Between 6.4 and 5.8 million years ago, most of the land bridge connecting North and South America had emerged and the channels connecting the Pacific and Atlantic oceans were shallow. Recent fossils discovered in the northern Panama Canal area suggest that marine species interacted in these shallow waters during the final stages of isthmus formation.
In 2017 and 2019, Aldo Benites-Palomino was studying fossils collected in Caribbean Panama, when he found some unexpected specimens. He was a biology student in Perú, where his training was very classical. As an intern and later a fellow at the Smithsonian Tropical Research Institute (STRI), his thinking changed. His teacher, STRI staff scientist and paleobiologist Carlos Jaramillo, encouraged his students to change their focus when looking at fossils: instead of thinking about specimens or methods, to think about to questions that fossils can help answer.
“I wanted to go to STRI because it’s the most important center for tropical biology in the world,” Benites-Palomino said. “There I learned a lot about the way biology and ecology work in the modern world.”
The fossil remains belong to small cetaceans, a group of aquatic mammals that include whales and dolphins, and the specimens are new for the region. Most of them were collected by Carlos de Gracia from STRI and Jorge Velez Juarbe from the Los Angeles Museum of Natural History, both co-authors of a new paper published in Biology Letters. In the article, Benites-Palomino and his colleagues go beyond describing the specimens, they also capture the story they reveal about the isthmus’ deep past.
The fossils belong to the Late Miocene, about 6.4 to 5.8 million years ago, when the final stages of isthmus formation began. This phenomenon affects ocean waters and ocean currents around the world and causes speciation events, where species separated by land bridges develop their own unique characteristics in any ocean.
However, these cetaceans found in Caribbean Panama share similarities with other Late Miocene species from the North and South Pacific Oceans, particularly the Pisco Formation of Peru, suggesting that some organisms were still able to disperse. through the shallow sea during the deep water exchange. between two oceans no longer happened.
The lack of fossil marine mammals from the western Caribbean currently hinders the understanding of the deep past of the region, so these new findings help to strengthen the current knowledge about the connection between the Pacific and Caribbean marine fauna of the time. in the final stages of isthmus formation.
“Panama’s marine vertebrate fossil record is virtually unexplored,” said Carlos Jaramillo, STRI staff scientist and co-author of the study. “There are many more specimens to be studied and many more rocks waiting to be found.”
Aldo Benites-Palomino et al, Connecting two oceans: small-toothed cetaceans (Odontoceti) from the Late Miocene Chagres Formation, eastern Caribbean (Colon, Panama), Biology Letters (2023). DOI: 10.1098/rsbl.2023.0124
Provided by the Smithsonian Tropical Research Institute
Citation: Marine fossils unearthed story about Panama’s deep past (2023, July 13) retrieved on 13 July 2023 from https://phys.org/news/2023-07-marine-fossils-unearth- story-panama.html
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