A team of paleontologists from the 91̽�� and its 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 .

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; a pelvis, toe claw and limbs from another theropod that could be a rare ostrich-mimic Anzu, or possibly a new species; and a Triceratops specimen consisting of its skull and other fossilized bones. Three of the four dinosaurs were all found in close proximity on Bureau of Land Management land that is currently leased to a rancher.

In July 2021, a team of volunteers, paleontology staff, K-12 educators who were part of the and students from 91̽��and other universities worked together to excavate these dinosaurs. The fossils were found in the , a geologic formation that dates from the latest portion of Cretaceous Period, 66 to 68 million years ago. Typical paleontological digs involve excavating one known fossil. However, the Hell Creek Project is an ongoing research collaboration of paleontologists from around the world studying life right before, during and after the that killed off all dinosaurs except birds. The Hell Creek Project is unique in that it is sampling all plant and animal life found throughout the rock formation in an unbiased manner.

“Each fossil that we collect helps us sharpen our views of the last dinosaur-dominated ecosystems and the first mammal-dominated ecosystems,” said , a 91̽��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.”

All of the dinosaurs except the Triceratops will be prepared in the Burke Museum’s fossil preparation laboratory this fall and winter. The Triceratops fossil remains on the site because the dig team continued to find more and more bones while excavating and needs an additional field season to excavate any further bones that may be connected to the surrounding rock. The team plans to finish excavation in the summer of 2022.

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 team estimates approximately 30% of this individual’s skull bones have been found to date, with more potential bones to be excavated next year.

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. In addition, the Flyby Trike is one of the last Triceratops living before the K-Pg mass extinction. Burke paleontologists estimate it lived less than 300,000 years before the event.

“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 participated in this summer’s field work. “The triangular bones along the frill, called ‘epi occipitals,’ are completely fused and almost unrecognizable on the specimen, as compared to the sharp, noticeable triangular shape seen in younger individuals. In addition, the brow horn curves downwards as opposed to upwards, and this feature has been reported to be seen in older animals as well.”

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.

“Plant fossil remains from this time period are crucial for our understanding of the wider ecosystem. Not only can plant material tell us what these dinosaurs were perhaps eating, but plants can more broadly tell us what their environment looked like,” said Paige Wilson, a 91̽��graduate student in Earth and space sciences. “Plants are the base 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 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.

For high resolution images, videos and interviews, contact burkepr@uw.edu.

A published Aug. 11 in the Proceedings of the Royal Society B by researchers at the 91̽�� and Stony Brook University reports on how bats and pepper plants in Central America have coevolved to help each other survive.

The team — led by , a 91̽��professor of biology and curator of mammals at the Burke Museum of Natural History and Culture — focused on the complex mixture of volatile organic compounds, or VOCs, produced by fruits on pepper plants in the genus Piper at prime ripeness. The study showed how these VOCs may have evolved to attract scent-oriented, short-tailed fruit bats from the genus Carollia, who then eat the fruits and excrete the seeds into the landscape.

Plant–animal interactions have captured the attention of biologists for centuries, and are key to maintaining the biodiversity of tropical ecosystems. The dispersal syndrome hypothesis — an explanation of how mutually beneficial relationships between plants and fruit-eating animals may lead to coevolution — proposes that, when animals are effective seed dispersers, they may select for fruit traits, including size, color and odor, that match their sensory abilities, such as vision and olfaction. But few studies have tested this hypothesis for complex traits like fruit scents. This research provides one of the first tests of bat-driven, fruit scent evolution.

The study is based on data collected during fieldwork at La Selva Biological Station in Costa Rica. There, Piper is highly diverse, with more than 50 recognized species. It is also a location where three Carollia species — C. castanea, C. sowellii and C. perspicillata — are some of the most abundant bats year-round and coexist with approximately 62 other bat species.

The team spent hundreds of hours searching and collecting ripe fruits from Piper to extract and quantify the VOCs that make up their fragrant scent. They also collected fecal samples from live bats and then released them back into the wild to determine which Piper species the bats were eating and how much. In addition, the researchers conducted behavioral experiments with wild bats where they offered options of unripe fruits enhanced with the most common VOCs found in local Piper plants. Video cameras and microphones recorded the bats’ feeding behaviors and echolocation calls.

