Fossil Friday 7/31/15: A sundial snail

UF 220857

A lateral (left) and dorsal (right) view of the shell of the sundial snail Architectonica nobilis. Photo © IVP FLMNH.

The subject of this week’s Fossil Friday is the sundial snail Architectonica nobilis. This particular specimen is late Miocene in age and was found by former PCP PIRE Postdoc Austin Hendy in the lower Gatún Formation. This snail’s earliest occurence is in the early Miocene and can still be found in shallow marine waters today. These animals produce planktonic larvae that can travel great distances.

To find out more about this kind of snail, check out the Fossils of Panama page on it here.

Fossil Friday: A camel tooth

UF_FGS_5680

UF/FGS 5680, the lower left first molar (m1) of Floridatragulus dolichanthereus. Left: occlusal surface; right: medial surface (side facing the tongue). Photo © VP FLMNH.

This Fossil Friday, we have a tooth from the camelid Floridatragulus dolichanthereus. This specimen was found by Stanley J. Olsen in 1956 at the early Miocene Thomas Farm locality in Florida. Camelid specimens referred to the genus Floridatragulus have also been found in Panama in the early Miocene Cucaracha Formation. F. dolichanthereus belongs to the same subfamily (Floridatragulinae) as Aguascalientia panamensis, which was featured in a previous Fossil Friday post.

Invertebrate Paleontology in the mid-Miocene: A trip to Lago Alajuela

A visit to Panama City by paleontologists Cristina Robins and Ian Cannon from the University of Florida this past week meant several field days focused on sampling invertebrate fossils. The goal: to obtain a better picture of the diversity of invertebrate communities within the formations in the Panama Canal, and increase collections of crustaceans and mollusks to be studied back at the University of Florida. Most exciting was our visit to a site outside the boundary of the Canal Excavation, to sample from the Alajuela Formation. Pictured below, Lago Alajuela, a man-made lake created along the Chagres River and major reservoir within the Canal watershed.

Invertebrate Paleo. collection team, July 15, 2015. Starting with the back row and moving left to right, Cristina Robins, project coordinator PCP-PIRE; Michael Ziegler, PCP-PIRE Intern; Ian Cannon, University of Florida; Jorge Moreno, PCP-PIRE Field Leader; Gina Roberti, PCP-PIRE Intern, Summer 2015.

Invertebrate Paleo. collection team, July 15, 2015, Lago Alajuela. The terraced shorelines and extremely low lake levels reflect record lows in rainfall during June, the third driest June on record in Panama in the last 100 years. So much exposed shoreline makes for fantastic fossil hunting. Starting with the back row and moving left to right, Cristina Robins, project coordinator PCP-PIRE; Michael Ziegler, PCP-PIRE Intern; Ian Cannon, University of Florida; Jorge Moreno, PCP-PIRE Field Leader; Gina Roberti, PCP-PIRE Intern, Summer 2015.

Continue reading

7/17/15: A peccary tooth

UF236934

UF 236934, the upper left second molar of an indeterminate peccary. (Photo © VP FLMNH)

For this Fossil Friday I would like to present an upper tooth of a peccary (Family Tayassuidae). This specimen was found at El Lirio West in 2008 by Ph.D. student Aldo Rincon and is early Miocene in age. Peccaries have bunodont teeth, one of the two main tooth types attributed to artiodactyls (the other being selenodont). Bunodont teeth are characterized by low, rounded cusps. Human teeth are also bunodont.

Be sure to check out one of our past Fossil Friday posts on the peccary “Cynorca” occidentale here.

Fossil Friday 7/10/15: A flat sand dollar

MellitaTenuis

UF 2425, the test of Mellita tenuis. This specimen was found in Manatee County, Florida and is from the Late Pleistocene. (Photo © IVP FLMNH)

This Fossil Friday I would like to focus on the genus Mellita, a group of flat sand dollars (Class Echinoidea, Order Clypeasteroida). Members of this genus are restricted to the shores of North and South America, however they are found on both the Atlantic and Pacific sides of the continents. Members of Mellita feed by plowing through the surface of sand and collecting food particles. The split that resulted in two extant species of the genus, M. quinquiesperforata and M. notabilis, can be attributed to the closing of the Isthmus of Panama.

