Happy National Fossil Day 2021!

National Fossil Day poster for 2021 by the National Park Service.

Today is International Fossil Day! 

International Fossil Day  is an initiative by the International Paleontological Association and the National Park Service (National Fossil Day in the U.S.), the idea is to spread the interest in the life of the past and many different organisations and museums around the world host events or activities today. Of course we, the Time Scavengers team, have to participate in this, there can never be too much paleo-related fun! 

We want to celebrate IFD by showing off our team members’ favourite extinct species or individual fossils, some facts about the species or individual and why we picked them as our favourites.

Click here to visit the National Park Service website to learn more about National Fossil Day, and here to visit the International Palaeontological Association to learn more about International Fossil Day!


A fossil cave bear skeleton. Image credit: Wikipedia.

Most of my paleontology lectures during my undergrad took place in small rooms somewhere deep in the side wings of the institute building, on the edge of the paleontological collection/museum that is located within the institute. Whenever me and my friends were waiting for our professors to show up, we would stare and marvel at the exhibited specimens. I vividly remember walking into that area for the first time, it is dominated by a huge, mounted skeleton of an adult cave bear (Ursus spelaeus) and I was completely blown away by the sheer power it radiates. I didn’t care too much about the T. rex skull cast around the corner that most others found so fascinating. From that first day of paleo classes, having my own mounted cave bear skeleton has been on the top of my bucket list. U. spelaeus lived during the Pleistocene across both northern Asia and Europe and went extinct during the Last Glacial Maximum about 24,000 years ago. They are closely related to brown bears (Ursus arctos), the two species have a last common ancestor about 1.2 million years ago. Even though they were huge, powerful bears that were reaching 3.5m (11.5ft) when standing upright, with large teeth and fearsome claws, it’s currently thought that the majority of the western populations were eating an almost exclusively vegetarian diet! Recently, two very well preserved frozen cave bear carcasses have been discovered in two separate areas of thawing permafrost in Russia, an adult and a cub, both with almost all soft tissue present and intact. I’m already excited and looking forward to reading all the new research that will be done on these specimens!


Cast of U. anceps skull. Image credit: Wikipedia.

I worked at the Field Museum of Natural History during the summer of 2015 and that experience was what solidified my interest in paleontology. I worked with my supervisor on Eocene mammals from the western United States and had some of my first experiences doing large scientific outreach events during that summer. Because of that summer I will always have a soft spot for Uintatheres!

Uintatheres (U. anceps) lived during the Eocene in North America and were large browsers. These animals looked similar to rhinos but male U. anceps had six knob-shaped protrusions coming off of their skulls. Part of my experience working with these fossils was reorganizing the collections space that housed the skulls, they are incredibly heavy! I mentioned that U. anceps were browsers, but they also had long canine teeth that resemble the canines of saber tooth cats. These teeth may have been used as a defense mechanism but also may have played a role in how they plucked leaves from plants. While I don’t work on Eocene mammals now, Uintatheres will always be special to me for the role they played in getting me excited about paleontology and scientific outreach!


Whitney next to Asteroceras stellare.

I cannot pick just one fossil to highlight right now, so here are two of my favorites! In 2016, I was studying in England and visited the Natural History Museum in London where I saw an incredible ammonite, Asteroceras stellare. Asteroceras was a large ammonite that lived during the Early Jurassic and whose shell reached nearly three feet in diameter. Asteroceras was a nektonic carnivore who might have fed on fish, crustaceans, and bivalves.

Whitney in front of an ichthyosaur!

My favorite vertebrate fossil is the Ichthyosaur. I loved visiting the Jurassic Coast in England and got to explore Lyme Regis, both the birthplace of Mary Anning and a town that had references to paleontology everywhere you looked. You can see ichthyosaur fossils in both the Lyme Regis Museum and the Natural History Museum in London and at the NHM, you can see some of the specimens that Mary Anning and her family had collected along the Jurassic Coast. Ichthyosaurs (Greek for “fish lizard”), are marine reptiles that lived during much of the Mesozoic and were thought to be one of the top aquatic predators of their time.


