A Brief Paleohistory of Panamá

(en español)

Overlooking view of the canal from Zion Hill. Puente Centenario is visible in the distance.

As we have heard, the visiting group from the University of Florida just got back from a visit to Panamá, during which much time was spent in the canal searching for fossils.  The museum interns got their first taste of the Panamá sun! The trip went well, and many fossils were successfully uncovered.

In addition to fossil hunting, we were all able to visit the BioMuseo last week.  While there, we learned a little more about the geologic history of Panamá.  I enjoyed hearing more about the context of this important field area very much.  After all, these fossils that we so desperately search for are part of a larger story, which I would like to talk briefly about today: the paleohistory of Panamá and the great implications of the closing of the isthmus.

The exhibit at the BioMuseo started at the very beginning, a very good place to start…

Before Panamá was a solid land mass, the area was made up of a volcanic arc, in form of underwater volcanoes caused by tectonic subduction.  Pillow basalts, being the oldest rock found in Panamá, mark the beginning of this point in the paleohistory.  A series of volcanic and plutonic rocks formed during this whole process.  These underwater volcanoes eventually grew into small surfaced islands as they were uplifted.  This began the process of sedimentation on top of the complex crystalline basement.

There is much debate on exactly when and how the narrow seaway connecting the Pacific Ocean and Caribbean Sea closed.  However, it is widely accepted that this closing had a massive effect on global climate and fauna.  This connection between the Americas caused a massive biotic interchange between continents.  In addition, global circulation patterns changed, which caused northern hemisphere glaciation.   The change in global thermohaline circulation due to the closing of this narrow seaway also had a major impact on the evolution of humans, and might have been the catalyst for humans to develop into a bipedal species.

Posing with some prehistoric animals at the BioMuseo.           [L-R: Sonia, Sophie, Adam]

In closing, while at the BioMuseo, we made a contact who would like for us to help make a narrative talking about the paleohistory of Panamá from a geologic standpoint.  In addition, we might try and organize workshops or even field trips to the canal for museum visitors.  The goal would be to present a more understandable, detailed, and interesting geologic account of the region.  As this is a more obscure and difficult topic, they would like our help to get people interested in it.  The four of us are very excited, as much of our training has been in geology.  We will keep you updated on this process!

Thanks and, of course, Go Gators.

~Sonia~

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References:

– BioMuseo, Panamá

– Montes, C. et al. Arc-continent collision and orocline formation: Closing of the Central American seaway. J. Geophys. Res. Solid Earth 1978–2012 117, (2012).

 

Fossil Friday 3/13/2015: A fossil shark tooth

UF 242872, the tip of an upper tooth of Hemipristis serra. (Photo © VP FLMNH).

This Fossil Friday I would like to show you another shark from the Culebra Formation called Hemipristis serra. This specimen was found at the Hodge’s Hill site and is from the early Miocene. Fossils of this extinct shark are most common in warm-water marine deposits. Hemipristis elongatus, also known as the snaggletooth shark, is the only extant member of the genus and is found in tropical marine settings. Members of the genus Hemipristis are just a few of many that belong to the chondrichthyan Order Carcharhiniformes. Modern carcharhiniform sharks can be found in waters worldwide ranging from arctic to tropical and near shore to deep water.

To read more about this specimen, read the publication on it here. To read an entry in Fossils of Panama on Hemipristis serra from the Gatún Formation, click here.

Cleaning up after spring break

And we’re back! A ton has happened since our last post. A huge group of our scientific partners at the University of Florida spent a week helping us collect fossils in Panamá. It was a wild time, with many folks downing Gatorades to stay hydrated in the blazing afternoon sun. Our combined efforts led to many fossil finds!

Jeremy with his humerus at Centenario 2 of the Cucaracha Formation

Anyhow, we are picking up where we left off. Last time, I described the heavy lifting we did to clean off one of our fossil localities and increase productivity. After we moved all of that sediment, Jeremy found the distal end of a humerus, possible from a fossil rhinoceros! We’ve continued down this path, moving to a new exposure of the Cucaracha Formation.

We just finished up a two-day project to revive our Centenario 6 locality – a fossil collection site where previous researchers have found unique fossils crucial to our understanding of American biogeography. The effort was literally massive. We must have busted up and shoveled nearly one thousand pounds of rocks and sediments with our rock hammers and pickaxes.

