Bethany Allen, Computational Paleobiologist and Education Outreach Fellow

Fossil hunting at Robin Hood’s Bay, North Yorkshire, UK. Photo credit: Alex Dunhill.

I am currently a PhD student at the University of Leeds, UK. My research looks at the role of mass extinctions in driving long-term trends in ecology and evolution. I do this by analysing large volumes of data from the fossil record, which requires statistical programming, an approach often termed computational paleobiology.

I’ve always enjoyed the problem-solving nature of science; it can be frustrating at times but really satisfying when all of the pieces of the puzzle fit together. As an undergrad, I studied Biology and Earth Sciences at Durham University, UK, before going on to complete a Masters in Palaeobiology at the University of Bristol, UK. Both of these courses helped to cultivate my passion for evolutionary biology, and equipped me with the scientific approaches and data analysis skills I needed to tackle “big data” questions in paleontology.

Admiring the museum collections at Galerie de Paléontologie et d’Anatomie comparée [Gallery of Paleontology and Comparative Anatomy] in Paris, France, with fellow paleontologist Vishruth Venkataraman. Photo credit: Rhys Charles
My PhD project is focused on comparing large-scale spatial patterns of biodiversity (=the variety of life in an area or on a global scale) before, during and after the Permian-Triassic mass extinction event (~250 million years ago), the most severe mass extinction event in Earth history. During this time,  up to 95% of marine species became extinct. Widespread volcanic activity drove extreme global warming, leading to ‘hothouse’ conditions which prevented ecosystems (=a community of animals and how they react with the environment around them) from fully recovering for several million years. Understanding how global warming has affected the biosphere in the past is important for making accurate predictions of how global warming will affect animals and plants in the future.

Most of my data comes from the Paleobiology Database, a global database of fossil occurrences compiled by paleontologists, which is freely accessible to everyone (you can explore the data using the Navigator app). As one of the data enterers, I spend a lot of my time looking for information on fossils published in journals and books and adding them to the database. Once I’m happy with my occurrence data, I analyse them using R, a programming language and environment designed specifically for statistics. It enables me to carry out complex calculations across big data sets relatively quickly, to establish what the fossils are telling us about large-scale evolutionary patterns.

Volunteering with the Palaeontological Association at the Yorkshire Fossil Festival in Scarborough, UK. Photo credit: Jo Hellawell.

I also really enjoy outreach. Alongside my PhD, I work part-time delivering environmentally-themed school sessions, building on the experience I gained doing outreach with the Bristol Dinosaur Project during my Masters. At present, I’m particularly involved in delivering ‘Fossil Hunt’ sessions, visiting local schools to give 7-11 year olds the opportunity to handle fossils and learn about paleontology. It’s great to be able to show the children what ‘real’ scientists look like, and I always leave refreshed by their enthusiasm.

I love my research because it strikes the perfect balance between being something I’m really interested in (evolutionary biology) and requiring something I’m good at (data science). My advice to aspiring scientists would be to find this crossover in your own skills and interests – science takes perseverance, and that’s much easier when you’re making the most of your talents and are passionate about what you’re doing!

Follow along with Bethany, her research, and her education outreach activities on Twitter Meet the Scientist, Published

Preparing Samples for Stable Isotopic Measurements

Adriane here-

Recently, Andy and I have started to collaborate on a research project together. Well, the project is his, and I’ve agreed to do some lab analyses for him in exchange for being a co-author on the research paper. Being a co-author means that on a published journal article, I will have my name as one of the people who contributed to the science in the paper. My job for this project is to pick, weigh, and analyze foraminifera for stable isotope analyses. In this post, I’ll go over briefly how I do this!

Lucky for me, Andy had already picked the foraminifera he wanted to be analyzed from his sediment samples and put these into cardboard trays. Each tray is labeled so that it corresponds with the sediment sample from which it came, thus I know exactly which sample I’m working with. The first step is to take the cardboard tray and put it under the microscope. Using a paintbrush with water, I gently pick up the foraminifera specimens and place them in an aluminum tray. After I’ve filled up all 14 of my aluminum trays, I take these and weigh them on a microbalance, which is a fancy name for a scale that measures very small weights (in this case, micrograms). I want the samples to weigh between 180 to 220 micrograms, as this is the ideal mass needed to get a good measurement. After the samples are weighed, I then put them into a tall glass vial that is numbered. I have a spreadsheet on my computer where I keep track of which sample is in which vial.

The home-made device we use to pump helium into the vials and air out. We fill 10 vials at a time for about 4-5 minutes each.

After I have about 60-80 vials of weighed foraminifera, I can then begin the process of analyzing them for stable isotope measurements. In this case, we want to measure carbon and oxygen (see our ‘Isotopes‘ and ‘Carbon & Oxygen Isotopes‘ page for more details on what these data are used for). This process is a bit tedious and always makes me nervous, but it’s also kind of fun!

The acid is poured into a syringe with a needle, and then four drops of acid are inserted into each vial. It’s a very medical-like procedure for a geologic endeavor!

Analyzing foraminifera for stable isotopes means working with a mass spectrometer, a (very expensive) machine that, very simply put, measures the amount of carbon and oxygen that are within a gas. Notice that the mass spectrometer needs a gas, not a solid, to be able to take a measurement. This is where things get fun! The first step is to make sure all of the air is out of the glass vials. To work correctly, the mass spectrometer has helium constantly being pumped through it. No air is allowed into the system, as air contains oxygen, and oxygen is one of the elements we want to measure. If air gets into the mass spectrometer or into the vials, it’ll ruin the results of the analyses. To rid the vials of air, I put the vials on a contraption that continually pushes helium into the vials through one tube while letting air out of another small tube. I let the vials fill with helium for about 4 minutes each. After the vials are filled with helium, I then put acid into each vial. Four drops of 100% pure phosphoric acid is placed into each vial. This is done to turn the foraminifera, which are made of calcium carbonate, into gas (any acid placed on calcium carbonate, the material which seashells and foraminifera are made of, will cause them to dissolve). Because calcium carbonate is CaCO3, the resulting gas includes elements of both C (carbon) and O (oxygen).

