Announcing our 2021 DIG field program!

We are currently planning to resume the DIG Field School in the summer of 2021! We are planning our program for July 29–August 2, 2021. Applications open March 1, 2021. Applications are due March 22, 2021 at 11:59pm PST.

Please see the “APPLY” tab on the top banner of our website to apply.

Our primary concern is for the safety and health of the entire DIG community, so we will only operate following the guidance of University of Washington and public health officials. We will be monitoring public health guidelines leading up to our 2021 program and update our community accordingly.

2019 DIG Field School participant holding a dinosaur tooth they found

Fossil plant research at the Burke Museum

By: Paige Wilson

Over the past year, the Burke Museum in Seattle has shifted to accommodate new health and safety guidelines to slow the spread of COVID-19. While the Burke’s exhibit spaces have been intermittently closed or with reduced capacity, Burke collections staff are still hard at work and finding creative ways to share their research and curation with the public.

Many of our researchers have also shifted to entirely remote work, bringing microscopes and other tools home to study fossils from the safety of their living rooms! However, sometimes fossil work can only be done in person at the museum. I am a paleobotany graduate student and have been visiting the Burke periodically to take pictures of fossil leaf specimens. My photography setup involves a copy stand with a mounted camera and high-powered lights.

The camera set up at the Burke Museum that I am using to photograph fossil leaves in the collection

I am in the process of photographing thousands of individual fossil specimens—if you have the opportunity to visit the Burke Museum, you may see me snapping photos! Once I have taken all of the photos I need, I can continue my data analyses at home. I am using these digital images to measure leaf characters (e.g., leaf size, tooth size, leaf area) that are known to be related to climatic conditions, such as temperature and precipitation. Because plants are stationary, they must be well adapted to the environmental conditions in which they live. These leaf fossils will help me estimate the paleoclimate conditions during the interval before and after the Cretaceous-Paleogene (K-Pg) mass extinction. My photos will also be uploaded to the Burke’s online specimen database so that the general public and researchers around the world can browse our collections, collaborate, and continue collecting data for research projects. This project is an excellent example of how many researchers, including myself, are adapting our work to more virtual-based formats while continuing necessary in-person research as safely as possible.

An example of an image of a fossil leaf from the Tullock Formation (Hell Creek study area) that was taken by me. I am processing images like this to measure characters that will tell me about paleoclimate in the early Paleogene

A visit to a classroom, virtually

By: Henry Fulghum

I recently had the pleasure of giving a virtual presentation to a high school class. I was invited by one of our high school volunteers, Carlos Lopez Diaz, to lead a guest seminar on paleontology at Highline Big Picture High School. All Big Picture students participate in what are called “Off-site Internships”. That is, throughout the year, students spend two days a week off-site working in internships in fields of interest. As a budding paleontologist, Carlos reached out to us in 2019, and has been an avid fossil sorter in the Wilson Mantilla Lab ever since.

As part of their internships, Big Picture students develop and teach a high school course with the help of an advisor, complete with readings, presentations, and a fully fleshed-out lesson plan. In Carlos’ “Paleontology” elective, he had also planned trips to our lab and the fossil collections at the Burke Museum, but was forced to make some adjustments with the onset of the COVID-19 pandemic. So, for the past semester, Carlos has been leading his “Paleontology” elective virtually. Some of the topics that Carlos worked into his curriculum included dinosaurs of the Morrison Formation, the evolution and reconstruction of Spinosaurus aegypticus, paleobiogeography, and the breakup of Pangaea. This week’s focus was “The Day-to-Day of Paleontology”, and in preparation, Carlos had his peers read articles covering paleontological dig sites, the process of fossil curation, and the importance of science communication. As Carlos’ off-site advisor, I was invited to present at his virtual seminar to cap off the week’s unit. As part of my presentation, I spoke about sediment processing, the Burke museum, the DIG Field School, and my responsibilities as a lab manager – as well as how those responsibilities have changed over the last year.

Going into a virtual classroom, I’m not sure what I expected. However, after months of working from home, I was happily surprised by how meaningful these educational interactions with students could be. Some of my favorite moments came during the Q&A session when I fielded questions like “What does the future of paleontology look like?” and “What advice do you have for students interested in pursuing a future in paleontology?” There was a high level of student enthusiasm and engagement!

Expanding access to science has always been the central goal of the DIG Field School, and perhaps now more than ever, it is crucial that we actively seek to connect and engage with the curious public. If any DIG alumni are interested in having members of the Wilson Mantilla Lab conduct a virtual visit to their classroom, please let us know!

Wilson Mantilla Lab manager and DIG instructor Henry Fulghum pictured in the Wilson Mantilla fossil sorting lab

Microscopic structure of bones provide clues about how ancient mammals grew

By: Luke Weaver (5–10 minute read)

Ever wondered why it takes so much longer for a human to grow up and grow old compared to a dog? Or why elephants are pregnant for 22 months but a mouse is only pregnant for 22 days? Questions like these are a major focus for biologists who study animal life history, the changes an organism goes through from the time it is a developing embryo to the time it dies. Biologists can follow an organism around throughout the course of their life and carefully document all of the changes that occur. But for me, as someone who studies our earliest mammal ancestors that lived alongside the dinosaurs, I want to know when different mammalian life histories evolved and in which ancient mammal groups… and to do that, we need to chop tiny mammal bones to pieces and look at them under a microscope! *insert evil Tim Curry laugh here*

Life history strategies are different among the three major groups of mammals. Monotremes lay eggs and the babies that hatch from them are tiny and poorly developed, growing for a long time outside of the egg. Marsupials give live birth, but their babies are extremely tiny—the young crawl into their mother’s pouch where they suckle and develop for a long time. Placentals also give live birth, but their babies are more well developed compared to monotremes or marsupials. Placental babies spend less time suckling and become independent from their mother more quickly.

