The marine fossil explorer

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A fishy

The marine fossil explorer

June 13, 2019

Text by Leila Nilipour, STRI

The Panamanian scientist Carlos De Gracia discovered the largest known marlin fossil, helped improve the classification of these ancient species and now seeks to understand how the fish of millions of years ago reacted to changes in the ocean similar to those we are experiencing today

When Carlos De Gracia began his career as a biology student at the University of Panama in 2004, he was already fascinated by the animals of the past. Since childhood, he dreamed of following in the footsteps of paleontologists he saw unearthing dinosaurs on television. But being on the isthmus, and surrounded by oceans, he started working with marine animals, from 1.6 and 3-million years ago, for his undergraduate thesis. Particularly, petrified mollusks.

Fifteen years later, the young Panamanian scientist continues to study ancient marine organisms, but based on his experiences in the field he was attracted to another group of species, the Istiophoridae, those fish with a spear-like bill, known as marlins. Perhaps as a child he did not imagine that, with the support of STRI and Panama’s National Secretariat of Science, Technology and Innovation (Senacyt), he would explore the more than 40 kilometers of coast in Costa Abajo de Colón for two years of expeditions, chasing after fossils.

During those trips, scrutinizing the rocks of the ‘Chagres Formation’, he found small fossilized bones. Using maps and his intuition, he began tracking them until he found a deposit rich in marine fossils, one of a kind for Central America. There, he discovered the largest and best-preserved marlin fossil known, embedded in sediments more than 6 million years old.

These fish would become the focus of his master's degree in geobiology at Charles University in the Czech Republic. Carlos wanted to describe the species of a fossil that he found during his explorations in Colon, but none of the 12 modern species coincided, so he began to compare it with the known fossil species; that is, species of marlin that existed in the past and are now extinct.

While in Europe, he was able to visit museum collections in Brussels and Paris that contained the fossilized bills of six ancient species. As the most resistant part of its body, the bill is usually the best preserved, so researchers rely on bill characteristics to differentiate one species from another.

Soon, Carlos realized that his fossil did not match any of the others. It was a new species. During the process of studying it, Carlos bumped into a problem: few extinct species of marlin had clear descriptions.

“Traditionally, classifying these fish fossils is considered very complicated and is a challenge. When you start to examine them, their bills look practically the same. [The classification system] seemed very ambiguous to me,” Carlos explains.

With this concern in mind, he set out to incorporate a statistical method that allowed him to differentiate the species quantitatively. Harry Fierstine, a retired scientist that devoted his life to studying marlin fossils, collaborated enthusiastically with a large amount of data that hadn’t been published. With this, Carlos refined the analysis and achieved his objective.

First, he was able to work on improving the descriptions of all the other extinct species. He also detected the presence of additional species, which are being described based on other fossils he collected.

“Most fossil species were described a long time ago, and the descriptions had some problems. I hope this work will help all those interested in studying them,” he says.

While he closes a cycle with this project, Carlos is preparing for the next. Soon he will begin his doctorate studies at the University of Vienna (Austria), thanks to a grant from Panama’s Senacyt. There, Carlos will continue to study fish fossils, but much older ones, in geological time periods that go from 120 to 93 million years ago, when dinosaurs roamed the Earth.

During his explorations of the ‘Chagres Formation’, Carlos discovered the largest and best-preserved marlin fossil known, embedded in sediments more than 6 million years old. Photo by Jorge Aleman, STRI.

During that period, there were two global anoxic events in the ocean. That is, intervals of time in which the oxygen levels in the water dropped dramatically, directly affecting all marine life. Carlos seeks to evaluate the diversity and distribution of fish during these events, to understand their impact over them.

“Currently, the temperature of the seas is increasing and the oxygen dissolved in the water is decreasing. This research can help us to better understand what is happening at this moment in the ocean, and to predict how the tropical marine fauna will react to warming conditions and extreme anoxia,” says Carlos.

After his doctorate, he hopes to continue applying his knowledge of vertebrate fossils to climate projections. He would also be delighted to join an academic institution, in which he could train new scientists, as well as do research. It would be a way to pass on the kinds of opportunities he has benefitted from throughout his scientific career.

“My experience at the Smithsonian has been important to develop the kind of projects I'm doing now,” Carlos stresses. “Thanks to Dr. Carlos Jaramillo, my mentor, I was able to dedicate myself to working on what I was passionate about. He took my proposal and simply told me: do it, and tell me what you need.”

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