To learn more about the current distribution and phylogeography of this genus, read this paper that includes specimens from Panama.

Mellita_longifissa

An extant Mellita longifissa plowing through sand. (Photo © Carolina~commonswik)

Reference: Coppard, S.E., Zigler, K. S., Lessios, H.A. Phylogeography of the sand dollar genus Mellita: Cryptic speciation along the coasts of the Americas. Molecular Phylogenetics and Evolution. (2013). doi:10.1016/j.ympev.2013.05.028

Bedrock Quest: Reflections on Fieldwork in the Azuero Peninsula

Delicate and intricate, the complexity of ecology and climate in the tropics presents a challenge for any scientist wishing to study more closely patterns of the naturaleza. Especially for geologists, accessing the bedrock, the layer of rock that forms the base of the land–underlying all soil and bodies of water–, is especially tricky. Hot and humid weather year round in tropical latitudes makes for incredible biological productivity, and happy microbes breakdown rocks into soils at a startling pace. Thus, to find exposures of rock outcrops that were fresh enough to determine the lithology, or composition, required a bit of effort.

A group of students from the University of the Andes examining an outcrop of basalt in Rio Verdadero.

A group of students from the University of the Andes discuss the orientation and lithology of an outcrop of basalt in Rio Verdadero. Plant growth in the rock’s cracks (fractures and faults) highlights patterns in the orientations of such features. Noting the primary direction and orientation of fractures can give information about regional stresses and tectonic changes.

In Azuero especially, it was difficult to see any bedrock beneath thick layers of red- iron rich tropical soils. The majority of land in the past 60 years has been deforested, and pasture land stretches for miles. Thus, to access the rocks, the majority of our time was spent in rivers, where water carved into the bedrock below.

Tiny sparkling grains of a blue-green metamorphic mineral (most likely epidote) that forms when volcanic basalts are hydrothermally altered. Notice the thin orange layer (perhaps microbial) on the surface, which shows weathering or breakdown of the rock ('meteorizado' in spanish). Oftentimes it requires a rock hammer to break open the rock and see past this superficial rind.

Tiny sparkling grains of a blue-green metamorphic mineral (most likely epidote) that forms when volcanic basalts are hydrothermally altered. Notice the thin orange layer (perhaps microbial) on the surface, which shows weathering or breakdown of the rock (‘meteorizado’ in spanish). Oftentimes it requires a rock hammer to break open the rock and see past this superficial rind.

And so, our group of geologists embarked on a quest to find bedrock exposures in the countryside of rural Panama. Pictured in the foreground PCP-PIRE intern Paris Morgan.

IMG_9997

Together with a group of twenty-plus students from the University of the Andes, de Bogota, Colombia, the Summer 2015 PCP-PIRE intern team shared in a three week mission to map the bedrock geology of western Panama.

A half-day’s drive from the Panama Canal Zone, the Azuero peninsula is comprised of rocks much older than those encountered in the Canal. Our goal was to learn more about the tectonic history of the region, to better inform our understanding of the ‘how’ and ‘why’ of the closure of the Isthmus of Panama.  To do this, we spent each day hiking through rivers and along beaches to access outcrops (‘afloramientos’ in spanish), where we would diligently document (in colored pencils on topographic maps) the rock types we encountered, their orientation and extent. By compiling bits of color day after day, it was possible to draw connections between similar rock types and infer (or, quite literally ‘color-in’) the bedrock geologic map of the south-western portion of the peninsula. Increíble!

Paleontologist Jorge Moreno-Bernal, field leader PCP-PIRE.

Paleontologist Jorge Moreno-Bernal, field leader PCP-PIRE.

Trekking through the rural countryside of Panama, the pursuit of a geologic field mapper is to learn the layout of the land…by foot. This caterpillar and paleontologist both captured in the view, caught moving at a slightly different pace.

 

July 2015. By Gina Roberti, PCP-PIRE Intern.