Monotremes (like the platypus), marsupials (like kangaroos, koalas), and placentals (most mammals you’d think of, humans, dogs, mice, deer) all have very different life history strategies—they are born and grow up differently. There are ongoing debates about when these different life history strategies evolved, so we need fossils to help answer these questions.

Although these life history differences among the three major groups of modern mammals (Monotremes, Marsupials, and Placentals) are well established, determining when these different strategies evolved and whether one strategy is more “primitive” or “advanced” has remained a topic of major debate in mammal biology research. In very general terms, there are two competing camps: (1) Placentals are advanced, marsupials retain more primitive life history traits vs. (2) Marsupials are advanced, placentals retain more primitive life history traits. (Most everyone agrees that monotremes probably retain the most primitive life history strategy because they still lay eggs). My research is focused on using the fossil record to fill in the gaps between modern marsupials and modern placentals using 66 million year old mammal fossils.

OK, what does this have to do with chopping up bones?

Life history traits—such as how fast an animal grows, it’s reproductive strategy, or how old it was when it died—may not be preserved very well on the outsides of bones, but they actually leave a pretty recognizable mark on the inside. Paleontologists use bone histology, or the study of bone tissues, to infer life history traits of extinct animals. They do this by cutting slices of fossil bones, grinding them down really thin, and looking at the microscopic patterns under a microscope. The microscopic structure of bones is governed (in large part) by how fast an animal grows, and those growth rates change throughout an animal’s life. Bone growth can also pause during times of stress and leave distinct lines, like tree rings, that can give clues about how old the animal was, when it was born, or whether it lived in a harsh environment. When you hear people talking about how old T. rex was, this is how they know!

Sketch of a mammal femur (A) showing where a cut would be made along the shaft of the bone. Once a chunk is cut out, it is ground down until light can pass through (B). We can then look at the microscopic structure of the bone tissue (C), which preserves clues about the animal’s life history.

OK, what does this have to do with chopping up tiny mammal bones?

Most ancient mammals were really small (< 1 kg) and could probably sit in the palm of your hand. Because I am interested in understanding the evolution of mammal life history strategies, and since bone histology is the best way to figure out the life history strategies of extinct mammals, I need to cut up ancient mammal bones, which are really tiny. First I need to understand the “mark” that different life history strategies leave in the bone microstructure of living mammals (in which we can observe and measure their life histories) so that I can interpret the microscopic patterns we see in the bones of extinct small mammals.  Since 2016 I have been cutting up the bones of modern and extinct small mammals and creating bone histology slides. Not all by myself, thank goodness—shout out to DIG Instructors Henry Fulghum and Dr. Megan Whitney! I’ve been working to take detailed measurements from all of our modern mammal slides and compare the patterns I see to the life history variables we already know about the different species.

My desk setup for working from home and doing bone histology research. One perk: I could watch football at the same time!

Much to my delight, we are finding that the life history strategies of modern mammals leave a pretty distinct signature in their bone tissues! Plus, these signatures are different than what we expected with what people have seen in larger animals (such as dinosaurs). We are cautiously optimistic that these differences are meaningful and we think they will shed new light on whether marsupial or placental life history strategies are more advanced. Beyond the specifics of the results, we are now building a new framework for investigating mammal life history evolution. By ground-truthing the histology of modern mammals and integrating them with the fossil data, we are creating a foundation upon which future studies can build.

Publications from DIG instructors!

Paige Wilson, UW graduate student and DIG instructor, along with DIG director Dr. Greg Wilson Mantilla and Dr. Caroline Strömberg publish their study on the floral diversity from a site in eastern Montana! They described Cretaceous plant fossils from the Hell Creek Formation and demonstrated that changes in floras of the western US were roughly occurring at the same time leading up to the Cretaceous-Paleogene mass extinction.

Example of gymnosperm plant fossils from the Hell Creek Formation (Modified from Figure 5 of Wilson et al., 2021)

Check out new research on multituberculates mammals from Egg Mountain—a dinosaur nesting site in western Montana— by graduate student and DIG instructor Luke Weaver and DIG director Dr. Greg Wilson Mantilla along with other colleagues! These fossils show the earliest evidence of mammal social behavior, such as group-nesting and burrowing behavior!

Fossils of Filikomys primaevus (multituberculate mammal) found at the Egg Mountain locality in western Montana (Modified from Extended Data Figure 1 of Weaver et al., 2021)

DIG instructors, Dr. Dave Grossnickle and Luke Weaver, and colleagues publish their study on examining the skeletons of different gliding mammals! They found that the different groups of gliding mammals all evolved longer limbs over time, but differences in the skeleton that contribute to the gliding apparatus are distinct and detectable among the groups.

Evolution of gliding behavior in mammals and their close relatives. Gliding evolved independently in these different mammal groups and there is evidence for gliding behavior in the fossil record as well! Extinct taxa are marked by the daggers. (Figure 1 of Grossnickle et al., 2020)