This week’s Fossil Friday feature is a fossil ark shell called Anadara (Rasia) dariensis. This clam was found stuck to rocks in the Early and Late Miocene (21-8 mya) waters around Panama in both the Caribbean and the Pacific.Their tiny teeth are arranged in a straight line along the hinge line on the inside of the shell. This type of dentition is called “taxodont.”
Read the “Fossils of Panama” page on this mollusc here.
This week’s Fossil Friday post showcases a hammerhead (Sphyrna sp.) shark tooth. This particular specimen is from the Milwhite Gunn Farm Mine site in Florida, but fossil hammerhead teeth have been found in the Gatún Formation in Las Lomas and the Chucunaque Formation in Lago Bayano. Hammerhead sharks are found worldwide today but are only found in the Caribbean in the fossil record.
To learn more about fossil hammerhead sharks from Panama, check out the “Fossils of Panama” page on hammerhead shark teeth here.
A few weeks ago, when we were driving to one of our dig sites, we noticed a dip in the road that hadn’t been there the previous week. When we returned to the site the next week the dip was lower by at least six inches. The following week I decided driving down that road was not in our best interest but we wanted to investigate. We were able to document cracks and fissures that were several feet long and 4-12 inches wide. The next week there were men surveying the area and the week after that there were excavators and backhoes. I had read about the massive landslides during the construction of the canal and was aware that due to the geology of the area they are an ongoing problem. It was fascinating and I have to admit a bit disconcerting to watch the progression of the landslide and the remedial measures that were taken in response. I was so intrigued I did a little bit of research.
Landslides have always been a problem in the Panama Canal, most notably in the 13-km long section at the southern end of the canal known as the Culebra Cut (also known as Gaillard Cut). The special wonder of the canal is Culebra Cut. It cuts through the continental divide and is the high, hard rock basaltic slopes and the lower, soft shale/clay slopes of the Cucaracha and Culebra Formations that can be seen in picturesque photos of the canal. All the rain and humidity softens the shale into mud and clay. The instability of the mud and clay results in continual landslides. David McCullough in “Path Between The Seas”, his famous book about the building of the Panama Canal, states that all technical problems were small compared to the slides in the cut. Workers on the canal would arrive in the morning and months of digging, as well as equipment, would be completely wiped out by thousands of cubic yards of dirt and rock from slides. The massive slides in the cut also played a big part in the French Canal Company’s inability to complete the canal.
In 1915 the second year of operation, the canal was hit with two major landslides that struck simultaneously. Both the east side and west side of the Culebra Formation slid, resulting in the closure of the canal for seven months. In 1986 a geotechnical advisory board was formed after a major reactivation of the East Cucaracha slide encroached into the navigational channel of the canal and caused a closure of twelve hours.
In 1988 a report was issued by Luis D. Alfaro on the risk of landslides in Gaillard Cut. He researched all of the slide events that were documented up to 1986, thirty-one in all. In his report he suggests dividing the cut into zones of relative uniform geological environments to help monitor and document movement. We use these zone names at our dig sites. Today the slopes are monitored constantly through instrumentation and field inspections so remedial measures can be implemented if movement is detected.
The good news for us is that there is now a newly scraped-clean excavation site for us to investigate for fossils. We went there twice last week and discovered shark teeth, croc teeth, and a bunch of invertebrate fossils.
This week’s Fossil Friday features an astragalus of the camel Aguascalientia panamaensis. You can easily tell that these and other camels are artiodactyls (even-toed ungulates) from their double pulley astragalus. This specimen was found at the Lirio Norte site of the Las Cascadas Formation and is early Miocene in age.
This week’s Fossil Friday post features the turrid snail Hindsiclava consors (Family Turridae). H. consors would have been found in both on the Caribbean and the Pacific sides of Panama from the early Miocene to the late Pliocene. This specimen was found by Gary Morgan in the Gatún Formation and is late Miocene in age.
