BOZEMAN – A study by a Montana State University alumna featured this week on the cover of the journal Science reveals that forebears of modern birds nested in polar regions of the Arctic alongside other dinosaurs nearly 73 million years ago.
The evidence lies in the fossilized bones of adult and hatchling birds recovered from deposits at the bottom of ancient riverbeds in the Prince Creek Formation of Alaska’s North Slope. The fossils date to well before the mass extinction 66 million years ago of three-quarters of Earth’s plant and animal species, including non-avian dinosaurs.
The fossil collection represents the earliest proof of birds nesting in polar ecosystems and the first evidence that this polar nesting behavior originated before the mass extinction. The recovered bones from at least three species show traits consistent with modern birds, as well as with extinct diving and gull-like birds.
“Birds have existed on Earth for 150 million years, and now we know birds have been nesting in the Arctic for at least half the time they’ve existed on the planet. It’s obviously a very important strategy for them,” said the paper’s lead author Lauren Wilson (formerly Lauren Keller), a 2021 graduate of the paleontology program in MSU’s Department of Earth Sciences in the College of Letters and Science, now a doctoral student at Princeton University.
Though the world was much warmer in the Late Cretaceous than it is today, scientists believe the Prince Creek Formation, which then was situated about 10 to 15 degrees farther north than today at a north latitude of 80 to 85 degrees, likely experienced wintry conditions, including four months of continuous darkness, freezing temperatures and snowfall. They don’t know whether the birds that nested in the Arctic migrated to warmer climates in winter, Wilson said, but do know those birds would have benefited from the abundant resources available in the ecosystem with nearly six months of continuous daylight in the warmer months of the year.
Wilson conducted the research on the Arctic bird fossils while pursuing her master’s degree at the University of Alaska Fairbanks, where she chose to study at the recommendation of an MSU mentor Eric Metz, now the collections manager at the Museum of the Rockies. She was excited to work on Arctic dinosaurs when she arrived in Fairbanks in the summer of 2021 but hadn’t identified a specific project, so she agreed to look at recently excavated bird material to make some initial identifications and look for a thesis topic. She says she had no idea how extensive the collection was or how important it was going to be.
“When you start looking at half of a little bone and half of another little bone, you don’t expect them to hold so much information,” said Wilson, adding that the collection is notable because it includes more than 50 bones with representation from almost every part of the bird skeleton, many of them preserved in 3D.
Many of the Prince Creek Formation birds share skeletal traits with modern ducks and geese, suggesting they may be closely related. Some had beaks full of true teeth, which differ from the teeth of modern geese and ducks, which are made of keratin rather than enamel and dentin.
The baby bird bones were identified by their small size and porous texture, which resembles sponge. The texture indicated that the bones were still in the process of growing rapidly, and since birds reach maturity very rapidly, the scientists know that those bones were from very young birds.
Wilson said her undergraduate education and experiences at MSU prepared her well for her master’s research. It included field work and lab experience for professor David Varricchio; mentorship from numerous faculty and graduate students; and development of phylogenetic analysis skills in a macroevolution class taught by assistant professor of earth sciences Christopher Organ. She said that when it came time to submit the Arctic bird paper to “a big, scary journal like Science,” she solicited help framing the study from Organ, who is one of the paper’s co-authors.
“I got involved to help interpret and think about the evolutionary and ecological ramifications of the discovery,” said Organ, who explained that birds help structure ecosystems by dispersing other organisms, such as invertebrates or plant seeds. “Especially in remote islands or the Arctic or Antarctic, birds are unique players in ecosystem creation. Finding fossils of young birds at these ancient high latitudes rewrites the timeline of avian Arctic ecology and highlights just how early birds likely influenced dispersal of biodiversity into some of Earth’s most extreme terrestrial environments.”
In addition to Organ, three more co-authors of the paper have ties to MSU: alumni Greg Erickson and Jacob Gardner and former Museum of the Rockies volunteer John Wilson. In addition, the bird fossils were gathered by University of Alaska Fairbanks field crews led by Patrick Druckenmiller, who earned his master’s degree at MSU in 1998 as a student of paleontologist Jack Horner.
“The delicate bird fossils used in this study were the product of more than a decade of challenging fieldwork in the Alaska Arctic,” Druckenmiller said. “Ultimately, we assembled one of the largest Cretaceous bird collections in North America – an unexpected but amazing result.”
MSU Photo by Adrian Sanchez-Gonzalez