Alaska dinosaur tracks reveal a lush, wet environment

A large find of dinosaur tracks and fossilized plants and tree stumps in far northwestern Alaska provides new information about the climate and movement of animals near the time when they began traveling between the Asian and North American continents roughly 100 million years ago.

The findings by an international team of scientists led by paleontologist Anthony Fiorillo were published Jan. 30 in the journal Geosciences. Fiorillo researched in Alaska while at Southern Methodist University. He is now executive director of the New Mexico Museum of Natural History and Science.

University of Alaska Fairbanks geology professor Paul McCarthy, with the UAF Geophysical Institute and UAF College of Natural Science and Mathematics, was a leading contributor to the research. He and UAF graduate student Eric Orphys are among the eight co-authors.

Fiorillo and McCarthy are longtime collaborators.

"We've had projects for the last 20 years in Alaska trying to integrate sedimentology, dinosaur paleontology and the paleoclimate indicators," McCarthy said. "We've done work in three other formations -- in Denali, on the North Slope and in Southwest Alaska -- and they're about 70 million years old."

"This new one is in a formation that's about 90 to 100 million years old," he said.

Fiorillo said the additional age is notable.

"What interested us about looking at rocks of this age is this is roughly the time that people think of as the beginning of the Bering Land Bridge -- the connection between Asia and North America," he said. "We want to know who was using it, how they were using it and what the conditions were like."

Research into the paleoclimate can help scientists understand the warming world of today, the authors write.

"The mid-Cretaceous was the hottest point in the Cretaceous," said McCarthy, a sedimentologist and fossil soils specialist. "The Nanushuk Formation gives us a snapshot of what a high-latitude ecosystem looks like on a warmer Earth."

A rich find of evidence

The Nanushuk Formation is an outcropped layer of sedimentary rock 800 to 5,000 feet thick across the central and western North Slope. It dates to roughly 94 million to 113 million years ago in the mid-Cretaceous Period and about when the Bering Land Bridge began.

The fieldwork occurred in 2015-2017 and centered on Coke Basin, a circular geologic feature of the Nanushuk Formation. The basin is in the DeLong Mountains foothills along the Kukpowruk River, about 60 miles south of Point Lay and 20 miles inland from the Chukchi Sea.

In the area, Fiorillo and McCarthy found approximately 75 fossil tracks and other indicators attributed to dinosaurs living in a riverine or delta setting.

"This place was just crazy rich with dinosaur footprints," Fiorillo said.

One site stands out, Fiorillo said.

"We were at a spot where we eventually realized that for at least 400 yards we were walking on an ancient landscape," he said. "On that landscape we found large upright trees with little trees in between and leaves on the ground. We had tracks on the ground and fossilized feces."

They found numerous fossilized tree stumps, some 2 feet in diameter.

"It was just like we were walking through the woods of millions of years ago," he said.

The Nanushuk Formation encompasses rock of marine and non-marine characteristics and composition, but the authors' research focuses primarily on the non-marine sediments exposed along the upper Kukpowruk River.

"One of the things we did in our paper was look at the relative frequencies of the different kinds of dinosaurs," Fiorillo said. "What was interesting to us was that the bipedal plant eaters were clearly the most abundant."

Two-legged plant eaters accounted for 59% of the total tracks discovered. Four-legged plant eaters accounted for 17%, with birds accounting for 15% and non-avian, mostly carnivorous, bipedal dinosaurs at 9%.

"One of the things that was interesting is the relative frequency of bird tracks," Fiorillo said.

The authors point out that nearly half of North America's shorebirds breed in the warm months of today's Arctic. They suggest that the high number of fossil bird tracks along the Kukpowruk River indicates the warm paleoclimate was a similar driver for Cretaceous Period birds.

A wet and warm place

Carbon isotope analysis of wood samples led to a determination that the region received about 70 inches of precipitation annually. This record of increased precipitation during the mid-Cretaceous provides new data that supports global precipitation patterns associated with the Cretaceous Thermal Maximum, the authors write.

The Cretaceous Thermal Maximum was a long-term trend approximately 90 million years ago in which average global temperatures were significantly higher than those of today.

"The temperature was much warmer than it is today, and what's possibly more interesting is that it rained a lot," Fiorillo said. "The samples we analyzed indicate it was roughly equivalent to modern-day Miami. That's pretty substantial."

Of note is that the Alaska site investigated by Fiorillo and McCarthy was about 10 to 15 degrees latitude farther north in the mid-Cretaceous than it is today.