This family of predatory snails is known to prey primarily on polychaete worms (Phylum Annelida, Class Polychaeta). One modern-day polychaete worm is the Christmas tree worm, which uses its Christmas tree-shaped appendages for respiration and for filter feeding.
To learn more about this turrid snail, see the “Fossils of Panama” post on it here.
This week’s Fossil Friday is the mandible of the camel Aguascalientia minuta. This specimen was found at the Lirio Norte Graben site in the Las Cascadas Formation and is early Miocene in age. This fossil camel species is the smallest known floridatraguline (Family Floridatragulinae).
To learn more about this specimen, read the publication on it here. Also, be sure to check out another floridatraguline from Panama (Aguascalientia panamaensis) at one of our previous Fossil Friday posts here.
Rincon, A., Bloch, J.I., Suarez, C., MacFadden, B.J., and Jaramillo, C. 2012 New Floridatragulines (Mammalia, Camelidae) From The Early Miocene Las Cascadas Formation, Panama. Journal of Vertebrate Paleontology, 32: 456-475. www.dx.doi.org/10.1080/02724634.2012.635736
Last month some visitors from the States and I had the opportunity to take a three hour guided tour of Barro Colorado Island. One of my friends noted that you should always be Leery of a three hour tour to an island after the fate of the Skipper and Gilligan. But we decided to brave it anyway.
The island was established as a biological reserve in 1923 and has been administered by the Smithsonian since 1946. It is part of the Barro Colorado Nature Monument that includes five surrounding peninsulas and encompasses 12,000 acres. Every year hundreds of scientists come to Panama to do research at the Smithsonian Tropical Research Center on the island.
The island is located in the middle of Lake Gatun, a man-made lake formed when they dammed the Chagres river to build the Panama Canal. The tropical forest on the island is home to a diverse population of wildlife including over 120 species of mammals.
The tour began with an hour long boat ride along the canal to the dock at Barro Colorado. It was fascinating to sail alongside the big ships that were traversing the canal route. My friend is a merchant marine and was able to educate us about the types of ships we were passing and what they might carrying.
We headed out for our hike through the forest. Along the way we were introduced to incredible flora and fauna. We saw roosting fruit bats, eggs of the red eye tree frog, foam nest of the tungara frog, a coati, walking trees, howler monkeys, poisonous caterpillars, a tinamou (a turkey like bird), spiders dining on something deli, leaf cutter ants, and agoutis along with many more amazing plants and animals.
Red eye tree frog eggs
Roosting fruit bats
Leaf cutter ants
Back to the dock Barro Colorado
We finished up with a buffet lunch of fish and rice, and a boat ride back to the dock in Gamboa, tired, happy and full of great food! If you get a chance to go on this tour I give it two thumbs up! (All photos by Sara ElShafie)
Welcome to the first Fossil Friday post of 2016! This week we have an exciting specimen to present: a partial skull of the protoceratid Paratoceras coatesi. This specimen is the holotype of the species and was found in the Escobar Section locality of the Cucaracha Formation (early Miocene).
This week’s Fossil Friday feature is the tooth of an extinct species of shark called Physogaleus contortus. This specimen was found in the Las Cascadas locality of the Culebra Formation and is early Miocene in age. This shark had a widespread distribution during the middle Miocene.
To learn more about this specimen, read the publication that includes it here.
Pimiento C., Gonzalez G., Hendy A., Jaramillo C., MacFadden B.J., Montes C., Suarez S.C., Shippritt M. 2013. Early Miocene chondrichthyans from the Culebra Formation, Panama: A window into marine vertebrate faunas before closure of the Central American Seaway. Journal of South American Earth Sciences 42: 159-170 www.dx.doi.org/10.1016/j.jsames.2012.11.005.
This week’s Fossil Friday is the Springvale cup and saucer limpet, Crucibulum springvaleense. This specimen was collected from the Gatún Formation and the mollusc that inhabited it would have been found filter-feeding while attached to rocks in Late Miocene oceans. Although this mollusc looks similar to a limpet, it is not a true limpet and is not closely related.