“En la casa…” 7/24/2015
We began the morning at 7:45 am with a discussion led by Dr. Jonathan Hendricks on the assigned reading “Spatial and Stratigraphic Variation of Marine Paleoenvironments in the Middle-Upper Miocene Gatun Formation, Isthmus of Panama” by Austin J. W. Hendy. The article was about the Gatun Formation. The Gatun Formation is a geologic formation that preserves fossils dating back to the Neogene period. The formation was formed approximately 10 millions years ago, and is one of the most diverse marine fossil localities representing nearly 200 species.
The discussion began by clarifying the main ideas of the article:
- Mollusks species are depth dependent.
- Organisms found in the formation were less diverse near the shore.
- Lowest layers (oldest) are most fossiliferous.
- Just a handful of species seems to be the most common.
Hendy was able to assign depths in the Gatun Formation by looking at the mollusks present in the rock. He used a method known as “Taxonomic Uniformitarianism”. Uniformitarianism means “present is the key to the past”. This method uses modern day species to interpret the environments of prehistoric species. It assumes that the environmental requirements of the fossils were the same as those of the most closely related living representatives.
The paper was very dense for the teachers. We struggled through the vocabulary and realized quickly there was a science to reading scientific papers. Although the paper was difficult, it was so helpful to read an article about the history of the locality that we were about to visit as well as get an idea of the diversity and type of fossils we were destined to see.
The discussion ended around 8:30 am and we were immediately on the way to the Gatun Formation. In just over an hour, we arrived at our locality. The Gatun Formation was adjacent to a small neighborhood in an area called San Judas. The substrate was a fine black particle with littered with white specks. Each white speck was a 10 million old fossil! At first glance, there was no doubt that the most abundant fossil was the Turritella.
The rock quarry also had a great example of a normal fault. A fault is a geologic term for which areas of land are being pulled apart. The tension in the crust increases until the rock fractures. As a result, one block of land moves downward in relation to the block of land on the other side of the fault.
We collected for a total of three hours. We found shark teeth, a shark vertebrae, a wonderfully preserved crab, bivalves, Crucibulum, Turritella, corals, scallops, a few cowries, cone shells, olive shells and so much more!
We left San Judas at 1:00 pm and drove to the Miraflores Locks Visitor Center on the Panama Canal. The Miraflores locks were incredible! The museum taught visitors about the past, present and future of this engineering marvel that has had such an impact on International trade. And we were lucky enough to catch a ship in transit and see the lock gates open, the mules at work, and the water levels changing. We left the locks at 3:45 pm and went to a second locality called Sabanitas.
We arrived at Sabanitas at 4:00 pm and only had 30 minutes to explore. Sabanitas is another fossil locality that is well documented in the literature. It has a very similar substrate and diversity as the rock quarry in San Judas. We found similar fossils, however, they seemed to be smaller in size. This locality was also abundant in Turritellas. Near the Sabanitas locality, there was what looked like a storage unit. It was in fact a “Push Button” called Las Lomas Suites. Push Button Hotels seem to be a thing all over Latin America. It is a discrete hotel that you can rent by the hour.
After Sabanitas, we went back to the hotel to clean up before the poolside chat. We met at 5:30 pm on the pool deck to reflect on the day and compare our findings at the two localities.
Dr. Hendricks began by describing the diversity of the cone shell populations. The team collected roughly 8-10 different species of cone shells. They were smaller than expected but had similar diversity as seen in Florida. The cone shell collection ranged in sizes. The larger cone shells were found on the ground level of the quarry. This possibly indicates different paleodepths of the Gatun Formation because larger species are representative of shallower depths. We did not see many predation marks on the shells either.
Victor was satisfied with the shark teeth collection as well. The team collected about three-dozen teeth and a shark vertebra. The teeth represented about six different species of sharks.
The shell collections each teacher collected at these sites will be able to brought back to the classroom for use. It will be interesting to see what we all collected at the washing. Would our collection represent the site? Did we tend to collect larger shells and leave the smaller ones?
After the poolside side, which ended around 7:00 pm. We all got cabs to go to Mercado de Mariscos in Casco Viejo. Unfortunately, the actual market for fresh fish was closed by then, the restaurants remained opened. The group met at the Mariners and enjoyed $1.50 ceviche! It was a great place filled with locals and their families. The waiter surprised the group with an “en la casa” dish that resembled fried chicken. As many of us dug in, we found out that they were fish innards, which included fried fish hearts, livers, and ovaries! Panama has its own unique and rich cuisine but so far we have had a wonderful Panamanian food experience.