Mike in front of an American mastodon statue!

I have three favorite extinct species: the American mastodon (Mammut americanum), the dinosaur Parasaurolophus, and the chalicothere Moropus elatus. Mastodons are distant relatives of the elephants, and they seem to be overshadowed by the wooly mammoth. However, both lived in North America until the end of the Pleistocene epoch. I’ve always thought that Parasaurolophus was an elegant duck-billed dinosaur, and I’ve seen them featured in several movies in the Jurassic Park series. I think that chalicotheres are so bizarre! Distant relatives to horses, rhinos, and tapirs, imagine a big draft horse with giant claws instead of hooves! I’ve seen several skeletons of these over the years. Moropus elatus went extinct in the Miocene epoch.

Mike next to a Moropus elatus skeleton!
A statue of Parasaurolophus.


Like anyone in paleo would tell you I can’t pick one particular fossil organism as my favorite. Currently my favorite fossil organism is the “bear-dog” known as Amphicyon ingens which would have been a formidable predator during the Mid-Miocene. The cenozoic was a time for innovation in mammals and bear-dogs were the best of both worlds. All the stoic grandeur of a bear and all the cute charm of a dog, what more could you want? The picture shown was taken at the American Museum of Natural History in New York City.


Jonathan Jordan (Paleo Policy Podcast)

For me, the Mesozoic reigns supreme. However, my recent trip to the La Brea Tar Pits in Los Angeles gave me a greater appreciation for the Cenozoic era and mammalian evolution in general. While it may not be my favorite fossil ever, I was captivated by Panthera atrox’s look and the idea of an American Serengeti 340,000 to 11,000 years ago. Genetic analysis suggests with high likelihood that Panthera atrox is a close relative of the Eurasian Cave Lion (Panthera spelaea). After the Bering Strait land bridge was submerged by rising sea levels, Panthera atrox was isolated from its Eurasian relatives and became a distinct species that has been found as north as Alaska and as south as Mexico. Neat! Check out an image of Panthera atrox’s skull on the Smithsonian Learning Lab site!


I’m fortunate to have worked on many different types of animals during my career, starting with dinosaurs, then moving to Devonian brachiopods and their encrusting organisms, and now working on much younger Pleistocene-aged animals that are still alive today. I mostly study biotic interactions, such as predation, so I thought I would share my favourite trace fossil (ichnotaxon), Caedichnus! Trace fossils are different than a body fossil because they show evidence (or traces) of an organism or its behaviour. In the case of Caedichnus, this trace fossil is created by a crab trying to break into the shell of a snail by peeling away at the shell opening (aperture) until it can reach the snail’s soft body. Imagine having a crab try to peel your shell back like an orange – scary! Caedichnus traces are useful for determining how many crabs were in an area, and identifying patterns of crab predation through space and time. I’m now using them to determine the impacts of climate change and human activity on crab fisheries since pre-human times.


Like most of my colleagues above, it is incredibly hard for me to say which fossil is my favorite! So instead, I’ll talk about my favorite fossil group, the foraminifera. Foraminifera are single-celled protists that live in the surface ocean (planktic foraminifera) or in/on ocean sediments (benthic foraminifera). Planktic foraminifera are my favorites; they evolved about 175 million years ago, and still live in the global ocean today! One of the ways which we know about past climate states how the ocean behaved to such warming and cooling events of the geologic past is through analyzing the chemistry of fossil foraminifera shells, or tests! Foraminifera are also incredibly useful in studies of evolution, as they have a robust fossil record. Learn more about Foraminifera here!

Various planktic (surface-dwelling) foraminifera (marine plankton) species. Images are 60-100x.

What’s YOUR favourite extinct species? Let us know in the comments, maybe we will feature them in a future post!

Fossil hunting—On Mars!

Did you see this in the news? NASA is starting a new Mars mission, and this one has a very exciting goal: to find evidence of past life! And to study the habitability of Mars for past life and for humans in the future. 