McCarthy's role as a fossil soils expert was to analyze old rocks and sediments to interpret the type of environment that existed at the time.

"We can say here's a river channel, here's a flood deposit, here's a levee, here's the floodplain, here's a swamp," he said. "And so if we're able to find tracks in that section, then you can sometimes say that a group of dinosaurs seems to have really liked being here as opposed to there."

Fiorillo said the site indicates there's much more work to be done.

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Decline in microbial genetic richness in the western Arctic Ocean

The Arctic region is experiencing climate change at a much faster rate than the rest of the world. Melting ice sheets, runoff from thawing permafrost and other factors are rapidly changing the composition of the Arctic Ocean's water. And that change is being experienced all the way down to the microbial level.

In a Concordia-led study published in the journal ISME Communications, researchers analyzed archival samples of bacteria and archaea populations taken from the Beaufort Sea, bordering northwest Canada and Alaska.

The samples were collected between 2004 and 2012, a period that included two years -- 2007 and 2012 -- in which the sea ice coverage was historically low.

The researchers looked at samples taken from three levels of water: the summer mixed layer, the upper Arctic water below it and the Pacific-origin water at the deepest level.

The study examined the microbes' genetic composition using bioinformatics and statistical analysis across the nine-year time span.

Using this data, the researchers were able to see how changing environmental conditions were influencing the organisms' structure and function.

The researchers found subtle but statistically significant changes in the communities they studied.

"We observed a general overall loss in diversity of species across all the different water masses," says David Walsh, a professor in the Department of Biology and the paper's corresponding author.

"We also saw changes in the composition of the microbial community, meaning there were different species after the 2007 sea ice minimum than before."

However, the periods of population richness decline changed between the ocean's layers of water.

Sudden decline in the fresher summer mixed water level, between 3-9 meters deep, was observed in 2005-2007.

The upper Arctic water, between 16-78 metres, saw declines in 2010-2012, while the deeper Pacific water layer, between 49-154 meters, experienced a two-step decline -- once between 2005-2007 and again between 2010-2012.

Small beginnings

The researchers are taking care not to overemphasize the results of their findings, saying the changes, while significant, remain slight.

But with the summer Arctic ice cover shrinking steadily year over year, the data does hint at possible trends that may be visible in upcoming population studies in more recent years.

"With the warming and freshening of the Arctic Ocean comes a decrease of nutrients that are important for photosynthesis, which produces the organic matter that serves as energy and carbon sources for the marine food web," Walsh explains.

"This shift risks strengthening what is known as the microbial loop, in which the energy and carbon that would normally go into higher trophic levels -- meaning zooplankton and then fish -- is rapidly recycled by microorganisms. This ecosystem is already dominated by microbial processes, which will only get stronger as this system continues."

"This study provides us with a baseline idea of what is happening in the Arctic," says co-author Arthi Ramachandran, PhD 23. "The Arctic is warming four times faster than the rest of the world, which makes it a fascinating ecosystem to study. The oceans are all interconnected, and the physical barriers of these oceans are becoming much less defined."

Looking into the ocean's warmer, fresher future

The researchers are now planning a metagenomic study that extends the time series to cover periods of even more intense sea ice minima.

They hope to fully sequence the organisms' genomes to further understand the microbial communities' diversity and function in the environment.

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Woolly mammoth movements tied to earliest Alaska hunting camps

Researchers have linked the travels of a 14,000-year-old woolly mammoth with the oldest known human settlements in Alaska, providing clues about the relationship between the iconic species and some of the earliest people to travel across the Bering Land Bridge.

Scientists made those connections by using isotope analysis to study the life of a female mammoth, named Élmayųujey'eh, by the Healy Lake Village Council.

A tusk from Elma was discovered at the Swan Point archaeological site in Interior Alaska.

Samples from the tusk revealed details about Elma and the roughly 1,000-kilometer journey she took through Alaska and northwestern Canada during her lifetime.

Isotopic data, along with DNA from other mammoths at the site and archaeological evidence, indicates that early Alaskans likely structured their settlements to overlap with areas where mammoths congregated.

Those findings, highlighted in the new issue of the journal Science Advances, provide evidence that mammoths and early hunter-gatherers shared habitat in the region.

The long-term predictable presence of woolly mammoths would have attracted humans to the area.

"She wandered around the densest region of archaeological sites in Alaska," said Audrey Rowe, a University of Alaska Fairbanks Ph.D. student and lead author of the paper.