Once all the vials are filled with acid, it’s then time to start the mass spectrometer! This is a very easy process considering the machine itself is complex and intimidating (well, at least to me). In short, I basically change the file names, make sure the machine knows how many samples its analyzing, and then I click the ‘Start’ button. Each sample takes ~12 minutes to analyze, so an entire run of 60 to 80 samples takes about 12 to 16 hours.

The last part of this process will be to take the results, put them into a spreadsheet, and give them to Andy. From there, Andy will have the hard but fun job of interpreting the data and writing the majority of the research paper (with help from us, when needed).

Antarctica’s Ice Sheet Sensitivity to Warming 23 to 14 Million Years Ago

Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

Richard LevyDavid HarwoodFabio FlorindoFrancesca SangiorgiRobert TripatiHilmar von EynattenEdward GassonGerhard KuhnAradhna TripatiRobert DeContoChristopher FieldingBrad FieldNicholas GolledgeRobert McKayTimothy NaishMatthew OlneyDavid PollardStefan SchoutenFranco TalaricoSophie WarnyVeronica WillmottGary ActonKurt PanterTimothy PaulsenMarco Taviani, and SMS Science Team

The Problem: The early to mid-Miocene (23 to 14 million years ago) is an interval of geologic time where atmospheric carbon dioxide (CO2) concentrations (about 280 to 500 parts per million) were similar to those that are projected for the coming decades under human-induced climate change. Thus, this interval of time is interesting for geologists because we can use the geologic record from this time to interpret how our oceans, atmosphere, and ice sheets ‘behave’ under warming scenarios. Understanding the extent to which the Earth will warm, weather patterns will change, and sea levels will rise in the coming decades can help scientists, the public, and policy makers prepare for our future. Related to sea level rises is understanding how much continental ice sheets, such as those on Greenland and Antarctica, will melt.

Map of Antarctica with a red dot denoting where the ANDRILL core was drilled.

In this study, geologists use several methods to determine how sensitive Antarctic ice sheets are to increases in atmospheric CO2 concentrations 23 to 14 million years ago. The results from this study are useful in that we can determine how much Antarctic ice may melt in the coming decades, which would add to sea level rise.

Methods: To interpret how sensitive Antarctic ice is to atmospheric warming (or increased average global warming), the scientists use sediments obtained in a drilled core from the coastal margin of Antarctica (an ideal location to study the melting and growth of ice sheets). The core was drilled in 2006 and 2007 as part of the ANDRILL (ANtarctic DRILLing Project) scientific drilling project from the McMurdo sector of Antarctica. The core is approximately 1,138 meters long, and contain sediments that are dated at over 20 million years old!

This study is very unique and fun because the scientists use several proxies (or naturally-occurring records) to interpret what the margin of Antarctica looked like through time. The presence and abundance (or numbers) of plankton (such as foraminifera) and pollen grains indicate when the margin of Antarctica was warmer, and ice sheets had melted back. For example, when the ice around Antarctica melted back, this allowed more room and soil for plants to grow. The lithology, or general characteristics of the sediments and rocks collected in the ANDRILL core, was also used as a clue to the changing environment of Antarctica through the study interval. Just knowing the different sediment types through time is a very powerful proxy itself!

Results: Using all the different methods and proxies, the geologists were able to interpret how Antarctic ice sheets melted and re-grew through the Miocene interval. They determined that several times from 23 to 14 million years ago, ice grew and retreated inland. They found that Antarctic ice becomes very sensitive to small changes in the amount of carbon dioxide in the atmosphere.

Four environmental motifs as defined by the authors of the study. The location of the ANDRILL core used in the study (A2A) is noted in each image. Notice how the ice sheet retreats from I to IV as the amount of carbon dioxide in the atmosphere increases through time.

To best illustrate their findings, the authors of this study created four ‘environmental motifs’. These are images of what the scientists think the Antarctic margin looked like through time. Note that there are only four motifs; these just capture the major environments that the scientists inferred from their data. There were likely other ‘in-between’ environments. But notice how dynamic the ice sheet around the Antarctic margin were: the ice melted and then re-grew quite a bit in response to warming and cooling events through the Miocene!

Why is this study important? This study highlights and solidifies the hypothesis that Antarctic ice sheets were very sensitive to changes in atmospheric carbon dioxide concentrations during the Miocene. The findings of the study also indicate that Antarctic ice will behave similarly under increased warming predicted for Earth’s future. Melting ice will have a huge impact on sea level, which will make living on coastal lands hard or impossible due to flooding.

Citation: Levy, R. H., Harwood, D., Florindo, F., Sangiorgio, F., Tripati, R., von Eynatten, H., Gasson, E., Kuhn, G., Tripati, A., DeConto, R., Fielding, C., Field, B., Golledge, N., McKay, R.,, Naish, T., Olney, M., Pollard, D., Schouten, S., Talarico, F., Warny, S., Willmott, V., Acton, G., Panter, K., Paulsen, T., Taviani, M., and the SMS Science Team, 2016. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene. PNAS 113(13), 3453-3458. doi: 10.1073/pnas.1516030113.

Dr. Rehemat Bhatia, Foraminifera Geochemist

Rehemat looking at foraminifera under the microscope

What is your favorite part about being a scientist, and how did you become interested in science?