The team found Piper fruit scent bouquets were complex and diverse. The authors identified and quantified 249 VOCs in ripe fruit scents across 22 Piper species. Some compounds were found in the fruit scent of most species — like alpha-caryophyllene, which has a spicy scent like cinnamon or cloves. Others, like 2-heptanol, were only found in a few Piper species. The diet experiments showed that, while the three Carollia fruit bat species varied in their reliance on Piper as a food source, all consumed a lot of a few Piper species, and a little of many others. Surprisingly, this was not related to how abundant the Piper species are at La Selva, so the bats must choose Piper fruits based on other characteristics and not just how well represented they are across the landscape. The team’s behavioral experiments provided some clues to what might be happening: Bats preferred samples spiked with 2-heptanol, a VOC found in the fruit scents of the Piper species they eat the most.

“These findings suggest bats use specific chemicals in the fruit scent bouquet not only to select ripe fruits, but to find the specific Piper species that make up the bulk of their diet,” said Santana, who is co-lead author on the study. “By helping them communicate with the bats, these chemical signals are likely a component of a dispersal syndrome in these plants.”

Through statistical and evolutionary analyses of the data on fruit scent chemistry and bat diet, the team further demonstrated that the evolutionary patterns of chemical diversity and the presence of specific compounds in Piper fruit scents is associated with greater bat consumption and scent preferences. This highlights the potential effect of bat fruit consumption on the evolution of fruit chemistry, a relationship that contributes to the extreme diversity of tropical fruiting plants worldwide.

“Flying in the dark means bats cannot find ripe fruit by sight, but rely on olfaction instead,” said co-author , a professor at Stony Brook University. “Olfaction is the bridge between the plant signal and bat fruit consumption, and finding the specific VOCs bats respond to opens the door to matching olfactory receptor genes to important VOCs, which has been impossible until now.”

Understanding the relationship between bats and pepper plants not only contributes to knowledge about coevolution of these species, but also has benefits for rainforest habitat conservation. Piper are some of the first plants to grow in forest gaps and edges, and Carollia ― as key dispersers of Piper seeds ― can help restore plant life in logged areas.

“Our current and future work is identifying the odorant receptors that allow the bats to detect the fruit scents. This will allow us to link the ecology and evolution of these relationships with the physiological mechanisms,” said co-author , a 91̽��professor of biology.

Co-lead author on the paper is former 91̽��postdoctoral researcher Zofia Kaliszewska. Other co-authors are 91̽��doctoral alum Leith Leiser-Miller, M. Elise Lauterbur at the University of Arizona and Jessica Arbour at Middle Tennessee State University. The research was funded by the National Science Foundation.

For high-resolution images, video and interviews, contact burkepr@uw.edu.

A published June 16 in Biotropica by a team of researchers at the 91̽��, the 91̽��Burke Museum of Natural History and Culture, WWF Hong Kong and the University of Colombo has provided an important road map to conserving rough-nosed horned lizards in Sri Lanka.

Rough-nosed horned lizards, or Ceratophora aspera, are small lizards that live in Sri Lankan rainforests and aren’t found anywhere else in the world. Characterized by the prominent horn in males, rough-nosed horned lizards live in moist, humid microhabitats in rainforests and palm groves. These lizards are particularly well-suited to understand the consequences of rainforest habitat destruction, climate change and the pet trade, as they are found throughout the lowland rainforests of Southwestern Sri Lanka. By analyzing the certain types of mutations in the genome of these lizards, the team was able to determine how geography and historical events impact the distribution of the remaining wild populations of rough-nosed horned lizards. Recent 91̽��graduate Shanelle Wikramanayake led the study as part of her undergraduate work, and is now completing her master’s degree at California State University, Northridge.

The team acquired DNA from the rough-nosed horned lizards by a catch-and-release approach of capturing wild lizards and taking tissue samples from the tips of their tails before releasing them back to the wild, which minimizes stress to the animals. Samples were taken across eight forests representing four forest groups from July through September 2018 and 2019, respectively. The remaining tissue samples will be housed along with photos of the lizards at the Department of Zoology and Environment Sciences at the University of Colombo. In addition, the DNA analysis from the team’s work is also available online, where the samples and analysis are available for other researchers around the globe to study.

In addition to habitat destruction, nonnative species like cats and chickens eat these lizards, causing further harm to them and other prey animals. The team recommends a conservation strategy that considers the population structure, history and ecology of rough-nosed horned lizards to preserve genetic diversity.