Fossil Friday 7/3/15: An otolith

otolith

UF 264544, the left otolith of Paralonchurus trinidadensis. (Photo © VP FLMNH)

For this week’s Fossil Friday we have an otolith from a fish called Paralonchurus trinidadensis. This specimen was found at the San Judas site in the lower Gatún Formation and is Late Miocene in age. Otoliths or “earstones” are found in bony fishes and are used for hearing and balance. Otoliths also have growth rings similar to tree rings, allowing researchers to estimate the age of the fish when it died.

References:

Florida Fish and Wildlife Conservation Commission. (1999). Introduction to Aging Fish: What Are Otoliths? http://myfwc.com/research/saltwater/fish/age-growth-lab/aging-fish-otoliths/

Fossil Friday 6/26/15: A predatory snail

UF 232528 Stigmaulax guppiana, a moon snail

UF 232528, the shell of the moon snail Stigmaulax guppiana. The complete drill hole found on this shell shows that it was the victim of another drilling predator, perhaps even another moon snail. (Photo © IVP FLMNH)

For this rendition of Fossil Friday, we have a predatory snail called Stigmaulax guppiana. Continue reading

Tennessee Road trip!

This past weekend June 19-21, 2015 I finally had the chance to visit Dawson Clay Pit at Henry County Tennessee, where the fossilized leaves that I am studying were collected. I was accompanied by Nathan Jud, Terry Lott, Dawn Mitchell and Kefren Arjona. We departed from the Museum at 8:30 am towards Tennessee….

IMG_20150621_100501778_HDR

Well, its a long way from Gainesville, rollin’ north on 75. We pass through the state of Georgia, heading towards Milan, Tennessee. It was a 14 hour drive to reach Dr. Roger Moore’s house whom was kind enough to give us a place to spend the night. He guided us through the Dawson Pit locality, were we spent most of the day on Saturday collecting new specimens for the museum collection. Most of the fossil leaves were collected from a dark colored shale which is part of an oxbow lake deposit interpreted by Dilcher (1973) . We didn’t find any new species from which we didn’t already have in the museum’s collections but we did find leaves with well preserved cuticle which we will analyze under a epifluorescence microscope.OLYMPUS DIGITAL CAMERA

The cuticle shows the cellular or epidermis details of the leaf’s surface. The cuticle is like a waxy layer that prevent excess water loss and it help controls the gas exchange from the leaf to the atmosphere. Studying the cuticle can be very useful for the identification of plant species, since each species has its own epidermal features and pattern IMG_20150620_142501533_HDR We had a great weekend up in Tennessee, now to analyze the cuticle of the leaves and if possible add them to my research manuscript.

References:

Taylor T. N, Taylor E. L., Krings M., 2009, Paleobotany: The biology and evolution of fossil plants, second edition,  USA, 13-15pp

Fossil Friday 6/19/15: A partial caiman skull

UF 244434, the left half of the skull of Culebrasuchus mesoamericanus (Photo copyright VP FLMNH)

UF 244434, the left half of the skull of Culebrasuchus mesoamericanus. This is a left lateral view of the skull, which gives us a look at the animal’s teeth. (Photo © VP FLMNH)

This Fossil Friday we have a caiman (Family Alligatoridae, Subfamily Caimaninae) named Culebrasuchus mesoamericanus. This specimen was found by PCP PIRE Ph.D. student Aldo Rincon on March 13, 2009 at the El Lirio Norte site of the Culebra Formation, making it early Miocene in age. It is the sister taxon to all other caimans, making it the first documented taxon to have diverged in the caiman evolutionary lineage. Because of this, this specimen can help us learn more about the divergence of alligators and caimans.

To learn more about this specimen, read the publication about it here. You can also read an eNewsletter article on other fossil crocodylians from Panama here.

Culebrasuchus mesoamericanus by Danielle Byerly

An artistic rendering of Culebrasuchus mesoamericanus. (Artwork © Danielle Byerley)

References:

Hastings, A., Bloch, J., Jaramillo, C., Rincon, A., MacFadden, B. 2013. Systematics and Biogeography of Crocodylians from the Miocene of Panama. Journal of Vertebrate Paleontology 33: 239-263.
www.dx.doi.org/10.1080/02724634.2012.713814