Throughout my time in middle school, my favourite lessons at school were always biology, chemistry and physics. I also really enjoyed physical geography, and  my teachers at school were always enthusiastic, engaging and were more than happy to support my interest in geology. They pointed me in the right direction with careers when I was in high school, and without their guidance I probably wouldn’t have studied geology at university. I also volunteered at the Natural History Museum in London from the beginning of my third year of undergrad with an EU funded research project called Throughflow (as part of the V Factor Volunteer Scheme). The researchers who I volunteered with were also incredibly encouraging and supportive, and great mentors too.

I enjoy being a scientist because:

  • I get to look at microfossil specimens that no one has looked at before. Foraminifera are so pretty, and I still can’t believe that these single celled organisms manage to create these ornate skeletons which record climate during their lifetime! Understanding the stories they have locked up inside is sometimes a little difficult, but I enjoy the challenge that this presents.
  • Lab work is fun. I love learning different chemical techniques.
  • I get to meet lots of awesome people from a variety of backgrounds and geological disciplines and talk science with them.
  • I get to communicate my science to public audiences and inspire new generations of scientists.

What do you do?

I use the chemistry of fossil plankton called foraminifera to understand more about their ecologies and what the climate was like millions of years ago.

How does your research contribute to the understanding of climate change, evolution, or to the betterment of society in general?

We use chemical data from foraminifera shells to reconstruct past climate. However, we don’t fully understand all aspects of foraminiferal ecology i.e. exactly what their lifestyles were like- did they all live with algae? Did they migrate or change in size because oceans became harder for them to live in? Ecology affects shell chemistry. Thus, before we put together long term climate records to understand how the earth’s climate has changed through time using chemical signals from foram skeletons, it is important to understand the controls on the signals that we use. This is particularly pertinent to geological periods that we use as future climate analogues such as the Eocene (~47-33 million years ago).

A picture of a foraminifera (taken with a microscope) that has been blasted with Rehemat’s laser! Where the holes are is where the laser was used to measure the different amounts of elements in the shell.

What are your data and how do you obtain them?

Planktonic foraminifera are single celled plankton which have a skeleton made from calcium carbonate. Some species choose to live in the surface waters of the ocean, whilst others choose to live in the thermocline. Some even live together with algae! All forams are beautiful, and they come in all sorts of shapes and sizes. Foraminifera are really awesome too, because in the same way human hair records our diet, their skeletons record the environmental conditions around them in the ocean. By the analysis of one shell, we can understand the climate in the location and the time that the foram lived, including how hot the oceans were and even how much ice there was on land!

When foraminifera die, their skeletons sink to the sea floor and build up in layers, creating an extensive fossil record more importantly an extensive climate record too! The same signals we use to infer climate in the past can tell us how they used to live too i.e. their ecology.

To understand foraminiferal ecology, I use several geochemical proxies. Proxies are chemical signatures which are an indirect way of understanding an environmental parameter. I primarily use  oxygen isotopes, carbon isotopes and the amounts of magnesium (Mg), strontium (Sr) and boron (B) (ratioed to calcium, Ca) in foraminiferal shells. If these elements are unfamiliar to you, you might not have realized you’ve seen them before. White fireworks have Mg, green fireworks have B and red fireworks have Sr! I gather these data using different machines called mass spectrometers and electron microprobes. One of the mass spectrometers I use is hooked up to a laser, which is super cool. I use the laser to drill through foram shells to understand how Mg, B and Sr vary through the shell wall. Mg/Ca, Sr/Ca, B/Ca, δ18O and δ13C signatures are specific to certain species. For example, a surface dwelling species will have greater Mg/Ca and a more negative δ18O signature. Therefore if I collected these type of data from a species with an unknown ecology, I would infer that it was a surface dweller.

What advice do you have for aspiring scientists?

  • Always be curious.
  • Ask as many questions as you can – no question is stupid. If someone tells you your question is stupid – they’re wrong.
  • Talk with lots of people who might be able to help you gain more of an insight into the world of science. You never know who might be able to give you work experience/research internships/jobs (both academic and non academic).
  • If things go wrong academically early in your career, don’t let that stop you from progressing later on. Work hard, learn from your mistakes, and you can do anything you’d like to (I speak from experience with this one…)
  • Have mentors and a support network. I wouldn’t have survived the final stages of my PhD without mine.
  • Look after yourself – no science is worth you burning out over. As a friend once told me – the forams will still be there and waiting for you to look at them in the morning… (they’re not wrong).
  • For those studying for exams (including PhDs): Don’t lose your enthusiasm and don’t give up if things get tough. You set out to learn/research something cool, and if you’ve made it this far, you can totally do it!

Learn more about Rehemat’s research and follow her on Twitter @rehemat_

Memories of a Glacier in the Connecticut River Valley

Adriane here-

An image depicting the extent of ice over North America during the Last Glacial Maximum. The main glacier that covered New England was called the Laurentide Ice Sheet, whereas the smaller glacier that covered parts of western Canada was called the Cordilleran Ice Sheet.

Every Semester, the University of Massachusetts Amherst Department of Geosciences offers the class Introduction to Geology. The course is designed for undergraduate students who need science credits for their degree, but it is also a required course for our geoscience undergraduate majors. The course has a lab that complements and expands on topics that are covered in lecture, such as  plate tectonics, igneous, metamorphic, and sedimentary rocks, river dynamics, topography, and the history of how the Connecticut river valley was formed. The labs are run by four to five teaching assistants, graduate students who are pursuing their master’s or PhD degrees. We take the students on two field trips as part of their labs: the first trip is to look at geologic features in the valley leftover from the glaciers, and the second to look at the major rock formations in the valley.