A new rover, called Mars 2020 until a name is selected (update: Mars Perseverance Rover), will be sent to Mars this summer, with an arrival on Mars February 18, 2021. The rover will explore the Jezero crater for about one Martian year, equal to 687 Earth days. Jezero crater was chosen for study because there is evidence that this crater once contained a lake. 

Elevation map of Jezero Crater. Dark blue and purple are deeper areas, yellow is the highest. The circled area is the area of the mission. NASA/JPL-Caltech/MSSS/JHU-APL/ESA. https://photojournal.jpl.nasa.gov/catalog/PIA23511

Two rivers, on the left side of the picture, flowed into a crater. A flood like broke through the crater wall and allowed water to drain out of the crater (upper right). Inside of the crater is a former delta formed as sediments were deposited as the rivers entered the lakes and deposited sediment.  

Artist’s concept of the delta formed within the ancient lake. NASA/JPL-Caltech/University of Arizona, https://photojournal.jpl.nasa.gov/catalog/PIA22907

Spectral analyses of the deltas and fans have revealed the presence of carbonates and hydrated silicas.

Spectral analyses of the detlas and fans have revealed the presence of carbonates and hydrated silicas.

Carbonate is a chemical composed of carbon, oxygen, and a metal or hydrogen. For example, chalk, seashells, and egg shells are all made of calcium carbonate crystals (CaCO3). Carbonates need liquid water and an atmosphere with carbon dioxide to form. On Earth, carbonate rocks may be formed by the accumulation of tiny fossil shells, but carbonates can form abiotically (without life). Limestone, a carbonate rock, is a good preserver of body fossils and trace fossils. Silica, a combination of silicon and oxygen, forms in water. Chert and flint are examples of silica rocks. Chert is also formed by the accumulation of tiny shells, but these are made from silica, not carbonate.

Any fossils that are left on Mars from its warmer, wetter periods would likely be found in carbonate and silica deposits. Scientists expect that these fossils would be microorganisms (single celled organisms). 

In addition to searching for fossils, Mars 2020, Perseverance will also: 

  • Determine past climates that may have allowed ancient life to exist
  • Study the geology of Mars, including the processes that affected and altered Mars’s surface, as well as looking for rocks that formed in water and what they might reveal about past life
  • Help prepare for human explorers by studying radiation levels on Mars’s surface and chemicals common in martian soil that are known to be harmful to humans. 

This may be a very exciting mission, but the wait will be long! The search for fossils will be the last part of the mission. But we’ll keep you posted!

For more information, visit NASA’s about this mission: Mars 2020 Mission and Mars Perseverance Rover.

Big Bone Lick State Historic Site

Mike here –

I recently visited Big Bone Lick State Historic Site (Union, Kentucky) on the way back to Ohio from a weekend in Kentucky. I’ve been meaning to visit this place for years, so I’m glad I finally had a chance to do so! Big Bone Lick is an important site for paleontology, archaeology, and US history.

Big Bone Lick SP is the site of a salt lick, or area where animals come to obtain salt and other minerals by licking the soil for salt crystals. Natural salt and sulfur springs are the source of the minerals at Big Bone Lick, and they attracted animals from all over.

In historical times, white-tailed deer and North American bison visited the lick, but much larger mammals came during the Pleistocene epoch (2.5 million to 12,000 years ago), also called the “Ice Age.” The remains of extinct mastodons, mammoths, North American horses, ground sloths, and tapirs have been found here, as well as the still living bison, musk oxen, and peccaries. Some of them became stuck in mud and died, and their preserved skeletons became the source of the “big bones!”

Diorama of a modern bison taxidermy with ancient neighbors.

Paleoindians hunted the megafauna at Big Bone Lick, and left behind their tools at the site. Native Americans continued to hunt here into colonial times, and told the Europeans about the big bones found in the soil. President Jefferson ordered Merriweather Lewis and William Clark to stop here on their expedition to investigate these reports. Specimens were excavated and eventually sent to France for analysis by Georges Cuvier, an anatomist credited with developing the concept of extinction. He compared the remains of Asian Elephants, African elephants, and the “elephants” found at Big Bone Lick and determined that these remains came a type of elephant that no longer lived. He named this animal Mastodon, but these fossils had already been described under the name Mammut. The study of these remains has given this site credit for the birth place of vertebrate paleontology in the United States.