The results from the DNA analysis found rough-nosed horned lizards are separated by distance into four forest groups: Southern Lowlands, Sabaragamuwa Hills, Central Highlands and Kithulgala. With the Sri Lankan government pledging to restore rainforest habitats, the results from the study can help inform guidelines for forest landscape restoration. For example, the similarities in populations and close geographic proximity between the lizards living in the Hiyare and Kottawa forest reserves in the Southern Lowlands forest group is a great candidate for habitat restoration. The two populations could be reconnected, increasing the chances for interbreeding, which could result in a stronger gene pool for future generations and less vulnerability to extinction.

“I hope this study brings attention to the unique and obscure biodiversity in the rainforests of Sri Lanka that require urgent conservation action,” said Wikramanayake. “It’s important to consider the genetic diversity in populations across their range when looking at conservation planning and strategies. This principle should also be considered in other forest ecosystems, where conservationists are planning restoration and habitat connectivity at landscape scales.”

In addition to these lizards, the researchers are currently considering extending this work to other animals and other regions of Sri Lanka of high conservation value. In Sri Lanka, approximately 14% of mammals, 6.5% of birds, 75% of reptiles and 29% of flowering plant species aren’t found anywhere else in the world. The methods of DNA analysis in this study not only inform conservation planning in Sri Lanka, but they also can be applied to species living in other rainforests that are at risk, including Madagascar, Borneo and the Amazon.

“I am proud and impressed with the hard work and passion that Shanelle Wikramanayake put into her project,” said Adam Leaché, 91̽��biology professor and Burke Museum curator of herpetology and genetic resources. “The Burke Museum is lucky to recruit such amazing undergraduates.”

For high-resolution images, video and interviews, contact burkepr@uw.edu.

GenBank accession numbers: MT955097 through MT955112 and SRR12586520 through SRR12586535

A new published Feb. 24 in the journal Royal Society Open Science documents the earliest-known fossil evidence of primates.

A team of 10 researchers from across the U.S. analyzed several fossils of Purgatorius, the oldest genus in a group of the earliest-known primates called plesiadapiforms. These ancient mammals were small-bodied and ate specialized diets of insects and fruits that varied by species. These newly described specimens are central to understanding primate ancestry and paint a picture of how life on land recovered after the Cretaceous-Paleogene extinction event 66 million years ago that wiped out all dinosaurs — except for birds — and led to the rise of mammals.

, a 91̽�� professor of biology and curator of vertebrate paleontology at the UW’s , co-led the study with of Brooklyn College and the City University of New York. The team analyzed fossilized teeth found in the Hell Creek area of northeastern Montana. The fossils, which are now part of the collections at the University of California Museum of Paleontology, are estimated to be 65.9 million years old, about 105,000 to 139,000 years after the mass extinction event. Based on the age of the fossils, the team estimates that the ancestor of all primates —including plesiadapiforms and today’s primates such as lemurs, monkeys and apes — likely emerged by the Late Cretaceous and lived alongside large dinosaurs.

“It’s mind blowing to think of our earliest archaic primate ancestors,” said Wilson Mantilla. “They were some of the first mammals to diversify in this new post-mass extinction world, taking advantage of the fruits and insects up in the forest canopy.”

The fossils include two species of Purgatorius: Purgatorius janisae and a new species described by the team named Purgatorius mckeeveri. Three of the teeth found have distinct features compared to any previously known Purgatorius species and led to the description of the new species.

Purgatorius mckeeveri is named after Frank McKeever, who was among the first residents of the area where the fossils were discovered, and also the family of John and Cathy McKeever, who have since supported the field work where the oldest specimen of this new species was discovered.

“This was a really cool study to be a part of, particularly because it provides further evidence that the earliest primates originated before the extinction of non-avian dinosaurs,” said co-author Brody Hovatter, a 91̽��graduate student in Earth and space sciences. “They became highly abundant within a million years after that extinction.”

“This discovery is exciting because it represents the oldest dated occurrence of archaic primates in the fossil record,” said Chester. “It adds to our understanding of how the earliest primates separated themselves from their competitors following the demise of the dinosaurs.”

