Fossil Friday 7/31/15: A sundial snail

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, 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, 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.

7/17/15: A peccary tooth

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

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.

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 break down 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 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.

Fossil Friday 7/3/15: An 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/