The visitor’s center is on Mastodon Trail!

Long after the bison were extirpated (no longer present in their native habitat, but not extinct) from Kentucky, Kentuckians mined salt and opened a health resort, at which people bathed in the mineral-rich water. 

I have always loved the Pleistocene megafauna, and I make a point to see these fossils whenever I can. Mastodons are tied with Moropus (a distant relative of horses and rhinos, imagine a draft horse with claws!) as my favorite fossil animal, and get so excited seeing them! 

The visitor’s center has nice displays about the megafauna found at Big Bone Lick, including fossil material and reconstructions of what they may have looked like. There is information about the Paleoindians that inhabited this region and their tools. Historical information about Lewis and Clark is also included in the displays. 

A mounted giant ground sloth skeleton, and a display comparing mastodons and mammoths.

Behind the visitor’s center are life-size statues that represent iconic Pleistocene megafauna. Many of them are“trapped” in the sediment, and are on their way to become fossils. This was the perfect opportunity for a selfie with a mastodon!

A trapped mammoth and a dying bison.
My selfie with a mastodon!
A giant ground sloth.

The site is actually quite large, and features a campground and several hiking trails. I took one of these trails to see the salt/sulfur springs. I could smell the sulfur as soon as I reached this point in the trail. It was pretty awful, and it amazes me that people came to bathe in these waters for the “medicinal properties” centuries ago. 

A salt/sulfur spring with salt crystals.

I continued along a trail which follows Big Bone Creek. Fossils and artifacts are still exposed as the sediment washes away, and modern excavations occur when fossils are found on site.

These signs are all over the site.


Big Bone Lick Creek. Fossils are still exposed as the sediment is washed away through erosion.

Informational signs are included along the trails about the history of the site and about the animals that once lived in this region. 

The park maintains a small herd of American bison (Bison bison) on its grounds. The animals are rotated around their paddock to allow the plants time to recover from grazing and trampling. Unfortunately for me, they were located too far away for me to see with them with my limited time. It is hoped that the ecosystem will be restored to its condition before the bison were extirpated from this area. 

There be bison. Somewhere…

I had a great visit to Big Bone Lick State Historic Site! If you enjoy ice age megafauna, and are in or near Kentucky, consider stopping by! For more information, visit Big Bone Lick State Historical Site

Fossil Collecting at Caesar’s Creek Spillway

Mike here –

The Caesar Creek Lake Visitor Center

When the students were on spring break a few weeks ago, I decided to take a few days off to go fossil collecting. The first site I went to was the spillway for the reservoir in Caesar Creek State Park. This is a special place for me: it’s the first site we went to collect fossils from during my paleontology course when I was a junior in college. I’ve been going back to this site for about 14 years, but I hadn’t been since 2013, when Jen, Adriane, our friend Wes, and I all went on a long weekend. During this time, Adriane and Jen were helping Alycia Stigall build the Ordovician Atlas. If you are interested in learning more about the organisms found, rock outcrops, and more head to that website!

Jen, Mike, and Adriane out collecting in the spillway in 2013. Wesley is taking the photo. An excellent weekend trip.

This site is exposed Ordovician limestone and shales (click here to learn more about types of rocks), representing warm, shallow marine environments. Three rock formations are exposed: Waynesville, Liberty, and Whitewater. If you are interested in learning more about rock formations, click this link which will go into detail on formations! Because collecting is restricted to the base of the spillway, all of the rocks are mixed together and it is difficult to tell which formation the specimens come from. When collecting from Caesar Creek, one must obtain a pass from the Visitor’s Center—run by the Army Corps of Engineers—and agree to follow their rules. Probably the most frustrating rule is that one can’t use tools to extract specimens, not even another rock! But, regardless of these rules, this location is safe for individuals and families to come collect.

The walls of the spillway. Filled with fossils!