Co-author on the study was the late who was a professor emeritus at the University of California, Berkeley and former director of the UC Museum of Paleontology. Additional co-authors are Jason Moore and Wade Mans of the University of New Mexico; Courtney Sprain of the University of Florida; William Mitchell of Minnesota IT Services; Roland Mundil of the Berkeley Geochronology Center; and Paul Renne of UC Berkeley and the Berkeley Geochronology Center. The research was funded by the National Science Foundation, the UC Museum of Paleontology, the Myhrvold and Havranek Charitable Family Fund, the UW, the CUNY and the Leakey Foundation.

For high resolution images and interviews, contact burkepr@uw.edu.

Led by Wesley Knapp of the North Carolina Natural Heritage Program, a group of 16 experts from across the United States — including , a 91̽�� professor of biology and curator of the UW’s — collaborated on this first-of-its-kind project to document the extinct plants of the continental United States and Canada. Their findings Aug. 28 in Conservation Biology.

The team found that most plant extinctions occurred in the western United States, where the vegetation was minimally documented before widespread European settlement. Since many extinctions likely occurred before scientists analyzed an area, it is likely the 65 documented extinctions underestimate the actual number of plant species that have been lost. Previous studies documented far fewer plant extinctions on the North American continent.

In Washington state, the team found two confirmed extinctions: the thistle milk-vetch, or , and the pale bugseed, or . While neither of these Eastern Washington species were ever abundant, their disappearance is likely due to the human impact of changing land use. This has also dramatically reduced the populations of countless other species, many of which are likely to follow these into extinction, unless efforts to protect what remains of native habitat are stepped up.

“Preventing extinction is the lowest bar for conservation success we can set, yet we are not always successful,” said Knapp. “This study started as an academic question but later developed into an opportunity to learn from what we have lost. By studying the trends and patterns of plants that have already gone extinct, hopefully we can learn how to prevent plant extinction going forward.”

Of the 65 documented extinctions in the report, 64% were known only from a single location. While conservation often focuses on protecting entire landscapes, this finding points to the importance of small-scale site protection to prevent extinctions. Extinct species are still being described from old herbarium specimens, underscoring the importance of continued documentation of the flora and supporting museum collections like the .�� Corispermum pallidum, one of the species extinct in Washington, was first collected in 1893. Yet the species wasn’t formally “discovered” until much later when it was first described as a new species posthumously in 1995. Only a handful of herbarium specimens exist today.�� The Burke has three, including one of the two collections from 1893 and the last known collection from 1931.

“There is no living memory of either of these species today,” Olmstead said. “Herbarium collections record our flora as it was historically and provide documentation of change, and loss, over time, whether through direct human impact, or indirectly through climate change and the impact it will have on plants. Documenting extinction is difficult, but herbarium records can say where and when a species was last observed and guide the search for surviving members.”

This work also highlights the need for collaborative science in addressing large-scale conservation issues. The team of 16 botanists from across the United States includes experts with state and federal government agencies, numerous botanical gardens, museums, nonprofit organizations, regional conservation groups and academic institutions. To answer the overarching question of what exists and where, the team of experts cross-checked thousands of records to ensure accuracy, discovering that botanical gardens occasionally harbored the last of an extremely rare species and may not have been aware of it.

Plants serve as the foundation for most terrestrial ecosystems. The predicted rise of extinction rates over the next century adds even greater urgency to the need to document plant extinctions. Anne Frances, lead botanist at NatureServe, said, “In most cases, we can stop plants from going extinct, we just need the resources and commitment to do so.”

For high-resolution images, videos and interviews, contact burkepr@uw.edu.

Adapted from a by the North Carolina Department of Natural and Cultural Resources.

A new study led by paleontologists at the 91̽�� and its indicates that the earliest evidence of mammal social behavior goes back to the Age of Dinosaurs.

The evidence, Nov. 2 in the journal Nature Ecology & Evolution, lies in the fossil record of a new genus of — a small, rodent-like mammal that lived during the Late Cretaceous of the dinosaur era — called Filikomys primaevus, which translates to “youthful, friendly mouse.” The fossils are the most complete mammal fossils ever found from the Mesozoic in North America. They indicate that F. primaevus engaged in multi-generational, group-nesting and burrowing behavior, and possibly lived in colonies. Study co-authors — including lead author , a 91̽��graduate student in biology, and senior author , a 91̽��professor of biology and curator of vertebrate paleontology at the Burke Museum — analyzed several fossils, all about 75.5 millioin years old, and extracted from a well-known dinosaur nesting site called Egg Mountain in western Montana.