This post is about the glaciation that ended around 20,000 years ago, and the imprint the ice and ice melt left on this area of western Massachusetts. This time of huge ice sheets that covered northern North America, Europe, and Asia is referred to as the Last Glacial Maximum. In North America, the glaciation is referred to as the Wisconsin Glaciation. The glaciers that covered North America reached their maximum southern extent about 26,000 years ago, after which the ice began to melt and retreat back to the north. At the glacier’s maximum extent, Massachusetts was totally covered by ice. Estimates based on how thick the ice was range from 1 to 2 kilometers  (0.62-1.24 miles)! That’s a ton of ice! Because ice is very heavy, it depressed the Earth’s crust below it. In southern New England, the ice is estimated to have depressed the Earth’s crust down by about 50 meters (~165 feet; Oakley and Boothroyd, 2012). Once the ice melted, the crust of the Earth began to pop back up. This phenomenon is called isostatic rebound. Satellites that measure the rate of isostatic rebound indicate that parts of Greenland and Canada, where the ice was thickest, are still popping back up today.

A shematic map of New England depicting the location and size of Glacial Lake Hitchcock. The maximum extent of the Laurentide Ice Sheet is depicted by the solid line towards the bottom of the image (Rittenour et al., 2000).

Back at a more local scale, there are several features around UMass Amherst that we, the graduate students that teach the Introduction to Geology labs, can identify that were created as a direct result of the glaciers in this area. I’m going to take you on our glacial field trip virtually, so that you, too, can get a first-hand look at the types of geologic features the glaciers left behind! First, a fun aside: There are several large boulders all over campus that, at first glance, look like they were placed in specific locations for an aesthetic affect. Upon closer inspection, the boulders are made from a certain rock type that occurs in our valley. Glaciers, and ice, act as bulldozers, and have no problem picking up and carrying huge chunks of rocks. These boulders, then, were picked up from the nearby hills and deposited all over the valley, with some ending up on our campus! These boulders aren’t part of our field trip, but are neat nonetheless.

The varves at UMass Amherst that are the sediments that made up the floor of Lake Hitchcock. The different bands are clearly visible, but the dark and light colored bands aren’t obvious when the soil is wet.

The first stop on our field trip is right on campus, behind our football stadium. Here, there is a small creek with about 5 feet of the upper part of the soil profile exposed. But there’s something special about the soil here: it is unlike anything found in other places of the world: varves! Varves are alternating bands of dark and light-colored clay layers that made up the bottom of a lake that used to cover the valley. The lake was created once the glaciers began to melt, leaving more parts of Massachusetts exposed. The meltwater from the glaciers flowed via river into the Connecticut River Valley, and became dammed here. This created Glacial Lake Hitchcock. The varves are remnants of the sediment that collected on the bottom of this lake. Varves are awesome because they record climate changes on a seasonal basis! The dark bands contain finer clay particles, and are deposited during the winter months when there is less sediment being brought into the lake by the river (during the winter months, there is less glacial melt, and thus less water flowing in the rivers). Lighter varve bands are usually made of coarser (or larger) grains and are deposited during the spring and summer months when glacial melting increases, bringing more water and thus sediments into the lake. By counting the pairs of dark and light varves, scientists can estimate how old Glacial Lake Hitchcock was. Varves from the lake were counted by scientists at UMass Amherst, and they found that the lake was around for at least 4,000 years, from 17,5000 to 13,5000 year ago (Rittenour et al., 2000)!

A kettle pond near UMass Amherst.

After checking out the varves, our second stop is a kettle hole a few miles from campus. A kettle hole is a depression in the Earth formed from a chunk of ice that broke off from the retreating glacier. The ice chunks become buried by glacial outwash, or the mix of water and sediment that spreads across the land as the glacier melts. Thus, the ice chunk is completely buried by sediments. After some time, the chunk also melts, which then creates the kettle hole. These features are prominent throughout New England, and are usually small in size.

The Sunderland Delta (left panel), with topset and foreset beds highlighted for clarity (right panel).

The third stop on our glacial field trip is to the Sunderland Delta. A delta is a place where a river meets a larger body of water, like a large lake, ocean, or sea. Some rivers flow fast, and some flow slower. In general, the faster a river flows, the more sediment it can move and carry. I mentioned earlier that the glacier began to melt back, and that melt water was transported by a river into Glacial Lake Hitchcock. The river was quite large, and had the ability to move sand-sized sediment. But where the river met the calm waters of the lake, it lost its velocity, and thus its ability to carry sediment. The sediment was then ‘dropped’ at the mouth of the river where it emptied into Glacial Lake Hitchcock. This dropped sediment formed a delta, or an area where fine-grained sand was deposited. This sand accumulated over thousands of years. Today, these sand deposits that make up the delta are mined by humans for use in concrete and manufacturing. There are several open mining pits around the university, but one in particular preserves the features of the delta, namely topset and foreset beds of sand. When the river gets close to the larger body of water, it begins to slow down. The loss of velocity leads to the river dropping some of its sediment it is transporting. This sediment is laid down in thin sheets that lie flat. These sediments form topset beds. Where the river meets the body of water, it is slowed even more, and the rest of the sediment it carries is dropped. These particles form a slope down into the lake, and make up the sloping foreset beds.

Once the students understand how the Sunderland Delta was formed, we then move downhill to our fourth stop: a trout hatchery right down the road. This, by far, is the coolest stop, as it contains a unique geologic feature: a natural spring! At our first stop, you saw that the base of Lake Hitchcock was composed of very fine sediment called clay and silt. Clay and silt grains are flat, and when they are compressed over time, they don’t allow water to pass through very quickly. In the introduction paragraphs of this post, I also explained how the Earth’s crust underneath New England, including Massachusetts, popped back up, or rebounded, after the overlying weight of the glaciers was gone. When the land began to rebound, that caused the clay layers of the lake to crack. When this happened, the groundwater that was stored deep in the sediment under the clay was able to come to the surface. Here, at the trout hatchery, is one of the places the groundwater is able to come to the surface via cracks and conduits in the thick clay layers! It can be seen bubbling to the surface continually throughout the year. The video below shows the spring in action:

A view of one of the trout ‘tanks’, where the spring water feeds into the top tank and trickles down to the two other rows of tanks below.

