Diving into the Ordovician Sea

Maggie here-

My workstation while I was in Iowa at the Paleontology Repository. I spent a lot of time using a microscope to look at specimens and typing notes about each one on my computer. Color coded spreadsheets are my favorite way to organize all of this information!

I just got back from a whirlwind trip to the University of Iowa to do research in their paleontology repository. This collection is very interesting because it is a massive fossil collection that is actually housed in a geology department rather than a museum. That might seem weird to you, but it was a really nice environment to do research in. Their collections manager, Tiffany, has a small army of undergraduate students that are working with her to help maintain the collections, so the repository has a really nice homey feel to it. Museum work can be a little lonely at times (often you are the only person working in a small room surrounded by fossils), so having Tiffany and her undergrads pop in from time to time to chat was a nice break from research.

Picture of the paracrinoid Canadocystis tennesseensis. This is the mouth of the animal that has a strange S shape to it. Most paracrinoids look very different from one another (even their mouths are different!) but we can still get a lot of information about them and how they relate to one another by looking at their shapes and different characteristics.

So, just what do paleontologists do when they go to a museum to do research? Well, the simple answer is: we look at fossils. For any project that we are working on, seeing as many individual fossils of the same species or even same group gives us a better idea of what is “normal” for that organism. Your research question(s) will determine what in particular you are looking for or paying attention to on each fossil. So for my group that I’m working on, paracrinoids, I’m paying a lot of attention to details around the mouth, differences in plate shape (the plates that make up the body of the animal), and if there is any organization to their plating. This involves a lot of close up work with a microscope to look at these features and careful note taking about what I’m seeing. The data that I collect at museums has to be detailed so that when I get back to my university I can recall specimens and use that data in my analyses. Sometimes if we are lucky, we get to take some specimens back to our universities to keep working on them, but more often we just have our notes and photos to go off of. So our time and work at the museums is invaluable!

Image of the Repository in Iowa-all of these cabinets are full of different fossils from different places. This is the part of museums that most people never see, but so much of a collection is stored behind the scenes waiting for researchers to come look at them!

Research weeks at museums are really long, but the time flies by! You are hyper-focused on your research and your fossils. Even when you are not at the museum working, you are in your hotel catching up on the work that you are missing at home. Between looking at the specimens, taking notes, taking pictures, and trying to find patterns in what you are looking at, the days just fly by. But, I always like to save a little time for myself to wander around the exhibits and look at other specimens in the collection because you are surrounded by wonderful fossils! But for as long and hard as a week researching at a museum can be, the trips are always fun and you come away having learned a lot!

How Did Horses Get to Just One Toe?

Mechanics of evolutionary digit reduction in fossil horses (Equidae) *
Brianna K. McHorse, Andrew A. Biewener, Stephanie E. Pierce
Summarized by Time Scavengers contributor, Maggie Limbeck

What data were used? This study used metapodials (toe bones) from 12 fossil horse genera as well as from a tapir (herbivorous mammal that looks similar to a pig, but that also has an odd number of toes) to collect data. The metapodials were imaged in cross sectional views to determine load strength (how was weight distributed among the main three toes of fossil horses and the one toe of recent horses) and geometry of the metapodials.

Methods: The metapodials from the fossil horses and tapir were micro-CT scanned (3D x-ray scanning, like the human procedure but on a smaller scale) and the images were manipulated to see the cross sectional area and other views using the open source program ImageJ with the plugin BoneJ. The images were then measured and corrected for evolutionary changes using the open source statistical software, R. Estimates for bone stress were calculated using a toe reduction index (TRI), reconstructed body weights, and angle of metapodial during ground reaction at two speeds of forward locomotion. Additionally, the amount of stress that the metapodials could support was estimated using beam mechanics (an engineering process that looks at how much stress a hypothetical beam could withstand before bending and/or breaking).

Results: Looking at the geometry of the metapodials, it was determined that as the fossil horses grew in both size and weight, their need for four front and three back toes was decreased, and as such the digits gradually decreased to one on all four limbs. For the stress experiments, as the fossils moved forward in time to recent horses, it is seen that the amount of stress that can be placed on metapodial III (what we see expressed as the hoof) increases through time and the dependence on the two metapodials on either side of digit III decreases. This statement is true for both front and back metapodials at both a moderate speed (trotting) and performance (acceleration, jumping).