I was excited to see what would be exposed in the spillway. This was the first warm weekend of the year, and it had rained the day before. I figured fossils would have washed out from the wall and would not be picked over yet. Usually after a good rain you get lots of new fossils coming out of the rock due to the increased erosion of the outcrop. So it may be wet and gloomy but good for fossil collecting! It sure paid off because today was one of the best fossil collecting I’ve ever had at Caesar Creek!

Crinoid calyx. Sadly, I could not extract this!
Cephalopod shell cast in the rock.
Brachiopods, bryozoans, and fragments of Isotelus.

This was the best haul I’ve had from Caesar Creek in a long time. I was not able to collect many of the really cool specimens I found. They were either way too big and/or stuck in a rock and I couldn’t use tools to remove them. I’m glad I got to see so many amazing specimens and take some home!

Read more about the Caesar’s Creek Spillway on the Dry Dredgers site by clicking here or the FossilGuy’s site by clicking here.

A huge burrow!
Trace fossil slab!
Fossil assemblage
Slab of trace fossils!


Fossil assemblage
Bryozoan and other shellies.
I found this fragment of an Isotelus, which is the largest fragment I’ve ever found. I believe this is the posterior end.
Clockwise from top: Flexicalymene trilobite, cephalopod, and various gastropod species.

Urban Fossil Hunting

Mike and Jen here –

Figure 1

I couldn’t believe what I was seeing. I was on a tour of campus for my paleontology course, and Dr. Sandy took us to a low retaining wall in front of the Science Center. There it was: a large Pentamerus brachiopod (Fig 1). I’d walked by this wall for years and never noticed it before! During the rest of the tour, I saw fossils all over campus, and I had never even thought to look for them in the building materials.

Ever since then, I’ve taken closer looks at the stones used in buildings to see if there are fossils. You should, too! But ignore the igneous rocks and marble, just go for the limestone, dolostone, and sandstone pieces. The fossils I’ve seen include trace fossils and body fossils. Trace fossils are fossilized behavior of an organism, whereas body fossils are the actual skeletal or imprint of remains.

Figure 2

Primarily, I’ve encountered trace fossils. The Dayton Limestone, a formation found near Dayton, Ohio, is Silurian-aged (443.8-419.2 million years ago) limestone that was used for building foundations all over the state. It is full of burrows that are highlighted by a lining of hematite (Fig 2). The hematite likely came into the burrows after the organisms were done occupying them. This mineral helps the burrows stand out in the rock. The foundation on the left is a building on the campus of the University of Dayton. The founding on the right is a building in downtown Springfield.

Figure 3
Figure 4

Further exploration for urban fossils led me to find trails on the base of a lamppost outside of one of the courthouses in Springfield (Fig 3). I forgot a scale for this picture, but these trails were about 10 cm in length. I found this next burrow (Fig 4) in one of the retaining walls outside of the library at UD. See what I mean about fossils in places you wouldn’t expect them?

Marine animal body fossils are quite easy to find in building materials. I found these Silurian fossils in a retaining wall near some of the older buildings on UD’s campus. Large brachiopods and gastropods may be found in these stones (Fig 5), as well as colonial corals and horn corals (Fig 6). Sometimes it is difficult to recognize the fossils because the animal is within the rock and you are only getting a two-dimensional view of what it looks like.

Figure 5
Figure 6
Figure 7

Sometimes, the fossils can be very small and hard to pick out from the rock they are in. I walked by this wall for nearly 15 years and never noticed all of the gastropods, bryozoans, and crinoids until just a few weeks ago (Fig 7)! Another example of small fossils was found by Jen when she went to the Biltmore Estate in Asheville, North Carolina. She was chatting with her family when she looked down and recognized the rock, it was filled with small gastropods and bryozoans that she knew to be Mississippian (360-325 million years ago) in age (Fig 8).

Figure 8

Be sure to be on the lookout inside of buildings, too! Many building stones are made of fossiliferous rocks and they are quite visually appealing so they end up as table tops, counters, and even bathroom stalls! Jen saw this table, made of polished fossiliferous limestone, inside of the Biltmore house (Fig 9). I found these ammonites in the flooring at the Ohio Statehouse (Fig 10). Each side of the tile was about 2 ft in diameter.