The water stays a constant temperature year round because it originates from so deep within the sediment. The constant temperature and clarity of the water is great for raising trout, because the water rarely, if ever, freezes during the winter and is never too hot during summer months! The trout that are raised at the hatchery are released into local streams and rivers so that fishers do not over-fish the local populations. This stop is one of my favorites, as it is an excellent example of how geology and biology go hand-in-hand, and how the geologic processes of the past are relevant and useful today.

Our fifth and final stop is just down the road from the trout hatchery. The feature here is not as impressive or obvious after the large delta feature and the natural spring, but it records an important phenomenon related to the retreat of the glaciers nonetheless. On the side of the road is a small hill that most local folks pass by probably everyday. This hill is covered in trees and vegetation, and one might totally overlook it quite easily. But if you stop and dig down 4-5 inches through the roots and topsoil, you’ll hit sand!  This small hill is, in fact, a sand dune that was formed from winds towards the end of the Last Glacial Maximum.

A hole I dug in the side of the glacial dune. Notice the darker sediment (made of rotting leaves and roots) towards the top of the hole. The base of the hole is lighter in color, as that is the sand!

When the glacier that covered Massachusetts began to melt back, the Earth was beginning to warm up. The area to the south of Massachusetts was becoming warmer, but on top of the glacier to the north, the air temperature was still very cold. This difference in air temperature, or temperature gradient, created strong winds that blew from the warmer regions towards the colder regions. This phenomenon happens today at the beach: during the day, the wind blows towards the ocean from the hot land; but at night, the wind direction changes as the land cools down until it is cooler than the ocean water. The beach is also characterized by sand dunes,which are the products of these strong winds depositing small sand grains behind the beach. Just like at the beach, the strong winds moving towards the glacier picked up small sand grains and deposited in the valley near UMass, where they are still visible today!

The features that we show our undergraduate students and that are explained here are just a few features in our valley that are leftover from the massive glaciers that once covered the land. All around New England, there is evidence of the heavy ice that was once here not too long ago: exposed rock where the glaciers scraped away soil; glacial striations, or scratches, in the exposed rocks from the glaciers moving over them; and potholes in the bedrock near the rivers, where melted water mixed with larger pebbles and boulders under the ice to carve out rounded holes in the rocks. If you’re ever in New England, keep your eyes peeled for evidence of the glaciers; it’s literally everywhere!

Bedrock, or very old rocks that underlie the soil of western Massachusetts, that were scraped clean by the glaciers in Shelburne Falls.



Oakley, B. A., and Boothroyd, J. C., 2012. Reconstructed topography of Southern New England prior to isostatic rebound with implications of total isostatic depression and relative sea level. Quaternary Research 79, 110-118.

Rittenour, T. M., Brigham-Grette, J., and Mann, M., 2000. El-Nino Like Teleconnections in New England during the Late Pleistocene. Science 288, 1039-1042.

Kevin Jiménez-Lara, Paleomammalogist and Paleobiogeographer

Kevin taking photographs of a fossil anteater skull deposited at the fossil mammal collections at the Field Museum in Chicago, IL.

First, let me introduce myself. I am a Colombian PhD student at the National University of La Plata, Argentina. My research is focused on the evolution of xenartrans, mammals that include armadillos, sloths, and anteaters.

Since I was a child, I have had a strong fascination to learn about nature. For that reason, I loved (and I still do love) reading a lot and watching documentaries about science, wildlife, meteorological phenomena, the history of the Earth, the history of the Universe, astrophysical theories and hypotheses, and other similar topics. Science has an amazing explanatory power, and that has always been what I like most about it. Science allows us to know our place in the Universe.

Following my vocation, I studied biology in college. Although during my undergrad there were many disciplines that caught my attention, the only one that enamored me was the study of extinct life forms, i.e. paleobiology. At first glance, it is not easy to explain why I wanted to be a paleobiologist, since there are very few Colombian paleobiologists and institutions that teach paleobiology and/or develop paleobiological research in my home country. However, studying the unique history of evolution of living beings seemed not only a noble, respectable activity, but it also became a passion that I believe will always accompany me as long as I live. Paleobiology has formed the basis of my life in the professional field, and also in a personal, philosophical sense.

Kevin doing paleontological prospecting and fossil collection in the La Venta area of southwestern Colombia. In this area some of the most important fossil assemblages of tropical continental vertebrates can be found.

To perform research in paleobiology in a country located in the intertropical belt of the planet (near the equator) and characterized as one of the most biologically diverse areas on Earth poses great challenges and opportunities. On the one hand, there is little or no state support to study paleobiology as a consequence of socio-historical development. In addition, there are limitations related to logistics in regions that are difficult to access due their geographic location and/or security features. We also face scarcity of continuous outcrops of sedimentary rocks where fossils can be found. Often, as a result of climatic factors and abundant vegetation (plant life), fossils are poorly preserved (however, sometimes, they are exquisitely preserved!). But these limitations are largely compensated by huge opportunities. Fossils from the tropics are exceptionally valuable. They document innumerable evolutionary stories that can help explain one of the most disturbing questions for many biologists: why is there a tendency in different groups of living organisms to present greater diversity in the intertropical zone compared to other regions on Earth, such as in higher latitudes?

