Studying Panama’s Microfossils

Hello from the lab!

While I spend most of my time in the field looking for new fossils, I also have the opportunity to work on original research while I am working with the PCP-PIRE project. I have previously worked with microfossils, specifically ostracods, so I decided to look at the types of ostracods preserved in the Canal deposits.

In particular, I am looking at the ostracods from the new locality we discovered two weeks ago that is full of gastropods and bivalves. When we returned to the site, I discovered nummulites, which led me to believe that foraminifera and ostracods would be present in the deposit as well. However, these fossils require a microscope to see in detail. I collected four sample bags of sediment from different rock layers in the outcrop, and returned to the lab to process them.


The new invertebrate locality, in which I am searching for microfossils.

Another intern at the Smithsonian Center for Paleoecology and Archaeology, Andrés Ríos, also studies fossil ostracods, and helped me prepare the sediment to view under the microscope. We used a dilution of hydrogen peroxide to disaggregate the rock. Andrés sieved the sediment into different grain sizes and let the sediment dry in the lab’s drying oven.

Under the microscope, I use a small paint brush to sift through the grains to locate ostracod individuals and place them on a microfossil slide. Though I have only just begun going through the sediment samples, I have found several types of ostracods, both juveniles and adults. The following ostracods are from a portion of one sediment sample I collected.

I will continue to comb through my sediment samples in search of ostracods, and then work on identifying all the different genera present in the new outcrop. With this information, we will be able to identify the type of environment in which the locality was deposited–whether it was marine, brackish, or freshwater–as well as its relative age based on the microfossil biostratigraphy. I’m looking forward to learning more about this new site based on these minuscule fossils!

-Dipa Desai


New Fossil Finds at Puente Centenario

This week we had an exciting time in the field, specifically at our site under Puente Centenario. Under the shadow of the bridge and nestled among tall stands of elephant grass lies a locality deposited there some 14 to 17 million years ago. These fluvial deposits contain the remains of Panama’s Miocene animals and plants: The ancient river or stream carried teeth, bones, leaves, and other remnants, then gently buried them in sediment. After millions of years entrapped in the rock, these fossils are exhumed by our field team.

Our first excursion to this site yielded several teeth from crocodiles, fish, and even one carnivore molar.


My field supervisor, Jorge Moreno, suspects this is a carnassial molar. 

Teeth are common finds in the field because they are composed of durable enamel that preserves well over time. The enamel also lends a sheen to the fossil which makes it easy to pick out among the dark pebbles and sediment. The color of the fossil tooth is not white, as it was when the animal was alive. When the tooth gets buried, minerals in the surrounding water infiltrate the porous bone and replace the original material, resulting in a darker color.

As our field day was ending, I brushed around the area where I collected the carnassial molar and found something surprising.


An unknown large bone peeking out from the rock where I discovered the carnivore molar.

We returned the next day to carefully excavate this bone. Not knowing how large this bone was, we systematically removed all the rock above and around it until we approached the bone. To strengthen and stabilize it, Jorge covered the exposed bone in paraloid, a type of thin glue that absorbs into the fossil. Using chisels and brushes, we finally freed the bone from the rock and discovered it to be a large astragalus, or ankle bone.


Jorge identified the astragalus as possibly belonging to a large, early type of horse.

We are excited to send these finds to the University of Florida for further study, and to head back to the field to find more fossils!


-Dipa Desai

Exploring the Panama Canal

Hello from the Panama Canal!

I’ve been in Panama for a little less than two months, but every day we head to the field seems like a new adventure uncovering fossils. We usually head out to the field early in the morning, choose a locality, prospect the area, and we dig until lunch. This past week, however, we deviated from our normal routine to scope out some of the new cuts being made along the Canal, and to see if any looked like promising fossil-bearing localities.


Paris Morgan (left) and Jorge Moreno (right) looking from the east side of the Canal across to the new cuts.


Close up on the freshly exposed rocks on the west side of the Canal.

We explored both sides of the Canal for outcrops, and ended up finding several potential localities based on their lithology. My personal favorite was an invertebrate site full of gastropods, bivalves, oysters, and even small nummulites!


Gastropods found at one of the new localities.

We plan on adding these new sites to our PCP-PIRE database, along with each one’s formation, rock type, and a description of the fossils one can find. Hopefully they will yield new fossils that will augment our understanding of Panama’s paleoenvironment!

-Dipa Desai

Field Training at the University of Florida!

Hi all,

I am the new 2015-2016 PCP-PIRE field intern! A little about me: My name is Dipa Desai, and I came to join the PCP-PIRE project through my interest in paleoclimate science. I arrived in Gainesville last week, and have since been training with the paleobotany, invertebrate paleontology, and vertebrate paleontology departments here at UF.

The technique I’ve been learning are ways to prepare the fossils for research. In the paleobotany lab, I helped Nathan, the resident paleobotany expert and post-doc, to create acetate peels of the cross-sections of calcitic mudstone chock full of fossilized plant material. As you can see, the peel below shows a cross-section of a Parinari fruit pit, similar to a peach pit, as well as several other sections of fossilized wood and seeds.

IMG_20151002_094119_906[1]In the vertebrate paleontology lab, I learned how to prep the fossils as they come back from the field. Similar to a puzzle, I glued broken bone fragments back into complete specimens using B-72, a mild adhesive that is reversible with acetone. I also worked on removing larger bones from the plaster jackets that paleontologists use to protect the fossil en route to the lab. I used acetone to wet the matrix surrounding the bone, and gingerly brushed it off to slowly uncover more of the fossil. This particular fossil is from Thomas Farm locality in Florida, but it still gave me a good sense of how to prepare some the vertebrates I will be excavating out of Panama! IMG_20150929_132640[1]IMG_20151002_092113_508[1]In invertebrate paleontology, I created silicone molds of fossils that were preserved as internal casts. Aly and I created clay dams around the targeted cast, and poured silicone into it and let it set. The following day, we peeled the silicone molds off to reveal a 3D cast of the fossil! Here is an example of one Aly did today:IMG_20151002_095834_470[1]I definitely learned a lot these past two weeks, and I’m excited to take these skills to the field!