When we started…

In order to continue finding fossils, you have to work to expose layers where bones are most-concentrated – a result of the environmental conditions where the sediment was being laid down millions of years ago.  This unit (Cucaracha, ~19 Ma) has produced incredible finds, including part of a jaw from a “bear-dog“ This a carnivorous mammal that originated in the “Old World”, and an Antracothere, which is an artiodactyl ungulate closely related to hippos and which is a sister taxa of whales. These fossils are critical clues, not only because fossil carnivores from this period are incredibly rare, but also because both of these fossils strongly link the mammals living in Panamá during the Miocene to those living contemporaneously in North America. The more evidence we find, the better our picture of Panamá and its role in the relationship between North and South America before the closure of the isthmus. Also, we’re looking to find some monkeys to better complete the picture.

Our newly restored locality!

Stay tuned for more! And Go Gators!

Making Maps in R

This past week was a busy one in the field, due to all those who joined us during University of Florida’s spring break. So many exciting fossil finds! Lots of long, hot, sticky days too, of course. We’re still going out into the field each day, but perhaps now’s the time to take a quick mental break from the heat and write about something we did a few weeks ago, in an air-conditioned room at STRI’s Tupper facility with coffee and pastries provided. We attended a three-day course on GIS and mapping with R given by Richard Condit, a STRI staff scientist. R is a programming language used for statistics and graphics that has been gaining popularity within the scientific community recently because it’s open source, there are ample online forums discussing how to do anything under the sun with R, and it’s very transparent, which is important for ensuring that experiments are repeatable.We prepared for the course a little bit beforehand as it was the first foray into R for all of us, but it was startling how quickly we were able to advance under Dr. Condit’s guidance. Within the first day we were using GIS data to create visual maps of Panama and the world. By day three, we had created our own features (I made a polygon representing Cerro Ancon, where we live), learned to add attributes to features, and were working with rasters. It isn’t hard to imagine situations where knowing how to work with spatial data in R would come in handy; some of our classmates were already applying what they had learned to their own research. Hopefully we will have the chance to learn more about R, perhaps by mapping some of our localities.

Go Gators!

Panama!

…Aaand we’re back!

PCP-PIRE intern Justy Alicea ready to be lifted to the jungle canopy.

After over a week in Panama, we are back in Gainesville, a little tanner and a little wiser. We learned a great deal on this trip and had a great time along the way. We were up at sunrise, worked as giant freighters passed up and down the canal all day and got to know Panama City and each other a little better.

The peaceful Sloth. One of the many locals encountered on our trip.

We traveled all day Saturday, but we officially started the trip off on Sunday with a tour of the jungle canopy, where we saw iguanas,  monkeys and sloths, the group favorite. They were incredibly cute. We all wholeheartedly agreed we needed sloths in our lives. We then went to Punta Culebra, where we were able to get up close with local starfish, sea turtles, pelicans and rays.

The week itself was all work. We woke up and got ready to meet at 630 for breakfast, piled into a taxi van to the Smithsonian Tropical Research Institute (STRI) by 7, gathered equipment and field trucks, and drove to the canal. We were out in the field by 9. We’d spend all day digging, taking lunch around 12 and back at it until 3. Then we’d all jump back in the trucks covered in dirt and sweat and drive back to STRI to drop off our equipment, jump back in the taxi van, and be back at the hotel by 430. We’d all go shower and meet back up by 630 for dinner, where we’d go as a big group or break off into smaller groups depending on food preferences.  We hung out together after dinner and then be in bed in time to do it all over again the next day.

Shrimp claw. You can just make out the pincers on the left side.

We found a lot of really nice fossils throughout the various localities we worked, from plants to sharks to horses and rhinos. It was intense, often heavy work. By noon the temperature was in the 80s-90s and if there was no breeze or cloud cover along the canal, fatigue set in quick. I almost learned the hard way that not even water is enough for dealing with that kind of heat and we kept electrolytic drinks handy at all times.

Some of the PCP-PIRE Spring break cohort in action.

We ended the trip with a visit to the newly opened BioMuseo on Friday and a walk around the old Spanish ruins of Casco Viejo on Saturday. The small, modern museum was great. Highly interactive, artistic and informative, the museum had some well designed halls. The “Panama-rama” and the great biotic interchange halls were especially impressive and they left a sense of wonder and drama about the impact of this thin stretch of land connecting 2 continents on the world. It perfectly summed up the mark this trip left on all of us.

Adventures in Panama!!