Paleobiology in the tropics is very necessary because of the generalized geographic bias in research of many extinct organisms and periods of Earth’s history. Namely, most research on these topics has been conducted in Europe and North America. In Colombia, paleontological field expeditions and studies have yielded surprising findings, including, of course, our flagship fossil organism (in my opinion): Titanoboa (Titanoboa cerrejonensis). For all those who do not know it, this snake lived approximately 60 million years ago in the extreme north of Colombia (Guajira peninsula), and its most surprising feature is its size and body mass. Titanoboa measured about 13 meters in length and could exceed one metric ton in weight. That makes it the largest known snake of all time!

Artists’ rendition of Titanoboa in its natural habitat, a very warm and humid tropical forest in La Guajira, northern Colombia, around 60 million years ago. Other reptiles of this time period were also giants, such as crocodiles and turtles.  Image by Jason Bourque.

I contribute to tropical paleobiology by studying fossil xenartrans (armadillos, sloths, and anteaters), particularly those that lived in northern South America and southern Central America. I seek to clarify questions on evolutionary/phylogenetic relationships between extinct representatives of these charismatic mammals and, at the same time, to reconstruct historic changes in their geographical distributions (where they lived through time).

Why is it important to study extinct armadillos, sloths, and anteaters? There are many reasons, but my favorite is that they are animals whose origin and evolution are closely related to great-magnitude abiotic (non-biological) events and processes (such as climate changes and tectonic events). Through tens of millions of years, abiotic factors shaped their biology and ecology to configure the xenartrans in one of the most peculiar mammals that existed during the Cenozoic (the last 65 million years). Have you seen how strange some armadillos look when they roll into a ball, or the very slow movements of a three-toed sloth, or the long tubular snout of a giant anteater? If you have not seen this, you should check out the videos linked in the previous sentence. But in the fossil record we know even more bizarre features of xenartrans than we see in living species. For example, several species of giant sloths used to swim (yes, you read it right, ‘swim’) in littoral zones (areas close to the beach) of western South America around 5 million years ago! Is that not mind-bending?

Several species of the giant sloth genus Thalassocnus could swim in shallow marine habitats off the west coast of South America (Peru and Chile) during the late Miocene-Pliocene (7-4 million years ago). Paleobiologists know this primarily from studies on anatomical adaptations to swimming indicated from the animal’s bone structure. Image by Roman Uchytel.

Xenartrans constitute an outstanding study model on how Earth and life evolve together, from their evolutionary differentiation ~98 million years ago, possibly triggered by the geographic separation of Africa and South America, until their colonization of North America during the last 9 million years in the environmental framework of the Panama Isthmus uplift and the Last Great Glaciation. This makes xenartrans interesting organisms to study evolutionary patterns and processes of high complexity in the tropics.

I am particularly interested on the evolutionary implications (diversification) of dispersal (or movement) events of xenartrans from northern South America to North America (including its ancient Central American peninsula) during geologic intervals which immediately precede the definitive formation of the Isthmus of Panama. Long distance dispersal through a shallow sea, like that which existed between southern Central America and northwestern South America before the complete isthmus emergence, is one of the least understood biogeographic phenomena. The explanatory mechanism of long-distance dispersal allows for disjunct distributions and for us to more comprehensively understand the subtle interaction between distinctive faunas of contiguous areas.

In order to fulfill my general research objective, it is necessary to work hard in determining identities and affinities of Middle-Miocene to Pliocene (15-2 million years old) xenartrans of the aforementioned regions, including not only previously collected fossils, but also new findings. In a complementary way, it is required to put identifications in geographic context through faunal similarity/dissimilarity methods. I also use probabilistic biogeographic models (models that use statistics) to infer major distributional patterns and processes of several subgroups of xenartrans, so that we could understand in an analytic, non-strictly traditional narrative way, the changes of their occurrences in space. Finally, long distance dispersal events through poorly suitable environments for most xenartrans, like shallow seas, are approached through locomotive reconstructions to estimate dispersal capacity (vagility).

I want to end this post by giving an important advice to all those who aspire to be scientists. The path to work in science may be, to a greater or lesser extent, long and complex. However, if you remain true to your convictions and strive under a regime of self-discipline, you will not only be a scientist, but also one of the most prominent researchers in your field. Question everything, do not firmly hold onto hypothesis that have little associated evidence. And, above all, write, write to clarify in your mind many issues related to your research.

To learn more about Kevin and his research, check out his blog called ‘Caribe Prehistorico’. To find this post in Spanish, head to Kevin’s blog by clicking here.

Dipa Desai, Paleoclimatologist & Educator

Dipa working in Colorado with the National Park Service.

What do you do?

I am a paleoclimatologist, and I study the ecological and environmental effects of climate change using the fossil record. Specifically, I research how the Ross Ice Shelf in West Antarctica responded to temperature and atmospheric CO2 concentrations slightly higher than what Earth will experience in the next several decades. The Ross Ice Shelf is currently the largest mass of floating ice in the world, and West Antarctica is currently melting faster than the rest of the Antarctic Ice Sheet–what’s going to happen when this much ice melts into the ocean? How will melting affect regional plankton communities, the base of marine food webs? When that much freshwater is added to the ocean, what happens to ocean currents and circulation? I’m interested in answering these questions and using research outcomes to improve environmental policies and climate change mitigation strategies.

I’m also an educator! I spent the last two years in the classroom teaching 5th and 6th grade STEM (Science, Technology, Engineering, Mathematics) classes, and I informally teach when I participate in STEM outreach events and programs. I plan to use my research as a model to teach the next generation of voters and environmental stewards about their planet’s historical and future climate change, and inspire the next generations of diverse, innovative STEM professionals. As an educator, I have seen how disparities in access to educational opportunities disproportionately affect low-income communities, communities of color, immigrants and non-native English speakers, and other traditionally oppressed and disadvantaged groups. As a member of these communities, I see a lack of representation and inclusion in STEM professions, and a gap in scientific literacy in our policymakers, so I want to use STEM education to affect greater social and political change.

