Henbelk Hernandez

STRI Intern

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My interests lie in geology and paleoecology, specifically the structure, constitution, behaviour, and evolution of physical processes and how they interact with biology. I am working with Erin Dillon to process fossil and modern reef sediments from the Dominican Republic for her shark dermal denticle project. Through this opportunity, I hope to gain experience in the lab and learn more about microfossils and their application in interpreting environmental change over time, which will assist my future academic studies in paleoecology.


Abhy Verdurmen

Intern (SENACYT, STRI, University of Panama)

DSCF4024I’m a Biology undergraduate student at University of Panama profoundly interested in Marine Biology and paleontology, especially the evolution, adaptation and ecology of coral reefs. I’m working on a project that consists of reconstructing the Caribbean reef fish communities of the past, and my master tools for this research are fish otoliths. Otoliths have distinct shapes that enable us to identify fish families, sometimes even to the level of species and fossil otoliths may help us reconstruct the reef fish community of the Caribbean 7000 years ago (i.e. before human impacts). This information will provide a baseline that will enable us to compare “pristine” with modern reef fish communities.

Jorge Salgado

Post-doc (Now Assistant Professor at Universidad de Los Andes)


My research focuses in the understanding of multiple factors influencing freshwater biodiversity over time. I am interesting in the synergies between the introduction of exotic species, water pollution, hydrological alterations and climate change affecting lake assemblages in the Anthropocene. My work integrates paleolimnological techniques, historical data and contemporary monitoring data in human-impacted tropical lakes to:

  1. Assess how tropical lake communities respond over time (decadal to centennial) to environmental change (e.g. eutrophication, climate change and lake water level alterations).
  2. Determine if dominance of exotic aquatic plants and fish are a direct consequence of competitive exclusion with native species; or whether dominance is an indirect cause from direct negative effects of habitat disturbances on native communities.
  3. Explore if there have been positive impacts from the introduction of exotic species (e.g. carbon sequestration.

Abigail Kelly

STRI Pre-doc fellowDSCN1150 (1)

Abby is working on a project that explores how marine life, specifically molluscs, respond to the differing energy regimes of the Pacific and Caribbean sides of the Isthmus of Panama. The Pacific experiences coastal upwelling and high nutrient availability, corresponding to high productivity, while the Caribbean experiences no upwelling and low productivity. How do marine communities, which share many of the same species, differ between the Caribbean and Pacific sides?


Yamilla Samara

STRI Intern

PhotoI am a student at Keiser University in Nicaragua who will be transferring to FIU this year to pursue a degree in Marine Biology. I am working alongside Erin Dillon helping process fossil and modern sediment samples to find shark denticles and formulate a hypothesis of how shark communities were before humans. This will allow me to explore new areas of marine biology and gain experience doing research. It will also help me understand how fossils can be used to interpret the present.

Erin Dillon

PhD Student UC Santa Barbara and STRI Fellow

Reconstructing shark communities using dermal denticles preserved in reef sediments

What were shark communities like before humans? Ecological surveys and historical records demonstrate significant declines in Caribbean shark populations, yet pre-exploitation baselines are nonexistent. Dermal denticles – tiny, tooth-like scales lining the skin of elasmobranchs – can offer insight into shark communities on reefs. We have found denticles to be beautifully preserved in fossil and modern reef sediments, allowing morphometric analysis and classification. Denticle traits are also closely associated with shark ecology and can paint a picture of shark community composition. Evaluating the relative abundances of different denticle morphotypes in sediment samples across time and space can both supplement existing survey data – using time-averaged modern sediments – and assist in the reconstruction of pre-human shark baselines – using the recent fossil record. This previously unexplored data source may reveal what shark communities looked like prior to the advent of fishing, facilitating exciting and important assessments of the magnitude and ecological consequences of global shark declines and producing more meaningful conservation targets.

Save our seas         ~          Erin’s Website

Mauro Lepore


Quantifying Ecological Changes in Reef-Building Corals over Historical Timescales

Coral reefs are declining worldwide but we do not know what a natural reef should look like because their degradation appears to have begun long beforeLeporeML_portrait_2 scientists began to survey reefs. Focusing on Bocas del Toro, Panama, this project aims to quantify the differences in the ecological structure of reef-building corals from a 7000 year old fossil reef versus a modern reefs. The fossil reef and modern reefs respectively developed before and during the period when human activity has been the dominant influence on climate and the environment. Understanding how reef-building corals have changed over historical timescales can help marine managers to assess the decline of Caribbean reefs relative to their condition before the period during which human activity has been the dominant influence on climate and the environment.