Figure 1. Image of the toe reduction index (TRI) shown across a phylogenetic tree (evolutionary tree) with the cross sectional view of the metapodial being analyzed. Based on the TRI it is apparent that there is a gradient for toe loss and that there is only one genus of horse, Equus, that truly has one toe. You can also see that for those early horses that still had side toes that the shape of the toe in cross section has a much different shape and therefore still needs side toes to some extent.

Why is this study important? This study is important because it supports two hypotheses that were held about digit reduction in horses. That a) the increased body mass of horses selected for a single, strong metapodial and b) that as horses grew taller, the cost of speed from the side toes outweighed their use in stabilization. This also contradicts the commonly held belief that horses experienced digit reduction as an adaptation to the replacement of forests by grasslands.

The big picture: The big picture here is sort of two-fold. Digit reduction in tetrapods (four-legged creatures) has been of interest to many scientists because as tetrapods emerged onto land 5, 8, even more digits was the ancestral state for these organisms. As we see today, that is not the case. The vast majority of the organisms that we think of have 5 or less digits on their hands and feet, so we want to understand what drove the process of digit reduction in every animal. Second, this study highlights that it is important to keep testing hypotheses even if they have been held for a while. The additional lines of evidence provided by this study give more credibility to two commonly held hypotheses while continuing to falsify the common explanation for digit reduction in horses.

Citation: McHorse BK, Biewener AA, Pierce SE. 2017. Mechanics of evolutionary digit
reduction in fossil horses (Equidae)
. Proceedings of the Royal Society B 284: 20171174.

*all samples in this study were fossils, no live animals were used

Women in STEAM Panel Discussion

Jen & Maggie here –

There was a statewide STEAM (science, technology, engineering, arts, and mathematics) festival that occurred at the end of October. Last spring, Maggie and I started to plan how we could contribute to this festival. We wanted to host something targeting young students and get them excited about continuing their education in the STEAM fields. We teamed up with the McClung Museum of Natural History and Culture to host a “Women in STEAM Panel Discussion“.

We spent a considerable amount of time searching for panelists but eventually ended up with a planetary geoscientist, paleobiologist, robotics engineer, industrial engineer, and biochemist! The career stage of these women all varied, an aspect I found to be key on this panel. I was the paleobiologist on the panel and Maggie was our fearless moderator. Prior to the panel we created trading cards for each of the panelists with an image, their name, and title on the front and the back had a short biography and what facets of STEAM their work represents.

Example of the trading cards created for the STEAM panel discssuion.

We wanted to showcase the diversity of projects and fields that really tie into STEAM. As a paleobiologist, I spend much of my time looking at rocks and fossils but I also spend an immense amount of time creating complex 3-dimensional models to get more information on extinct animals. Without some artistic creativity and innovation, these models would be difficult to assemble.

The panel discussion began with a 3-5 minute brief history introduction about how we got to where we are today. A main goal of this panel was to showcase how different everyone’s journeys are, there is not one specific way to achieve your goals but usually it’s messy and a bit challenging. After the introductions, Maggie led us through some questions that we had already came up with to help move the panel along. We covered questions such as “do you still learn new things?” to “what can current STEAM students do if they feel they are not succeeding?”

We opened the floor up for questions as well and had a very productive discussion. Topics from the audience ranged from challenges faced as a women in our career positions to consciousness in robots. Events like this are not only beneficial to the audience but also to the panelists! Maggie and I both had a wonderful time and learned a lot about some very successful women and left feeling very empowered.

Click here for an article about the event from the Daily Beacon.

The Dinosaur that Went Viral: Looking at the science behind the Facebook posts

An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics

Caleb M. Brown, Donald M. Henderson, Jakob Vinther, Ian Fletcher, Ainara Sistiaga, Jorsua Herrera, Roger E. Summons

Summarized by Time Scavengers contributor, Maggie Limbeck

What data were used? The holotype specimen (fossil or other specimen that all others are compared to to determine what it is) of Borealopelta markmitchelli was used for all experiments touched on in this article. Data was also collected from other members of the Ankylosauria (armored, herbivorous dinosaurs with a club on their tail) clade for comparison.