Fossil skulls and skeletons of at least 22 individuals of F. primaevus were discovered at Egg Mountain, typically clustered together in groups of two to five, with at least 13 individuals found within a 30 square-meter area in the same rock layer. Based on how well preserved the fossils are, the type of rock they’re preserved in, and F. primaevus’ powerful shoulders and elbows — which are similar to today’s living burrowing animals — Weaver, Wilson Mantilla and co-authors hypothesize these animals lived in burrows and were nesting together. Furthermore, the animals found were a mixture of multiple mature adults and young adults, suggesting these were truly social groups as opposed to just parents raising their young.

“It was crazy finishing up this paper right as the stay-at-home orders were going into effect — here we all are trying our best to socially distance and isolate, and I’m writing about how mammals were socially interacting way back when dinosaurs were still roaming the Earth!” said Weaver. “It is really powerful, I think, to see just how deeply rooted social interactions are in mammals. Because humans are such social animals, we tend to think that sociality is somehow unique to us, or at least to our close evolutionary relatives, but now we can see that social behavior goes way further back in the mammalian family tree. Multituberculates are one of the most ancient mammal groups, and they’ve been extinct for 35 million years, yet in the Late Cretaceous they were apparently interacting in groups similar to what you would see in modern-day ground squirrels.”

Previously, scientists thought social behavior in mammals first emerged after the mass extinction that killed off the dinosaurs, and mostly in the Placentalia — the group of mammals humans belong to, which all carry the fetus in the mother’s uterus until a late stage of development. But these fossils show mammals were socializing during the Age of Dinosaurs, and in an entirely different and more ancient group of mammals — the multituberculates.

“These fossils are game changers,” said Wilson Mantilla. “As paleontologists working to reconstruct the biology of mammals from this time period, we’re usually stuck staring at individual teeth and maybe a jaw that rolled down a river, but here we have multiple, near complete skulls and skeletons preserved in the exact place where the animals lived. We can now credibly look at how mammals really interacted with dinosaurs and other animals that lived at this time.”

Co-authors are and at Montana State Univeristy, at Yale University and Meng Chen of Nanjing University. The research was funded by the National Science Foundation, Doris O. and Samuel P. Welles Research Fund, the 91̽��and the Burke Museum.

For high resolution images and interviews, contact burkepr@uw.edu.

Officially one year after the opening of the new Burke Museum and in honor of Indigenous Peoples Day, the , , and the Washington State Arts Commission () are honored to announce a new outdoor installation called Guests of the Great River that greets guests as you arrive at the museum’s east entrance. Created by Chinook Indian Nation Chairman and artist and artist Adam McIsaac, the piece consists of 11 large-scale bronze paddles representing the arrival of a Chinookan canoe carrying cultural heroes of the Columbia River region, and with them the knowledge they embody.

Made possible thanks to funding from the Washington State Arts Commission in partnership with the UW, these larger-than-life bronze paddles were hand carved in wood by Johnson and McIsaac, then 3D scanned and enlarged in scale up to 11 feet, leaving the viewer in awe. The paddles are carved in a variety of Chinook styles and sizes—some of which are hundreds of years old — that are still made and used by communities today. The notch on the top is distinct to the Columbia River and was used to grab hold of cottonwood roots along the river banks.

Guests from the Great River is installed in the shape of a canoe, representing the cultural protocol of canoe families landing on neighbors’ shores. The paddles are lifted in a traditional form of peaceful greeting and respect to the museum and its guests. Different stories and figures are portrayed on each paddle. These heroes have come to celebrate and enhance the educational opportunities that the Burke brings to the Pacific Northwest and the world.

Watch a video interview with the artists .

“People that live here on this land without any knowledge of this information are really missing a big part of what makes this place itself,” Johnson said. “My interest in sharing these stories and teachings is that people will treat the place differently, these aboriginal lands of ours—and the aboriginal lands of our neighbors—if people were to really understand these stories.”

“This is a magnificent artwork that honors the original peoples of this land,” Karen Hanan, ArtsWA executive director, said. “We’re very pleased to include Guests from the Great River as part of Washington’s State Art Collection.

Each day the paddles’ shadows take one stroke across the entry plaza of the museum, perpetually in motion. “Every five minutes it’s changing from the way the sun’s hitting it. While I’m really excited to see it here today, I’m really excited to see it change over seasons and years,” Johnson said.