Dawn, Justy, Me, Andrea, and Will

It’s been a little more than a week since my last blog, and boy a lot has happened… Last week I and another 14 participants from the Florida Museum of Natural History visited Panama for spring break. Our goal was to extract fossils from the canal and gain experience in the field.

Sunday, March 1

Our first day in Panama we woke up early to visit the tropical canopy of Parque Natural Metropolitano, and use the crane access system to propel us towards the canopy of the trees. Nathan, Chris, Victor, Mike, and I were the first to ascend; at the tree top we could see in the far distance the whole of Panama City, we saw the never ending race of the skyscrapers reaching towards the heavens. We also saw a sloth peacefully sleeping in the branches, a flock of toucans flying as the wind, and beautiful blossoms covering the canopy. When we reached the ground we went for a hike and saw howler monkeys playfully jumping from branch to branch in the tropical forest.  We ended the day at Punta Culebra where we saw the sunset in the Pacific.

Monday, March 2

We spent most of Monday’s morning at the offices of STRI filling out paper work for our access to the canal as well as transportation. During the afternoon we headed towards the canal where we met the field interns (Jeremy, Sophie, Adam and Sonia) and their mentor Jorge, who gave us a tour to the different excavation site. We started at the Centenario Bridge then move to the Las Cascadas Formation. At the Las Cascadas Formation I followed Nathan and Chris towards the fossilized leaf deposits while the others stayed at the bottom layers looking for vertebrate remains. At the leaf site the outcrop was divided in a top layer of oxidized sediments and a bottom grayish layer. Nathan tells us that that last time he visited the site he had found fossilized leaves in the oxidized layers.  So I sit and commence to excavate with him, but the outcrop crumbles in my hands and I don’t seem to find anything. After a while I decide to excavate in the grayish layer just for curiosity, so I grab my hammer, hit the outcrop with all my strength and take out a big block, when I flip it I discovered the most beautifully preserved leaf. In my excitement I show it to Nathan and he practically starts jumping with joy on one leg!  We then visited the Empire site looking for some crabs. At this locality we had to be aware of our surrounding because it was being worked with bulldozers extracting sediments. It made it difficult for us to extract fossils with all the dust in the air that would get stuck in our eyes, but that still didn’t stop us for making great findings. We ended the day at Hodges Hill collecting fossilized wood.

Tuesday, March 3

Chris, Nathan, Roger, Will, Cristina, and I went back to the Las Cascadas Formation to the leaf site. Roger, Will and Cristina were looking for arthropods; Nathan, Chris and I were looking for botanical fossilized remains, and we spent most of the day there digging a quarry.

Wednesday, March 4

For the first half of the day I was with Nathan and Chris collecting fossilized wood in Hodges Hill. We found a large trunk and some crabs. In the afternoon Victor and I were sent to the Las Cascadas Formation to dig up some vertebrate fossils while Roger, Nathan, Chris, Cristina and Jorge went to the east side of the canal to explore the new sites containing fossilized crabs and leaves. Once I was in the Las Cascadas Formation all I could find was fossilized roots, so every time I would call John  to check what I had found he would say it was a root. After I had gotten tired of the spot I was given to excavate I decided to move towards the shale. At first all I could find was matrix when suddenly I come across something shiny, I called out for Jon saying “Jon I found something!!” He tells me “What is it?” I respond “I don’t know”. Jon sends Aldo to check what I had, after a while of Aldo looking at it Jon asks “Well, what is it?” Aldo responds “I think you might need to look at this” Jon practically came running towards us to see what we had. To make a long story short there are three possibilities of what my findings are. Jon and Aldo strongly believe it might be a horse tooth but we won’t know for sure until the whole tooth has been cleared from the surrounding matrix…. I knew I had found something.

Thursday, March 5

This time I went with the group from the day before to the east side of the canal. After the previous day of exploring the site Nathan had an idea of where the fossilized leaves and fruits might be, so Nathan, Chris, Jorge, Sonia and I started exploring the jungle of elephant grass, it was so high and thick that we could barely move through it. We had to use our hammer or throw ourselves in the grass to lower it down and make a path; we couldn’t use a machete because we had left it at the west side of the canal so we had to manage with what we had… made me feel like if we were in an episode of Man vs. Wild! After walking through the grass we finally found the site.