Paola Rachello Dolmen

STRI and Texas A&M Postdoctoral fellow

My research interest are: (1) Relating community structure over broad spatial, environmental and temporal scales; (2) Historical interactions between natural variability, biota and humans; (3) Reconstruct past environmental conditions using stable isotope ratios of modern and fossil mollusc specimens; (4) Design, construct, test and maintain useable databases and web-systems and (5) Marine macro- and micro- gastropod biodiversity and taxonomy.

The diverse temporal time-scales (modern to geological), spatial habitat differences in temperate, tropical and subtropical areas and the complexity of the organisms I have studied in the past (macro and micro gastropods, corals, sponges, crustaceans), provides an excellent bPaola_1ackground to conduct innovative research and integrate macroecology and palaeoecology. Thus, my current research focuses on integrating new and existing geochemical data with paleobiological data from the Panama Paleontology Project (PPP) to resolve the drivers of ecological change and evolutionary turnover in the Caribbean. In collaboration with Dr. Ethan Grossman (Texas A&M) I have built a relational database ‘Tropical Ocean Database’ that will be available  to unite paleoecology, evolutionay, environmental and geochemical datasets to allow broad-scale comparison and analysis of marine ecosystems and their communities through time.

Kristin Bell

Scientific Illustrator


The lab was lucky enough to have the excellent scientific illustrator Kristin Bell.

Kristin worked closely with several members of the team. She tackled the tricky concept of illustrating how Caribbean coral reefs have degraded based upon quantitative data from our research.

She also effectively illustrated how damselfish garden in thickets of staghorn coral, and how the behaviour is preserved in the fossil record

damsel garden.jpg

Previous Lab Alumni


Darlenis Cedeño

yadixa nose painting
Yadixa del Valle

MaríaElizabeth 1
Maria Pinzon Concepcion

Bez nazwy 1 kopia
Magdalena Łukowiak

Marcella Herrera

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Dioselina Vigil

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Alexa Fredston-Herman

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Santosh Jagadeeshan

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Katie Cramer

Catherine Courtier

Cannon and Hynes Bocas jpeg (5 of 24)
Abigail Cannon | Grazing and seagrass ecology (Scripps and STRI fellow)

Formation of the Isthmus of Panama

The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.

pdf of the paper

isthmian pairs

New opportunities in the O’Dea lab

We are looking for three new interns/fellows to join the O’Dea lab. For more information download the flyers here: opportunities in the O’Dea lab

Project 1 (one position). Interoceanic differences in energy flow. Position open now, send CV and cover letter to odeaa@si.edu.

Project 2 (two positions). The ecological, life history and environmental differences between Holocene and modern Caribbean coral reef fish assemblages using fossil otoliths. To apply follow directions on the flyer.

Isthminia panamensis: the 6 million year old marine ‘river’ dolphin

isthminia panamensis SI

Four years ago Panamanian student Dioselina Vigil discovered a fossil in rocks near the small town of Piña. It turned out to be more than a bunch of bones. After careful preparation under the careful guidance of Smithsonian marine mammal paleobiologist Nicholas Pyenson and his team, the amazing fossil skull, replete with most of its teeth, was revealed to be a new genus of ‘river’ dolphin which we named Isthminia panamensis.

Isthminia, now an extinct lineage, is the closest relative of the Amazon river dolphins but was found in rocks that were deposited in open ocean just 6 million years ago. In this context the evolution of the river dolphins’ ecological shift from the sea to river becomes just a little clearer.

We are extremely proud that all aspects of the study are open-access. 3D models are available from the Smithsonian’s X 3D site for anyone to download, print and study. The paper itself is published in the open-access journal PeerJ. We even made all reviews available to read in this increasingly popular model for publication and divulgation. A 3D print of the specimen is on display at the Panama’s Biomuseo, and I even have a 3D print of the fossil in my lab.

Get the article here, play around with the 3D models and print out your own Isthminia panamensis

Teasing apart the drivers of extinction over 500 million years

From colleague and friend Paul Harnik’s Paleolab Blog: “How does environmental change shape the relationships between ecological traits and extinction risk? The fossil record is an invaluable resource for answering such questions. In a paper now available early online in the journal Global Change Biology, my collaborators and I show that over the last 500 million years global environmental and geochemical changes have had remarkably little effect on the relationship between geographic range size and extinction risk among marine mollusks. In other words, clams and snails with small geographic ranges have been at elevated risk of extinction throughout their evolutionary history regardless of broad-scale environmental conditions. In contrast, we found that mollusks that live in (rather than on) sediments on the seafloor tended to be at lower risk during times of warmer climate.”