“All of the art on the Northwest Coast is about bringing people together, sharing, and inspiring,” McIsaac said. “That’s what I have gotten from my relationship with Tony and his people. And that is as much to be celebrated as the art is.”

For high resolution images, videos, and interviews, contact burkepr@uw.edu.

A new published April 30 in the identified three factors critical in the rise of mammal communities since they first emerged during the Age of Dinosaurs: the rise of flowering plants, also known as angiosperms; the evolution of tribosphenic molars in mammals; and the extinction of non-avian dinosaurs, which reduced competition between mammals and other vertebrates in terrestrial ecosystems.

Previously, mammals in the Age of Dinosaurs were thought to be a relatively small part of their ecosystems and considered to be small-bodied, nocturnal, ground-dwelling insectivores. According to this long-standing theory, it wasn’t until the about 66 million years ago, which wiped out all non-avian dinosaurs, that mammals were then able to flourish and diversify. An astounding number of fossil discoveries over the past 30 years has challenged this theory, but most studies looked only at individual species and none has quantified community-scale patterns of the rise of mammals in the Mesozoic Era.

Co-authors are Meng Chen, a 91̽�� alumnus and current postdoctoral researcher at Nanjing University; , a 91̽�� biology professor and curator of paleobotany at the UW’s ; and , a 91̽��associate professor of biology and Burke Museum curator of vertebrate paleontology. The team created a Rubik’s Cube-like structure identifying 240 “eco-cells” representing possible ecological roles of mammals in a given ecospace. These 240 eco-cells cover a broad range of body size, dietary preferences, and ways of moving of small-bodied mammals. When a given mammal filled a certain type of role or eco-cell, it filled a spot in the ‘Rubik’s Cube.’ This method provides the first comprehensive analysis of evolutionary and ecological changes of fossil mammal communities before and after K-Pg mass extinction.

“We cannot directly observe the ecology of extinct species, but body size, dietary preferences and locomotion are three aspects of their ecology that can be relatively easily inferred from well-preserved fossils,” said Chen. “By constructing the ecospace using these three ecological aspects, we can visually identify the spots filled by species and calculate the distance among them. This allows us to compare the ecological structure of extinct and extant communities even though they don’t share any of the same species.”

The team analyzed living mammals to infer how fossil mammals filled roles in their ecosystems. They examined 98 small-bodied mammal communities from diverse biomes around the world, an approach that has not been attempted at this scale. They then used this modern-day reference dataset to analyze five exceptionally preserved mammal paleocommunities ― two Jurassic Period and two Cretaceous Period communities from northeastern China, and one Eocene Epoch community from Germany. Usually Mesozoic Era mammal fossils are incomplete and consist of fragmentary bones or teeth. Using these remarkably preserved fossils enabled the team to infer ecology of these extinct mammal species, and look at changes in mammal community structure during the last 165 million years.

The team found that, in current communities of present-day mammals, ecological richness is primarily driven by vegetation type, with 41 percent of small mammals filling eco-cells compared to 16 percent in the paleocommunities. The five mammal paleocommunities were also ecologically distinct from modern communities and pointed to important changes through evolutionary time. Locomotor diversification occurred first during the Mesozoic, possibly due to the diversity of microhabitats, such as trees, soils, lakes and other substrates to occupy in local environments. It wasn’t until the Eocene that mammals grew larger and expanded their diets from mostly carnivory, insectivory and omnivory to include more species with diets dominated by plants, including fruit. The team determined that the rise of flowering plants, new types of teeth and the extinction of dinosaurs likely drove these changes.

Before the rise of flowering plants, mammals likely relied on conifers and other seed plants for habitat, and their leaves and possibly seeds for food. By the Eocene, flowering plants were both diverse and dominant across forest ecosystems. Flowering plants provide more readily available nutrients through their fast-growing leaves, fleshy fruits, seeds and tubers. When becoming dominant in forests, they fundamentally changed terrestrial ecosystems by allowing for new modes of life for a diversity of mammals and other forest-dwelling animals, such as birds.

“Flowering plants really revolutionized terrestrial ecosystems,” said Strömberg. “They have a broader range of growth forms than all other plant groups ― from giant trees to tiny annual herbs ― and can produce nutrient-rich tissues at a faster rate than other plants. So when they started dominating ecosystems, they allowed for a wider variety of life modes and also for much higher ‘packing’ of species with similar ecological roles, especially in tropical forests.”