Methods: A phylogenetic analysis (family tree) was completed using this new dino as well as others from the Ankylosauria and Nodosauridae (Ankylosaurs missing the club on their tail) clades to determine where in the dinosaur tree B. markmitchelli belongs. This also provided data for comparison in life habit and some of the unusual features of this particular dinosaur. Additionally, geochemical studies were done on this specimen, including scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Both of these methods were used to get an idea of what the preserved organic material on the specimen was and determine what kinds of fossil melanins (pigments) were present.

Results: The resulting phylogenetic tree from this study does place B. markmitchelli where one would expect it to go within the Ankylosauria tree (within the Nodosauridae clade). The TOF-SIMS experiment showed that there were ions present that indicate benzothiazole and therefore pheomelanin was present. These particular chemicals would indicate that parts of this dinosaur were reddish-brown in color. However, not all parts of the osteoderm (bony skin) and epidermal coverings (scales) show this reddish-brown coloration.

Figure 1. A graphical summary of the paper. We see an image of B. markmitchelli that is exceptionally preserved, the results of the mass spectroscopy experiments that told us that there is countershading (camouflage) caused by the pigment pheomelanin that gave the dinosaur a reddish brown color. This reddish-brown color is a result of strong predation pressure and an attempt to better camouflage themselves.

Why is this study important? This study is important because it highlights how much we can learn from one extremely well preserved individual fossil. It was used in a phylogenetic analysis to determine where it belongs in the dinosaur-scheme of things, images were taken of the skull, and geochemical data was returned to determine the coloration of the skin. From these studies the scientists were able to determine that these dinosaurs used camouflage to help protect them from predators. This is very different from what we see today in predator-prey interactions. Borealopelta markmitchelli was by no means a small dinosaur (~5.5m long and ~1,300kg) and had significant body armor yet it still needed camouflage. Today, large mammals comparable to this size do not need camouflage because even the fiercest predator does not go after grown adults. This new relationship between Cretaceous predator and prey highlights major differences in large predator-prey interactions through time. This specimen will continue to play a major role in research for years to come.

The big picture: There are really two big picture things to take away from this article. The first being that science, and ground breaking science in particular, is always interdisciplinary. These paleontologists relied on geology, biology, ecology, and chemistry (to name a few) to come to their conclusions about B. markmitchelli. This is really important because people always think that science is very isolating and you only work on your own, when in actuality science is accomplished by a team of people who can support you and fill in knowledge gaps. Second, it is important to look into those flashy science articles that pop up on your newfeeds and on Twitter. Those articles are press releases to get you interested in the science that is being done on these fossils or rocks or bacteria. We scientists get excited about our work and want to share it with people-take the time to do so, get excited about nature, and keep reading!

Citation: Brown et al., An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics, Current Biology (2017), DOI: 10.1016/j.cub.2017.06.071

Field Camp in Scotland

Maggie here –

I recently returned from a five-week field camp in Scotland. Field camp is a course that most geologists participate in that is intended to teach students how to collect geologic measurements in the field, recognize geologic structures like folds and faults, understand age relationships of the rock, and ultimately make sense of all of this by making maps and cross sections (interpretations of what the surface geology looks like underground). Field camps are incredibly important as geology students because it reinforces the ideas that the best geologists are those that have seen the most rocks and that geology needs to be learned outside, not just in the classroom.

Figure 1. Geologic map of Scotland. From the key you can see that Scotland has a lot of different rock types that represent much of the time in Earth’s history. The dashed yellow lines that have been drawn in follow the path of two major faults in Scotland; the Great Glen Fault to the North and the Highland Boundary Fault to the south.
So, why Scotland for field camp? Scotland is an interesting location geologically, because for much of Earth’s history it was essentially a ping pong ball with sections of the country getting added on by collisions with other continents as it bounced around. If you look at a map of Scotland you can see two almost parallel lines dividing the country into three pieces (Figure 1). The top most fault is the Great Glen Fault which runs through the city of Inverness and Loch Ness (where the Loch Ness monster resides). The fault further to the south is the Highland Boundary Fault which does divide the country into the Highlands and Lowlands. Each of these pieces was accreted (added on) during a different collisional event. Surprisingly, the last, and youngest, collisional event that happened, when Baltica (Northwestern Europe) collided with Laurentia (North America, Greenland, Scotland), deposited the oldest rocks that you can see in Scotland. These rocks are ~3.2 billion years old and they lay on top of limestone that is ~540 million years old (Figure 2). Seeing this age relationship in the field tells us that something crazy was happening geologically!