Figure 9
Figure 10

Where Jen lived in Eastern Tennessee, the common limestone is called the Holston Limestone. This is the ‘marble’ that gave Knoxville the name of Marble City. Marble is a metamorphic rock whereas limestone is a sedimentary rock. Sometimes limestone can have really small grains that makes it look like marble. As a local rock it is used all over the city in a variety of places. It decorates the exterior of buildings downtown (Fig 11) and is even sculpted into monuments of past events (Fig 12).

Figure 11
Figure 12

Maggie and Jen went on a recent research trip to Oklahoma and noticed something interesting about their window sill in the kitchen (Fig 13). It was a nice pink color with lots of white specks. It happened to be the Holston Limestone from where they both were living in Eastern Tennessee! This rock has very specific features that allow you to identify it wherever you may be. Jen even discovered this rock in an old hotel (now a university) in St. Augustine, Florida.

These just a few examples of the fossils that we have seen used in construction and design. As you walk around city buildings, be on the lookout for limestone blocks, especially on older buildings. There may be a few fossils hiding in plain sight!

Figure 13

Ancient hydrothermal seafloor deposits on Mars

Ancient hydrothermal seafloor deposits in Eridania basin on Mars
Joseph R. Michalksi, Eldar Z. Noe Deobrea, Paul B. Niles, and Javier Cuadros
Summarized by Mike Hils

What data was used? High resolution imaging and spectroscopy data about mineralogy and geology

Methods: Used data from instruments on the Mars Reconnaissance Orbiter, a satellite currently orbiting Mars:

    HiRISE (High Resolution Imaging Science Experiment) was used to define the ancient basin boundaries and to inspect the types of features and rocks located in the Eridania basin. HiRISE is a camera onboard the Mars Reconnaissance Orbiter than can resolve objects to about a foot long on the surface of Mars.

    CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) to study the minerals and rocks found in the Eridania Basin. Materials bounce light off of them in a consistent pattern and energy, and spectrometers can analyze that light and identify the material on Mars’ surface.

Results: The Eridania Basin was probably up to 1.5 km (0.9 mi) deep, and flowed into a canyon named Ma’adim Vallis. Images from HiRISE show that the western half of the basin consists of massive stone that lacks bedding planes and has eroded into buttes and mesas. The basin would have held about as much water the Caspian Sea on Earth currently does. This basin is shaped different than many of the other Martian basins, and it is thought that a covering of ice kept sediment from settling on the bottom. A comparison of the craters in this part of the basin suggest that these rocks are about 3.77 Ga (G = giga, SI prefix for billion, a = annum, Latin for year) old.

Analysis from CRISM found evidence of minerals and rocks associated with deep ocean water on Earth, including iron and magnesium rich clays, serpentinite, carbonates, and chlorides. For example, serpentinite, a metamorphic rock that looks like green marble, forms when basalt reacts with warm, deep sea water. Carbonate minerals are common on Earth in the form of limestone, marble, seashells, and corals. The authors suspect that the carbonate formed due to hydrothermal interactions. Chlorides, such as salt (sodium chloride), form on Earth when water evaporates.

Map of the Martian terrane with colors indicating highs (orange) and lows (blue) of an ancient sea. The data points in the legend are minerals that were identified at each location.

Why is this study important? This study is important in two ways. First, one idea for the origin of life on Earth is that it developed around hydrothermal vents in the ocean. Although ancient rocks have been found suggesting such environments in the past, they have been significantly altered by weathering and metamorphism, and vital information has been lost. Martian sites, which haven’t been altered nearly as much as Terrestrial ones, might be a good proxy for understanding early environments on Earth. Secondly, the identification of such sites on Mars could provide key places to look for signs of life on Mars.