"It looks like these early people were establishing hunting camps in areas that were frequented by mammoths."

The mammoth tusk was excavated and identified in 2009 by Charles Holmes, affiliate research professor of anthropology at UAF, and François Lanoë, research associate in archaeology at the University of Alaska Museum of the North.

They found Elma's tusk and the remains of two related juvenile mammoths, along with evidence of campfires, the use of stone tools, and butchered remains of other game.

All of this "indicates a pattern consistent with human hunting of mammoths," said Ben Potter, an archaeologist and professor of anthropology at UAF.

Researchers at UAF's Alaska Stable Isotope Facility then analyzed thousands of samples from Elma's tusk to recreate her life and travels.

Isotopes provide chemical markers of an animal's diet and location.

The markers are then recorded in the bones and tissues of animals and remain even after they die.

Mammoth tusks are well-suited to isotopic study because they grew throughout the ancient animals' lives, with clearly visible layers appearing when split lengthwise.

Those growth bands give researchers a way to collect a chronological record of a mammoth's life by studying isotopes in samples along the tusk.

Much of Elma's journey overlapped with that of a previously studied male mammoth who lived 3,000 years earlier, demonstrating long-term movement patterns by mammoths over several millennia.

In Elma's case, they also indicated she was a healthy 20-year-old female.

"She was a young adult in the prime of life. Her isotopes showed she was not malnourished and that she died in the same season as the seasonal hunting camp at Swan Point where her tusk was found," said senior author Matthew Wooller, who is director of the Alaska Stable Isotope Facility and a professor at UAF's College of Fisheries and Ocean Sciences.

The era in which Elma lived may have compounded the challenges posed by the relatively recent appearance of humans.

The grass- and shrub-dominated steppe landscape that had been common in Interior Alaska was beginning to shift toward more forested terrain.

"Climate change at the end of the ice age fragmented mammoths' preferred open habitat, potentially decreasing movement and making them more vulnerable to human predation," Potter said.

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Alaskan allies: Communities unite to protect the areas they love

Natural resource management decisions in protected areas impact more than the wildlife and landscapes they're charged to conserve. They also affect neighbors, who could otherwise hunt, build, or recreate as they choose on their own land. For decades, community members primarily voiced their opinions through brief and impersonal public comment periods. But an initiative led by environmental social scientists at the University of Illinois Urbana-Champaign is putting a new spin on neighborly communication.

"Historically, public land management agencies would offer brief periods where people could submit a remark that may or may not be considered and that typically wouldn't result in any meaningful dialogue," said Carena van Riper, associate professor in the Department of Natural Resources and Environmental Sciences in the College of Agricultural, Consumer and Environmental Sciences (ACES) at U. of I. "For more inclusive conservation to happen, there needs to be in-depth engagement, communication, and deliberation with diverse stakeholders. There's real benefit to engaging people."

Van Riper has been working toward a model of inclusive conservation for nearly a decade in the area surrounding Alaska's Denali National Park, partnering with the National Park System (NPS) to examine the values and viewpoints of neighbors on everything from conservation priorities to tourism impacts. She and her colleagues published results of their latest engagement efforts in Sustainability Science.

The study brought Denali neighbors together in a month-long online discussion forum designed to understand their views on the benefits and threats facing the area, as well as how land management agencies could better incorporate their perspectives.

Van Riper noted that residents come from all walks of life and have priorities that span protected area conservation, indigenous use, tourism, energy development, and others.

"Although it is important, conservation is just one of many priorities," she said. "We tried to equalize the power dynamic among interest groups and in how we framed the National Park Service and its role in defining life in Interior Alaska."

Residents were grouped according to a values assessment, with two groups of like-minded participants and one group representing a mix of values. This allowed the research team to test whether the value-basis of decision-making affected the ways that people learned from one another and engaged in collaborative dialogue.

"I went into this project worried because a lot of online dialogue tends to be very combative. But the most wonderful discussions unfolded with this group of people; they were always thoughtful and respectful to one another. They disagreed, but we never had to step in and intervene," said lead author Devin Goodson, a doctoral student working with van Riper. "Another one of the benefits of engaging online is people weren't forced to fully explain their thoughts in the moment, like you'd have to do during a short public comment session. The platform created a really well informed and constructive conversation."

After a period where participants got to know each other during focus groups, they were engaged through the Denali Discussion Forum, where the researchers posed a series of questions about the park and its management. Residents were expected to answer the questions and interact with other participants' answers on a weekly basis during the month-long program.