Field camp is a lot like summer camp mixed with a typical college class-there is a lot of fun to be had with fellow rock nerds, but also a lot of learning and homework to be done. On a typical day we would leave our hostel or house by 8:30am, work in the field, mapping and collecting data, (either in small groups or individually), leave the field around 5pm, go home and cook dinner for your small group, then work on interpretations of our data and prettying up our maps. Usually at the end of the week we would have a larger project to hand in based on the maps that we had made that week and our interpretations of the area (Figure 3).

Going to field camp can seem daunting at first, especially if you are going on one outside of your home country, but truly is an important experience in learning to be a geologist. Like practicing a sport or instrument, you have to practice geology skills in order for them to become second nature and field camp is the best place for that practice. For a lot of people, this is where geologists have their first “I am a geologist” moment. So, for anyone who wants to be a geologist (or paleontologist or other earth scientist) get outside and look at some rocks and fossils and start observing, because the best geologist has seen the most rocks!

Figure 2. “The Sandwich” roadstop. In this image the red dashed lines represent two thrust faults from the Moine Thrust in northwestern Scotland. The bottom of the sandwich in the left bottom corner of the picture is 540 million year old rock, the middle is 3.2 billion year old rock, and the top of the sandwich is 1.2 billion year old rock. The geology of the Moine Thrust is still being studied due to the complex nature of the rocks in the area.
Figure 3. Summary map of the Ross of Mull (Isle of Mull off the West coast of Scotland) based on five field localities. The areas that are boxed in and shaded darker are the field localities visited by our group with the rest of the map shaded based on interpretations of the area. This map is pretty typical of a final project that we were asked to complete for each region that we were in during field camp.

Evolution of the Arch of the Foot

Chimpanzee and human midfoot motion during bipedal walking and the evolution of the longitudinal arch of the foot
Nicholas B. Holowka, Matthew C. O’Neill, Nathan E. Thompson, Brigitte Demes
Summarized by Time Scavengers contributor, Maggie Limbeck

What data were used? The only data that were utilized in this study were five male humans and two male chimpanzees that were recorded while walking. The scientists applied markers on the joints and other key points in the feet of both the humans and chimpanzees based on where they hypothesized to see foot motion in both species. These markers provided the data points that were analyzed in film after the experiment was completed.

Methods: 3D kinematic data (a human or chimpanzee foot in motion) was collected by recording the subjects walking at a self-selected speed for 11 meters. The researchers then selected representative steps for each subject to analyze the motion and utilization in certain regions of the foot. The data was analyzed using the packages ProAnalyst and MATLAB to calculate joint angles and estimate speed of walking. These angles were then used to determine the motion between the markers placed on the foot and understand the differences between human foot motion and chimpanzee foot motion.

Image of both a human and chimpanzee subject while walking. The dots on each foot indicate the markers that the researchers were using for data collection. The percentages on each image indicate the amount of motion in the midfoot that is being utilized during each part of taking a step.

Results: It was found that humans have a much greater range of motion along the sagittal plane (imaginary plane that divides the body into left and right sides) than chimpanzees, but the range of motion along the coronal plane (imaginary plane that divides the body into front and back) were similar in both species. While there were some great differences in motion along other planes the results state that the motion and parts of the foot involved are still activated at some point while walking, they are just activated during different parts of walking in chimpanzees and humans.

Why is this study important? This study is important because it was thought that the arch in human feet evolved to stiffen the foot while walking upright on two legs (bipedally) and that therefore chimpanzees would have a much greater motion in the midfoot than humans would while walking bipedally. This experiment rejects that idea because it was found that humans actually use a significantly greater amount of motion in the midfoot while walking than chimpanzees. This does not however, mean that at all times when walking do humans have more motion in their midfoot. The researchers broke walking into separate phases and during some of those phases the chimpanzees did have much more motion in their feet than humans; but when looking at the step as a whole, humans do have more motion than chimpanzees.