Tribosphenic molars ― complex multi-functional cheek teeth ― became prevalent in mammals in the late Cretaceous Period. Mutations and natural selection drastically changed the shapes of these molars, allowing them to do new things like grinding. In turn, this allowed small mammals with these types of teeth to eat new kinds of foods and diversify their diets.

Lastly, the K-Pg mass extinction event that wiped out all dinosaurs except birds 66 million years ago provided an evolutionary and ecological opportunity for mammals. Small body size is a way to avoid being eaten by dinosaurs and other large vertebrates. The mass extinction event not only removed the main predators of mammals, but also removed small dinosaurs that competed with mammals for resources. This ecological release allowed mammals to grow into larger sizes and fill the roles the dinosaurs once had.

“The old theory that early mammals were held in check by dinosaurs has some truth to it,” said Wilson. “But our study also shows that the rise of modern mammal communities was multifaceted and depended on dental evolution and the rise of flowering plants.”

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For more information contact Andrea Godinez with the 91̽��Burke Museum at burkepr@uw.edu.

Burke Museum story .

Antarctica wasn’t always a frozen wasteland. About 250 million years ago, it was covered in forests and rivers, and the temperature rarely dipped below freezing. It was also home to diverse wildlife, including early relatives of the dinosaurs. Scientists have just discovered the newest member of that family — an iguana-sized reptile whose genus name, Antarctanax, means “Antarctic king.”

“This new animal was an archosaur, an early relative of crocodiles and dinosaurs,” said Brandon Peecook, a researcher and lead author of a in the describing the new species. “On its own, it just looks a little like a lizard, but evolutionarily, it’s one of the first members of that big group. It tells us how dinosaurs and their closest relatives evolved and spread.”

Collected during a 2010-2011 expedition to Antarctica led by senior author , professor of biology at the 91̽�� and curator of vertebrate paleontology at the UW’s , the fossil specimen consists of portions of the backbone, limbs and skull. The specimen is now part of the permanent collections at the Burke Museum and is one of more than 300 vertebrate fossils from Antarctica in its collection, collected over the course of four expeditions and resulting in one of the largest Antarctic vertebrate fossil collections in the country. During the Burke’s most recent Antarctic expedition in 2017-2018 Sidor led his team back to Graphite Peak, the site where Antarctanax had been found, which was also where the first vertebrate fossils in Antarctica were discovered in 1967.

Although the new specimen is an incomplete skeleton, paleontologists still have a good feel for the animal, named Antarctanax shackletoni — the latter part a nod to polar explorer . Based on its similarities to other fossil animals, the researchers surmise that Antarctanax was a carnivore that hunted bugs, amphibians, and relatives of early mammals.

The most interesting thing about Antarctanax, the authors say, is where and when it lived.

“The more we find out about prehistoric Antarctica, the weirder it is,” says Peecook, who was a doctoral student in the 91̽��Department of Biology at the time the fossil was collected and is now also a research associate at the Burke Museum. “We thought that Antarctic animals would be similar to the ones that were living in southern Africa, since those landmasses were joined back then. But we’re finding that Antarctica’s wildlife is surprisingly unique.”

About two million years before Antarctanax lived — the blink of an eye in geologic time — Earth underwent its largest mass extinction. Climate change, caused by volcanic eruptions, killed 90 percent of animal life. The years immediately after that extinction event were an evolutionary free-for-all. With the slate wiped clean by the mass extinction, new groups of animals vied to fill the gaps. The archosaurs, including dinosaurs, were among the groups that experienced enormous growth.

“Before the mass extinction, archosaurs were only found around the equator, but after it, they were everywhere,” said Peecook. “And Antarctica had a combination of these brand-new animals and stragglers of animals that were already extinct in most places — what paleontologists call ‘dead walking.’ You’ve got tomorrow’s animals and yesterday’s animals, cohabiting in a cool place,” he added.

“Fossil exploration in Antarctica is really difficult, given all of the logistics involved. But since so little work has been done the potential for making important new discoveries is high — and that’s what Antarctanax represents,” said Sidor. “The same rocks that yielded Antarctanax also yield some of the earliest mammal relatives from after the mass extinction.”