The big picture: Understanding how life began is a huge problem that scientists in many fields are exploring. Life may have evolved on Earth, or it may have arrived here from some other body. The identification of hydrothermal environments on Mars would allow scientists to gain a better understanding of hydrothermal environments on Earth as life was evolving and try to see if life could have started here. This would also allow astrobiologists to look for evidence of extraterrestrial life on Mars.
Two other bodies in our solar system may harbor life around hydrothermal vents. Jupiter’s moon Europa and Saturn’s moon Enceladus are both covered in salty water capped with ice, and both experience tectonic activity due to the gravitational pull from their host planets. In addition, organic molecules (chemicals made mostly of carbon that are often associated with organisms) have been detected in water escaping from Enceladus. If life could have evolved in hydrothermal environments on Earth and Mars, it is likely Europa and Enceladus both host extraterrestrial life now.

Citation: Michalski, J., Dobrea, E., Niles, P., Cuadros, J. 2017. Ancient hydrothermal seafloor deposits in Eridania basin on Mars. Nature Communications, 8:15978. doi: 10.1038/ncomms15978

J. Mike Hils, Paleontologist and Instructor

Visiting with a metallic Tyrannosaurus rex.

“Let me get this straight: You are a Biology major that takes Geology classes, and you work for Chemistry?” A friend said that to me many years ago. It seemed funny back then, but it still true. I have always loved the natural sciences, and my experiences as a student and as a college instructor have allowed me to participate in these three fields.

My research involved studying the relationships between sediment types, burrowing animals, and the burrows shapes that they make. Although this may like a strange topic, consider this: Insects and mammals can’t burrow into groundwater (water stored in sediment underground), so their burrows stop at the water table (the boundary between dry soil and water-soaked soil). Many plants cannot live if their roots are submerged, so the roots also stop growing at the water table. Because roots and burrows can be preserved in the fossil record, they can be used to determine past climate conditions. For example, if a paleontologist finds that roots and burrows found in a rock layer all have the same depth, then there was groundwater in the past. In addition, the paleontologist could determine that 1) there was enough precipitation to allow water to soak into the ground, 2) there is enough accessible water for an ecosystem to live, and 3) there may have been a river or lake nearby as the water table is near the soil surface.

Burrows, tracks, trails, and root casts are called trace fossils. Trace fossils can also be used to determine what organisms were present in an ancient ecosystem, how diverse the organisms were, and what environmental conditions were. Much of this work is done by studying actual burrows produced in the field and in the laboratory. My work involved allowing trapdoor spiders, wolf spiders, and tarantulas to produce burrows in the lab. After moving the spiders into a new habitat, I poured plaster into the burrows and measured the dried casts.

This is an example of a cast of a burrow created by the tarantula pictured.

One of the big goals of our lab group is to determine the relationship between burrow-shape and burrow-maker. Several arachnid species have been studied in this lab: scorpions, whip scorpions, and spiders. We have found that although these groups are closely related, they all produce very different burrow shapes, and that shapes appear to be related to the behavior of the species as well as its body shape. My favorite part about being a scientist is seeing something that may be mundane and knowing there is a complex story behind it. For example, a piece of limestone used to line a flower bed represents a past environment, the skeletons of small organisms, and the transport of chemical elements from the continents to the oceans.

For the past few years, I have focused more on teaching than on research. I have been lucky enough to teach at three universities in both chemistry and geology. I have worked with many kinds of students, both science and non-science majors. Much like Time Scavengers is addressing, I have found that many of my students have very little interest in science or think that they can’t understand it. In my classroom, I encourage students to find relationships between the material and their daily lives. Although I have enjoyed my research programs and am proud of my work, I have decided that education is my real strength. I am starting a licensure program this fall to earn my teaching licensure for high school earth science and life science. I hope that my research experience and multidisciplinary approach will encourage all of my students to appreciate the natural world and never stop learning about it.

For people wanting to become scientists, I want to offer two pieces of advice: 1) All of the sciences intersect in some way, so don’t despair if you have to study one you hate to get to the one you love, and 2) The more experiences you have, the better prepared you will be for a career or in graduate school. Find ways to become involved in research or outreach. Apply for internships, even if they don’t pay!

Mike helped lay the ground work for developing a website on their lab’s ichnology projects called the Continental Neoichnological Database. Click here to learn more about the database.