What do you love about being a scientist?

I love learning about the Earth’s past–being the first person ever to see a fossil since its deposition, using clues in the fossil record to understand and imagine what the Earth looked like millions of years ago, and making connections to predict what our world will look like in the future. However, my favorite part of the job is telling other people about what I do! I can see folks light up when I mention I study fossils, and it’s cool to see how many people grew up wanting to become a paleontologist, just like me! I think most people believe paleontology doesn’t have any real-world applications but in reality, paleontology offers a unique perspective to understanding the modern environment. When I tell students, I see them get excited about science and all its possibilities: I remember when I judged the MA State Middle School Science Fair once year, a participant was amazed that you can use fossils to study climate change, and she asked what else can we study using fossils? It is exciting to share my career with youths, especially those who look like me, because their idea of what a paleontologist looks like and does changes when they meet me.

Describe your path to becoming a scientist. 

As a kid I loved dinosaurs and exploring outside, so I knew I wanted to be a paleontologist from an early age, but I wasn’t sure if I’d ever get here. Growing up as a child of undocumented immigrants, our family faced housing, food, and financial insecurities, so college seemed beyond our means. However, I received the Carolina Covenant Scholarship to become the first person in my family to attend college, and I studied Biology at the University of North Carolina at Chapel Hill (Fun Fact: Time Scavengers Collaborator Sarah Sheffield was my teaching assistant for Prehistoric Life class!). I completed a B.S. in Biology, and minors in Geological Science, Archaeology, and Chemistry.

While I was an undergraduate at a large research institution, I didn’t have a dedicated mentor or the cultural capital to know I should pursue undergraduate research as a stepping-stone to getting into graduate school. After graduation, I pursued research opportunities with the National Park Service in Colorado and the Smithsonian Tropical Research Institute in Panama, where I got the chance to conduct independent research projects, help excavate and catalog fossils, and teach local people about their community’s paleontological history. While in Panama, I became fluent in Spanish and wondered how I could use my new experiences and skills to communicate complex STEM concepts to broader audiences. I transitioned to teaching middle school for the next two years; I taught hands-on STEM classes to 5th and 6th graders in the largely immigrant community of Chelsea, Massachusetts. I enjoyed giving my students educational opportunities that will help them in the future, and the challenges my family faced in my childhood prepared me as an educator to understand how my students’ personal lives affected their learning in my classroom.

The experiences I pursued after my undergraduate career gave me the skills and clarity needed to develop and pursue a graduate research degree. I’m currently working on my Master’s/Doctoral joint degree in Geosciences at the University of Massachusetts at Amherst.

How do you communicate science? How does your science contribute to understanding climate change?

For my graduate research, I’m studying how warmer-than-present paleoclimates affected Antarctic ice cover and the paleoecology of the surrounding ocean. Specifically, I study the Miocene Climatic Optimum, when global temperatures and atmospheric carbon dioxide concentrations were slightly higher than they are today, and close to what we expect to see at the end of the century. Studying the deep sea records of this time period reveals how microfaunal communities (i.e. foraminifera) reacted to a rapidly warming global climate, and how changes in Antarctic ice cover impacted sea level and ocean circulation; this can be applied to improve climate models and future environmental policies.

I want to bring my research to public audiences through in-person, multilingual outreach at museums, schools, and other educational institutions, and through online media to make climate science accessible and improve scientific literacy. Using multimedia, interactive, and open-access platforms to communicate science not only reaches more people, but also fits the needs of many different learning populations; this is why I believe STEM disciplines need to move away from the traditional format of communicating findings in paid science journals and articles.

What is your advice for aspiring scientists?

Mistakes are the first steps to being awesome at something.

Try as many new experiences as possible.

Identify what skills you need to do the job you want, then identify opportunities that will give you those skills.

Find a career that you enjoy, you are good at, that helps others, and hopefully makes you some money along the way.

Volunteering at Amherst Regional Middle School

Dipa here-

This past December, I got the opportunity to share my research and interests in climate change with a group of curious middle schoolers at Amherst Regional Middle School in Amherst, Massachusetts!

Amherst Regional Middle School during a beautiful New England fall day.

The school partners with University of Massachusetts Amherst Graduate Women in STEM (science, technology, engineering, mathematics) organization to connect graduate researchers to middle school students through 20-minute Science SoundByte presentations. The 7th and 8th grade students get to enjoy the presentations during their lunch times and learn about a variety of STEM research. As for me, I get to practice explaining my research and sharing my interests to the next generation of researchers.

An example of a fossil ammonite that I used for my outreach with the middle schoolers.

While I was planning my presentation I knew I wanted to get these students thinking about climate change, since it is a problem that affects them too. The students talked with each other and then shared out what they knew about climate change, sea level rise, and their impacts on the environment–they knew so much! To explain how I use fossils to study climate change in the past, I gave the students marine fossils (fossil shark teeth, mollusks, ammonites, and corals) and asked them to draw the organism and its habitat. Did it live in the reef, open ocean, at the seafloor, or in the water column? If these fossils were found in the same location, what does this say about sea level over time in that place?

The students had fun getting to touch and look at fossils, and they worked together to solve how much sea level rose over time for the activity! It was great to be back in front of a class and talk to students about their interests in STEM and how we can work together to understand modern climate change.

How Much Did Antarctic Ice Melt 8 Million Years Ago?