Goodson said the residents discussed many of the same benefits of living near Denali, though the groups differed in the emphasis they placed on particular benefits, which included access to wilderness, solitude, recreation, hunting and fishing grounds, and the pursuit of a subsistence lifestyle. Likewise, the groups emphasized slightly different threats, including tourism, competing interests, mismanagement, and climate change -- the latter was mentioned only by the mixed values group, which comprised a younger demographic. The groups diverged more strongly in their discussions on management solutions.

"We found that residents value the Alaskan landscape in a lot of ways and often identify common threats, but they come up with different ways to solve these issues. However, a common thread across the proposed solutions for resource managers was that people just wanted to feel like they were a part of the process in a meaningful way," Goodson said. "They're open to what that looks like, but they want to feel that the process overall is fair."

Co-author William Stewart in the Department of Recreation, Sport and Tourism at U. of I. added, "The NPS makes well-intentioned decisions, yet sometimes, residents of nearby communities feel like their voices aren't being heard. They need help. Social scientists have a toolkit for that. We engage community residents not as decision-makers, but as outsiders who could represent community voices to help facilitate dialogue with the park, and within the park service."

Armed with results from the Denali Discussion Forum, which were summarized weekly by the study team with input from participants, NPS can move ahead with more informed management decisions. And they can use a similar model to solicit input for future management actions.

But the lessons extend well beyond Denali and even the National Park System. Goodson said the study is an example of one way to give average people a say in the things that impact them every day in their environment.

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Southern Alaska's national forests key to meeting climate, conservation goals

Analyses of U.S. national forests led by Oregon State University scientists shows that increased protections for two Alaskan forests is a key to meeting climate and biodiversity goals.

In a paper published in AGU Advances, OSU College of Forestry researchers make the case that greater conservation efforts in the Tongass and Chugach national forests in southern Alaska are crucial because of their landscape integrity, high carbon stocks and wildlife habitat extent.

"More thoroughly safeguarding those forests from industrial development would contribute significantly to climate change mitigation and species adaptation in the face of the severe ecological disruption that's expected to occur over the next few decades as the climate rapidly gets warmer," said Oregon State's Bev Law, who co-led the study.

At 16.7 million acres, the Tongass is America's largest national forest. The Chugach is the second-largest at just under 7 million acres.

Not only are they the biggest national forests, they are the most intact, Law said, and provide habitat for iconic, keystone species such as the bald eagle, brown bear and gray wolf.

"Those forests are also cool and wet, with carbon stocks that are only minimally affected by wildfire, stocks that are likely to increase as the climate changes," she said. "Protecting the Tongass and Chugach is a high priority if we want to have a chance to attain global goals relating to climate and diversity of species."

Law and collaborators in the College of Forestry teamed up with researchers at Southern Oregon University, the Woodwell Climate Research Center and EcoSpatial Services L.L.C. to look at 152 national forests and compare them in terms of carbon density and accumulation, total biomass carbon stocks, habitat for eagles, bears and wolves, and landscape integrity -- defined as degree of modification by humans.

The authors report that almost 31% of all high-landscape-integrity area found in national forests -- areas with minimal or no human modification -- is in the Tongass and Chugach, at 25.3% and 5.6%, respectively.

Those forests also combine to account for nearly half of all bald eagle habitat available in national forests, 37% of brown bear habitat and 18% of gray wolf habitat -- no other location has more than 4% of the total wolf habitat found in the U.S. inventory of national forests. All three species were once widespread and abundant across much of North America.

"Forests play an incredibly important part in trying to mitigate climate change and support biodiversity," Law said. "For six decades, ecosystems on land have annually been removing roughly 30% of all the carbon dioxide humans have been putting into the atmosphere, and forests do most of that work. But intact forests with high carbon density and high biodiversity are disappearing at a frightening pace, lost to agriculture, logging and other industries, and development."

In addition to sequestering carbon and providing wildlife habitat, intact forests provide a range of ecosystem services, including helping to keep water clean, the authors note. And in the quest to establish nature-based climate solutions, public lands have outsized importance because they are more likely than private lands to afford more stable carbon storage.

Still, at present, federal forest lands are caught up in a numbers game, and conservation has some ground to make up on the scoreboard, Law said.

"National forests account for 76% of all federal forest land, but logging and other industrial activities are allowed throughout most of that, with only about 19% classified as reserved in one way or another from timber production," she said. "That means there is a substantial gap between current preservation and the preservation targets for protecting biodiversity and carbon stocks."