Big picture: The big picture here is that the total difference in range of motion between humans and chimpanzees is pretty small, only 4°. Therefore we can’t rely on using only midfoot joints to explain evolutionary differences between humans and chimpanzees. The authors suggest that looking further into morphology (shape) affects the function of the midfoot throughout motion. Essentially, evolution cannot always be easily explained by differences in bone shape–we must observe the action that the bones might be influencing.

Citation: Holowka, N.B., O’Neill, M.C., Thompson, N.E., Demes, B., 2017, Chimpanzee and human midfoot motion during bipedal walking and the evolution of the longitudinal arch of the foot: Journal of Human Evolution, p. 23-31.

Switching Up the Dinosaur Family Tree

A new hypothesis of dinosaur relationships and early dinosaur evolution
M.G. Baron, D.B. Norman, and P.M. Barret
Summarized by Time Scavengers contributor, Maggie Limbeck

What data was used? This study looked at a wide range of dinosaurs and dinosauromorphs (dinosaur-like animals) including those from around the world from the Middle Triassic to Cretaceous. The data were focused on the early dinosaurs, from which there previously wasn’t a lot of focus on evolutionary studies. By studying the fossils of all of these different dinosaurs the researchers were able to find similarities and differences in their morphologies (structure, shape, function) to create a character list to be used to create a new phylogenetic hypothesis (evolutionary hypothesis) for dinosaurs.

Methods: The character list that was created by studying the fossils of the dinosaurs in question was scored for each dinosaur. This means that every dinosaur had the same questions asked about it and answered as a yes/no question. This data set was then run through TNT 1.5-beta, a phylogenetics software that generates a phylogenetic tree based on those characters. After a new tree was created based on this data it was tested for support using Bremer support (which calculates the difference between the most parsimonious tree and the next most parsimonious tree that is missing a particular clade (grouping of organisms)) and constraint trees.

Results: The major result of this study is the reorganization of the dinosaur phylogenetic tree that changes the relationships that were thought to be true since 1887. Since that time the theropods (e.g., T. rex) and sauropods (e.g., Apatosaurus and Brachiosaurus) were thought to form a group because their hips have a classic “reptilian-hip” structure while ornithischians (Triceratops) have a “bird-hip” structure. After completing this study, it was found that contrary to this belief that the groups Ornithischia and Theropoda are more closely related to each other than Saurischians and Theropoda are. Additionally, this new hypothesis of the evolutionary relationships between the major dinosaur groups helps to provide an explanation for morphological features that were previously thought to be examples of convergent evolution (similar traits shared by organisms that are not closely related) between theropods and ornithischians.

The newly hypothesized phylogenetic tree for dinosaurs. B shows the reorganization of Ornithischia (bird hipped dinos) to be most closely related to Theropoda (T. Rex style dinos). This is different than the relationship that was believed since 1887 that Theropoda and Saurischia were most closely related.

Why is this study important? This study is important because it represents a critical shift in the way that we think about and study dinosaurs. A change in the evolutionary relationship between major groups of dinosaurs will require current studies to evaluate how this change may affect their results. However, this could aid research that had unanswered questions or odd data points that may now be explained by these relationships.

Big Picture: The big picture with this study is that even things that we as scientists and science enthusiasts have thought to be true for years can be redefined. We see here that the dinosaur “family tree” has changed dramatically with just this one study. However, this paper has sparked a lot of internal fact-checking and conversation that is an integral part of science that is often forgotten or hidden in the background. Many scientists have run their own phylogenetic analyses and have used different methods to decide if what these authors are claiming is, in fact, correct. All phylogenies are just hypotheses, especially with dinosaurs since we only have fossil data to use. Fossils are not always in the best shape to help us learn from them, and especially fossils from the early Triassic are lacking. By having the scientific community be so shaken by this news and running their own analyses, they are helping to strengthen the validity of this science and making it more powerful. So while yes, this is groundbreaking science, it is also a good reminder that scientific hypotheses are still extensively tested and retested parts of science, not just a guess or a hunch.

Citation:Baron, M.G., Norman, D.B., Barret, P.M., 2017, A new hypothesis of dinosaur relationships and early dinosaur evolution: Nature, p. 501-506.