The fact that scientists have found Antarctanax helps bolster the idea that Antarctica was a place of rapid evolution and diversification after the mass extinction.

“The more different kinds of animals we find, the more we learn about the pattern of archosaurs taking over after the mass extinction,” said Peecook. “Antarctica is one of those places on Earth, like the bottom of the sea, where we’re still in the very early stages of exploration. Antarctanax is our little part of discovering the history of Antarctica.”

Co-author on the paper is of the University of the Witwatersrand in Johannesburg and the Iziko South African Museum.

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For more information, contact Andrea Godinez at burkepr@uw.edu.

Adapted from a by the Field Museum.

Botanists at the 91̽��’s have created a much-needed second edition of the “Flora of the Pacific Northwest.” Published by the 91̽��Press, took five years to complete and is the first update on Pacific Northwest vascular plant diversity and distributions since the book was first published in 1973. In the past 45 years, much has changed: The second edition documents the doubling of nonnative species in the Pacific Northwest, the addition of 1,000 taxa — including species, subspecies and varieties — to the region’s flora, and the reclassification or renaming of 40 percent of the taxa in the first edition.

The original “Flora of the Pacific Northwest” became an instant classic for its innovative style providing species descriptions in the identification keys and for its comprehensive illustrations of nearly all treated taxa. Students rely on it as an essential primer, while veteran botanists and natural resource managers use it as the definitive reference for the region’s flora.

“This book enables us to be better stewards, we know what’s here, whether it’s common or rare, or invasive,” said , collection manager for the at the Burke Museum. “It enhances our ability to preserve plant diversity in our region for future generations.”

This completely revised and updated edition captures the advances in vascular plant systematics since the first edition. These advances, together with significant changes in plant nomenclature, the description of taxa new to science from the region, and the recent documentation of new native and nonnative species in the Pacific Northwest, required a thorough revision of this authoritative work.

“Flora of the Pacific Northwest” covers all of Washington, the northern half of Oregon, Idaho north of the Snake River Plain, the mountainous portion of western Montana, and the southern portion of British Columbia. It accounts for wild-growing native and introduced vascular plants falling within those boundaries and includes:

• Treatment of 5,545 taxa, with more than 1,100 taxa added to this edition
• Illustrations for 4,716 taxa, including 1,382 new for this edition
• More than 700 newly documented nonnative taxa in the Pacific Northwest
• Nomenclature changes for more than 40 percent of the taxa included in the first edition

These enhancements make this new edition the most comprehensive reference on Pacific Northwest vascular plants for professional and amateur botanists, ecologists, rare plant biologists, plant taxonomy instructors, land managers, nursery professionals and gardeners.

The 1,100 new taxa consist mainly of existing native and nonnative species newly documented in the region, as well as a number of taxa new to science. Many of the new regional records were collected during the herbarium’s annual forays held throughout the Pacific Northwest.

“With the recent revision of ‘,’ and the soon-to-be-completed ‘Flora of Oregon,’ up to date floristic treatments are now available for the entire West Coast of the U.S.,” said , 91̽��biology professor and curator of the 91̽��Herbarium at the Burke Museum.

The new illustrations are in the style of the 3,000 original illustrations, by illustrators Jeanne R. Janish and John Ramely, found in the 1973 edition of the “Flora.”

Crystal Shin, a scientific illustrator and the primary illustrator for the revision, worked to match the style of the original illustrations so the more than 1,300 new illustrations she created seamlessly fit.

“Before inking, I study the style and techniques that Jeanne used on a similar species,” said Shin. “I like her work very much and my ink drawing style is pretty close to hers.”

Shin started the illustration process with a plant specimen by reviewing the specimen’s characteristics with one of the Burke Museum botanists. Together they determined which parts of the plant to include in the illustration. Shin then used a microscope and magnifying glass to examine the plant’s details, specifically its length of hairs, textures, marks, veins, shapes and more. After studying the plant, she proceeded with the illustration process of pencil sketching and then inking. Project staff then scanned, edited and archived the illustrations for later placement alongside the text.

It took approximately two hours to complete each illustration before being placed on the page in the book.

The newest edition of “Flora of the Pacific Northwest” can be purchased for $75.00 at the University Bookstore, local bookstores, and book retailers across the country and .

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For high-resolution images and interviews, contact burkepr@uw.edu or uwpmktg@uw.edu.