Ramping up protection in the Alaskan forests offers a big opportunity for closing that gap, the authors point out. Right now, 35% of the Tongass is protected at the two highest levels as categorized by the U.S. Geological Survey and the International Union for Conservation of Nature, and 57.6% of the Chugach.

"Those two forests have historically been wetter and cooler than most national forests, and over the next 100 years they are projected to have much larger increases in precipitation and much lower increases in maximum temperatures," Law said. "Combined with a relatively low occurrence of wildfire, that makes preserving these forests in their intact state highly possible -- if there is the political will to take bold action."

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Searching for ancient bears in an Alaskan cave led to an important human discovery

The first people to live in the Americas migrated from Siberia across the Bering land bridge more than 20,000 years ago. Some made their way as far south as Tierra del Fuego, at the tip of South America. Others settled in areas much closer to their place of origin where their descendants still thrive today.

In "A paleogenome from a Holocene individual supports genetic continuity in Southeast Alaska," published Friday in the journal iScience, University at Buffalo evolutionary biologist Charlotte Lindqvist and collaborators show, using ancient genetic data analyses, that some modern Alaska Natives still live almost exactly where their ancestors did some 3,000 years ago.

Lindqvist, PhD, associate professor of biological sciences in the UB College of Arts and Sciences, is senior author of the paper. In the course of her extensive studies in Alaska, she explored mammal remains that had been found in a cave in the state's southeast coast. One bone was initially identified as coming from a bear. However, genetic analysis showed it to be the remains of a human female.

"We realized that modern Indigenous peoples in Alaska, should they have remained in the region since the earliest migrations, could be related to this prehistoric individual," says Alber Aqil, a UB PhD student in biological sciences and the first author of the paper. This discovery led to efforts to solve this mystery, which DNA analyses are well suited to address when archeological remains are as sparse as these were.

Learning from an ancestor

The earliest peoples had already started moving south along the Pacific Northwest Coast before an inland route between ice sheets became viable. Some, including the female individual from the cave, made their home in the area that surrounds the Gulf of Alaska. That area is now home to the Tlingit Nation and three other groups: Haida, Tsimshian, and Nisga'a.

As Aqil and colleagues analyzed the genome from this 3,000-year-old individual -- "research that was not possible just 20 years ago," Lindqvist noted -- they determined that she is most closely related to Alaska Natives living in the area today. This fact showed it was necessary to carefully document as clearly as possible any genetic connections of the ancient female to present-day Native Americans.

In such endeavors, it is important to collaborate closely with people living in lands where archeological remains are found. Therefore, cooperation between Alaska Native peoples and the scientific community has been a significant component of the cave explorations that have taken place in the region. The Wrangell Cooperative Association named the ancient individual analyzed in this study as "Tatóok yík yées sháawat" (Young lady in cave).

Genetic continuity in Southeast Alaska persists for thousands of years

Indeed, Aqil and Lindqvist's research demonstrated that Tatóok yík yées sháawat is in fact closest related to present-day Tlingit peoples and those of nearby tribes along the coast. Their research therefore strengthens the idea that genetic continuity in Southeast Alaska has continued for thousands of years.

Human migration into North America, although it began some 24,000 years ago, came in waves -- one of which, about 6,000 years ago -- included the Paleo-Inuit, formerly known as Paleo-Eskimos. Importantly for understanding Indigenous peoples' migrations from Asia, Tatóok yík yées sháawat'sDNA did not reveal ancestry from the second wave of settlers, the Paleo-Inuit. Indeed, the analyses performed by Aqil and Lindqvist helped shed light on the continuing discussion of migration routes, mixtures among people from these different waves, as well as modern territorial patterns of inland and coastal people of the Pacific Northwest in the pre-colonial era.

Oral history links an ancient woman to people living in Southeast Alaska today

The oral origin narratives of the Tlingit people include the story of the most recent eruption of Mount Edgecumbe, which would place them exactly in the region by 4,500 years ago. Tatóok yík yées sháawat, their relative, therefore informs not just modern-day anthropological researchers but also the Tlingit people themselves.

Out of respect for the right of the Tlingit people to control and protect their cultural heritage and their genetic resources, data from the study of Tatóok yík yées sháawat will be available only after review of its use by the Wrangell Cooperative Association Tribal Council.

"It's very exciting to contribute to our knowledge of the prehistory of Southeast Alaska," said Aqil.

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