broadly tell us what their surroundings looked like, ”said Paige Wilson, UW Earth and Earth Sciences graduate student. space. “Plants are the basis of the food chain and a crucial part of the fossil record. It’s exciting to see this new material found so close to vertebrate fossils!

Museum visitors can now see paleontologists removing rock from the first of four dinosaurs – theropod hips – in Burke’s paleontological preparation lab. Additional fossils will be prepared in the coming weeks. The four dinosaurs will be held in trust for the public on behalf of the Bureau of Land Management and will become part of the collections of the Burke Museum.

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