Friday, March 6

Cristina, Sophie, Nathan, Chris and I tried to enter the east side of the canal again but our permit had expired so we had to return to the west side of the canal. We notified the others of our group and made an exchange of people, Chris for Jeremy. So Jeremy, Nathan, Cristina and I went to Empire site to find some fruits, we spend half of the day there and found plenty of seeds. During the late afternoon we visited the Biomuseo.

Saturday, March 7

We renewed our permits and spent the day at the east side of the canal digging a quarry for the new leaf site and collecting good samples. At the end of the day Nathan, Justy and I went to Casco Viejo and explored Panama City. We had a great time on our last day in Panama.

Visiting Panama has been an extraordinary experience filled with new adventures, experience and culture. Plus, now that we have collected so many fossilized leaves I can try to identify them and compare them to the ones of Tennessee. Also, we can make a booklet of the collected leaves for when we return to Panama so that we can find them again in the field and can easily know which leaf was discovered.

Until next time!

Update: Spring Break in Panama

The members of PCP PIRE that traveled to Panama for Spring Break have been collaborating with the field interns to collect plant, invertebrate and vertebrate fossils in several localities, both old and new. On Friday the group left the field early to visit the Biomuseo, a museum that focuses on the history and biodiversity of Panama. PCP PIRE, STRI and several other institutions have made contributions to the museum and it was the first time that many members of the Spring Break crew had seen the museum since its construction phase. The museum includes permanent and temporary galleries that explain the history of Panama: its geologic history and how the Isthmus came to be, its evolutionary history and biodiversity, and its cultural history and how humans have shaped the landscape of Panama. One temporary exhibit centered on contributions made by PCP PIRE and other institutions and included details of our discoveries so far as well as paleoart and casts of fossils made by members of the project. It was an amazing experience to visit the museum and see what we have discovered through the course of this project and how we are sharing our discoveries with the public.

The Spring Break crew listen to a tour guide explain the details of the architecture of the Biomuseo. Photo © Dawn Mitchell.

The Spring Break crew discuss the geology of the Isthmus of Panama as they walk through the “Building the Bridge” exhibit, which narrates the geological history of Panama. Photo  © Dawn Mitchell.

Members of the PCP PIRE Spring Break crew explore the “Worlds Collide” exhibit at the Biomuseo. The exhibit includes life-size statues of animals clashing in a representation of the Great American Biotic Interchange after the Isthmus of Panama was fully formed. Photo © Dawn Mitchell.

The Spring Break group is wrapping up their fieldwork on Saturday and will be headed back to Florida on Sunday. Be sure to check back next week to hear from our museum interns about their experience in the field!

Fossil Friday 3/6/15: A jewel box clam

UF 220128, the right valve of the clam Chama berjadinensis. The two shiny impressions on the left and right sides of the inside of the valve are the adductor muscle scars. These muscles are used to pull the valves together and close the shell. (Photo © IVP FLMNH)

For this Fossil Friday, we have the right valve of a jewel box clam called Chama berjadinensis. This specimen is from the Gatún Formation of Panama and is Late Miocene in age. Clams are bivalve molluscs (Class Bivalvia, Phylum Mollusca) and are so named for the two valves that make up their shell. The outside of the valves of Chama berjadinensis can have irregular or even frilly growth lines radiating out from the umbo (usually the highest point on the valve, near the hinge line) that run parallel to the shell margin.

To find out more about this specimen, read the Fossils of Panama page on Chama berjadinensis from the Gatún Formation here.

Spring Break in Panama

Photo of the Spring Break Panama Canal participants at the Canopy Crane.

This week 15 additional people descended on the Panama Canal – the University of Florida Spring Break crew has arrived. For the majority of participants, this is their first experience in Panama.  We arrived Saturday afternoon and took Sunday as a tourist day to see the sights – the canopy crane and Punta Culebra were both great activities.

The first group is hooked up to the crane, which lifts them into the tree canopy.

The view from the crane.

This iguana was sunbathing in the treetops.

Vista at Punta Culebra.

Monday morning brought us to the Panama Canal.  We depart our hotel at 7AM, get to the canal around 8:30, and work until 3:30.  Quite a few fossils have been found – lots of new vertebrate, invertebrate, and paleobotanical samples are filling the lab at STRI!

Andrea De Renzis, Victor Perez, and Rachel Narducci search the Empirador Formation for sharks teeth and invertebrate marine fossils.

Dawn Mitchell searches for vertebrate fossils in the Las Cascadas Formation.

Museum Intern Will Tifft takes a swing at a difficult layer of Las Palmas along the Panama Canal.