Paper hereScreen Shot 2015-09-10 at 09.24.55

Natural History of the Isthmus of Panama

Felix Rodriguez and I just published a compendium of papers in Spanish for students and non-scientists in Latin America. The book is called “Historia natural del Istmo de Panama” and features a suite of papers covering different topics from the geology of the Isthmus to the future of fishing along both coasts of Panama. The book will be on sale across the Isthmus. Let me know if you wish to purchase a copy.

My contribution can be downloaded here: Historia natural de los mares panameñosbook-HistoriaNat-mod

When did the Isthmus of Panama form?

Swan Cay, Panama

An Isthmus is a narrow land bridge that joins two larger bodies of land. The world’s most famous isthmus, now split by the Panama Canal, connects the continents of North and South America and cuts the once continuous Tropical American seaway into two.

The question ‘When did the Isthmus of Panama form’ has recently been reinvigorated Continue reading “When did the Isthmus of Panama form?”

Can spicules be used to reconstruct ancient sponge communities?

Anyone that has played with coral reef sand has felt the sharp needles of sponge spicules  in their hands. Spicules are made by sponges (and other animals too, like some ascidians) and are like glass. In fact they are glass, being made of pure silica, and they are used by sponges as defense from chomping fish or to help keep the sponge rigid. They come in an amazing variety of shapes and sizes, and the sands of coral reefs can be filled with billions of spicules.

Sponges are very important for reefs. They filter huge quantities of water keeping things clear and clean, provide important homes for loads of other animals, and they protect reefs from erosion by binding the reef together. But, as with most of life in the Caribbean, sponge communities have started to deteriorate. Since the 1980’s they have become less abundant and less diverse. Without sponges reefs may just wash away.

We wish to explore the historical changes in Caribbean reef sponge communities. When did sponges decline and why? The coring project of the TMHE will be exploring sponge spicules through the last few thousand years in several Caribbean reefs (see here). However, spicules are strange beasts. Some sponges produce millions of spicules, others hardly any or none at all. Spicule shape is highly variable (see image) but is not tightly phylogenetically constrained. That means that some spicule types occur in unrelated groups. What’s more, some sponges have more than one type of spicule, sometimes three or four.

This all makes it extremely difficult to reconstruct the sponge community from a bunch of spicules. In this paper student Magdalena Lukowiak at the Polish Academy of Sciences who had held a short term fellowship at STRI explores the taphonomy of sponge spicules on a Caribbean reef in Bocas del Toro. The relationships between sponge community and spicules found on the sea floor explored in this paper will help us to resolve changes in sponge communities through our cores.

Download the paper by clicking on the image

Continue reading “Can spicules be used to reconstruct ancient sponge communities?”

What drives change in the seas?

What drives major ecological and evolutionary changes in the seas? To explore this question we documented changes in the abundance of different clams in the Caribbean over the past 11 Myr.

The structure of clam communities shifted dramatically with an increase in the abundance of attached epifaunal bivalves and a decrease in infaunal bivalves. This was driven by the proliferation of coral reefs, ultimately caused by the closure of the Isthmus of Panama.

These data provide a classic case of proximate and ultimate drivers of evolutionary change. Jill Leonard-Pingel was lead author. Pdf forthcoming….

Extinctions in ancient and modern seas

In the coming century, life in the ocean will be confronted with a suite of environmental conditions that have no analog in human history. Will marine species adapt or go extinct?

The last two years I have been involved in a dynamic working group called “Determinants of extinction in ancient and modern seas” led by Paul Harnik, Rowan Lockwood and Seth Finnegan and funded by NESCent. The aim of the working group is to use the history of life as preserved in the fossil record to help make better predictions about where life is heading in the future, especially in view of the looming sixth mass extinction.

We have just published our first paper in Trends in Ecology and Evolution. The study compares the patterns, drivers, and biological correlates of marine extinctions in the fossil, historical, and modern records and evaluates how this information can be used to better predict the impact of current and projected future environmental changes on extinction risk in the sea.

Download the pdf of the paper by clicking on the image.


Cenozoic seawater Sr/Ca evolution

Records of seawater chemistry help constrain temporal variations in geochemical processes that impact the global carbon cycle and climate through Earth’s history. Here we reconstruct Cenozoic seawater Sr/Ca using fossil Conus and turritellid gastropods.