Minimal East Antarctic Ice Sheet retreat onto land during the past eight million years

Jeremy D. Shakun, Lee B. Corbett, Paul R. Bierman, Kristen Underwood, Donna M. Rizzo, Susan R. Zimmerman, Mark W. Caffee, Tim Naish, Nicholas R. Golledge, & Carling C. Hay

The problem: There has been debate among scientists if the East Antarctic Ice Sheet melted substantially during the Pliocene (~5.3-2.6 million years ago) and Miocene (23-5.3 million years ago) when the amount of carbon dioxide in the atmosphere was higher (and thus the global average temperatures were much warmer). Some scientists think that as the Earth was warmer during this time, the ice melted back substantially, thus exposing some land surface on East Antarctica. Other scientists think this is not possible based on other lines of evidence. This study set out to investigate whether or not the ice sheet melted back and exposed land by measuring the amount of cosmogenic nuclides, Beryllium 10 and Aluminum 26 (written as 10Be and 26Al). Both 10Be and 26Al occur in rocks that have been exposed to the sun (to read more about cosmogenic nuclides, click here).

A figure from the Shakun et al. paper. Panel A represents a map of Antarctica, with the Transantarctic Mountains represented as triangles. The location of the core used in the study is denoted by a black star. Panel B is a zoomed-in area of East Antarctica (the box in Panel A) showing the directions that ice flows from the continent. Panel C shows what East Antarctica would look like if the ice melted back enough for the location of the drill core to be exposed to sunlight.

Methods: First, the researchers of the study needed to obtain rocks and sediment that was underneath East Antarctica. Lucky for them, there was already drilled cores from this area! In 2006-2007, a team of scientists went to Antarctica for the purpose of recovering sediment cores from beneath the East Antarctic Ice Sheet. The team ended up with two cores that were more than 1,200 meters (0.75 miles) in length. The project was called ANDRILL, and you can read more about it here. The cores are stored in a special facility, and any scientist that wants material (rocks and sediment) from the cores can request it.

Once the scientists in this study had the sediment and rocks, they cleaned the rocks of the very fine sediment until they had a good amount of rocks, which were mostly quartz. They then used a certain method to extract and measure the amounts of 10Be and 26Al in the rocks. The idea is that with long-term exposure to sunlight, the rocks would contain high amounts of 10Be and 26Al. This would indicate that at the time the rocks were deposited millions of years ago, the ice on East Antarctica would have to be melted away, and the land surface exposed.

Results: The scientists found little, if any, of 10Be and 26Al in their samples. This indicates that the rocks were not exposed to sunlight, and thus the glacier that covers East Antarctica did not melt back and expose the land surface millions of years ago.

Why is this study important? This study used a novel approach and really cool method to investigate a problem that scientists didn’t agree upon. It also indicates, to some degree, how much the glacier on East Antarctica melted during interglacial (warm periods within an ice age) times over the last millions of years.

Citation:  Shakun, J. D., Corbett, L. B.,  Bierman, P. R., Underwood, K., Rizzo, D. M.,  Zimmerman, S. R., Caffee, M. W., Naish, T., Golledge, N. R., Hay, C. C. 2018. Minimal East Antarctic Ice Sheet retreat onto land  during the past eight million years. Nature. doi:10.1038/s41586-018-0155-6

Ron Fine, Citizen Scientist

The picture that appeared on the front page of the Cincinnati Enquirer in April, 2012, presenting “Godzillus” to the public with Prof. Carlton Brett (center) and Prof. David Meyer (right).

What is your favorite part about being a scientist, and how did you become interested in science?

From my earliest memories I have always had an interest in dinosaurs and fossils. I grew up in Bellbrook, Ohio, where I spent many a day playing in the creeks in Magee Park and the Sugarcreek Reserve. Both were loaded with fossils from the famous Cincinnatian series of the Ordovician. While collecting fossils is my absolute favorite, I’ve always been fascinated by science and nature in general, with interests in biology, geology, minerals, astronomy, engineering and physics, as well as art, cooking and photography.

What do you do?

I have a degree in Landscape Architecture, but I work as a mechanical designer in the aerospace industry. Currently, I design tools that are used to build jet engines. I create the 3D models and drawings, which are used to make the tools.

While I haven’t as yet spent much time doing my own research, I’ve been blessed to help the professionals with numerous papers based on specimens I collected. I love and collect all fossils, so I’ve not concentrated on any particular group or type. I feel this has been advantageous, as it gives me more opportunities to work with the various scientists who do have areas of specialty. Lately, I’ve been working with Dr. Alycia Stigall on brachiopods. In the past I worked with Dr. Roger Cuffey on bryozoans, and Dr.’s Carlton Brett and David Meyer on Godzillus. As a member of the Dry Dredgers, the oldest fossil club in North America, I get to contribute regularly. I take meeting photos for the website, bring in specimens for others to examine, and occasionally write something for the newsletter or website. I also volunteer, and am an exhibitor, at Geofair every year, and occasionally play fossil tour guide at local parks or give presentations with my portable fossil display.

Playing fossil field guide to teacher Brian Dempsey and fifteen students from Acton-Boxborough Regional High School, in Acton, MA, at Caesar Creek State Park in Waynesville, Ohio in May, 2017.

How does your research contribute to the understanding of climate change, evolution, or to the betterment of society in general?

I have a talent for finding rare, unusual or exceptional fossils. I bring these specimens to the attention of the professionals so that they can be properly studied, and sometimes, they are used to write a scientific paper and are deposited in a museum or university collection for future scientists to study. Godzillus has been my best effort so far. It actually became very famous! I collect everything prodigiously. The quality specimens are made available to professionals for research projects, and the rest is given to the Dry Dredgers to make the fossil kits that fund club activities, or given to school kids.

What advice do you have for aspiring scientists?

Your life will be far richer if you pursue your interests. Find others who share your passions, join a club, volunteer. You won’t regret it!