Our favored seawater Sr/Ca scenarios point to a significant increase in the proportion of aragonite versus calcite deposition in shelf sediments from the Middle Miocene, coincident with the proliferation of coral reefs. We propose that this occurred at least 10 million years after the seawater Mg/Ca threshold was passed, and was instead aided by declining levels of atmospheric carbon dioxide.

Pdf of the paper available by clicking on these images of cone shells…

image from http://www.coneshell.net

A review of the zooid size MART approach

cup lines

As a PhD student I devised and developed a completely new technique for investigating paleoseasonality. Reconstructions of paleoenvironments often fail to understand the importance of the mean annual range of temperature (MART) in both oceanographic and biological contexts. The new technique, called the ‘zooid size approach’ makes use of the temperature-size rule in colonial bryozoans to estimate MART. The temperature-size rule is a universal phenomenon that states that body size decreases as temperature increases.

At the time, our understanding of the temperature-size rule was rudimentary and it was necessary to develop hypotheses on the mechanisms behind the rule and then test them under controlled culture and natural experiments, before finally applying the approach to fossil bryozoans to estimate MART’s in ancient seas.

The original paper published in 2000 presenting the technique can be downloaded here.

Now 10 years later with my ex-Phd supervisor Beth Okamura we review the approach along with the growing body of work that has since been published on the theme. We consider the general issue of why body size varies with temperature, explore the limitations of the approach and highlight its advantages relative to other proxies for palaeotemperature inferences.

Download the pdf of this new paper by clicking on the image.

What happened at the end of the Cretaceous?

Even genetically identical animals can look very different if they grow and live in different environments. Think ‘you are what you eat’. I make use of this phenomenon to try to reveal changes in environments in the deep past by first understanding what drives change in morphology in the animals in question and then measuring that morphology in fossils through time.

I applied this paradigm to one of the most studied and certainly most discussed events in the history of life on earth. The K-T (Cretaceous-Tertiary) boundary, 65 million years ago and the demise of the non-avian Dinosaurs and a suite of other animals and plants in the seas and on land. I made detailed measures of morphology in a number of fossil bryozoans in a beautiful K-T section of chalk in Denmark.

Rapid and repeated changes in morphology suggest that there were a suite of environmental changes in the last few thousand years just before the K-T boundary.

Although we dont explore the causes of the extinctions, or the ‘smoking gun’, these results are important for a full understanding of the complex changes associated with major extinctions observed to occur around the world. Click on the image for the pdf.


Stevns klint 2

Sex in the Caribbean

Evolutionary success was determined by mode of reproduction in cupuladriid bryozoans: Closure of the Panama Isthmus 3 million years ago led to a rapid reduction in primary productivity across the Caribbean. In response, cupuladriid bryozoans underwent a major transition, with evolutionary winners and losers dictated by how much sex they were having. Click on the image to download the pdf.


Hopping hotspots

Hotspots of high species diversity are a prominent feature of modern global biodiversity patterns. Fossil and molecular evidence is starting to reveal the history of these hotspots. There have been at least three marine biodiversity hotspots during the past 50 million years. They have moved across almost half the globe, with their timing and locations coinciding with major tectonic events. The birth and death of successive hotspots highlights the link between environmental change and biodiversity patterns. The antiquity of the taxa in the modern Indo-Australian Archipelago hotspot emphasizes the role of pre-Pleistocene events in shaping modern diversity patterns. Click on the image for the pdf of the paper.


Form and life habit in cupuladriids

Since the late Mesozoic, several bryozoan groups have occupied unstable soft-sediment habitats by adopting a free-living and motile mode of life. Today, the free-living bryozoans often dominate epibenthic faunal communities in these expansive habitats, yet their biology and ecology remain poorly understood. This study examines their unique mode of life by exploring the relationship between form and function in the free-living Cupuladriidae of tropical America. Click on the image for the pdf of the paper.

Hairy colony coloured

Upwelling in the Tropical Eastern Pacific

Most people think Panama has two seas – the Caribbean and the Pacific. In fact it has three and they are each very distinct. This paper presents detailed hydrological measurements from the two seas along the Pacific coast of Panama: the Gulf of Panama and the Gulf of Chiriqui, and characterizes the environmental differences between them. Click on the image for the pdf of the paper.


Investigating palaeoseasonality

A full understanding of any climate requires an appreciation of the amount of seasonal variation in temperature. This is important not only for present-day climatology but also for investigation of ancient environments. In this paper I present a novel approach to reveal how seasonal an ancient sea was by measuring the amount of variation in zooid size within colonies of fossil cheilostome bryozoans.

Click on the image for the pdf…