ScienceDaily (Apr. 8, 2010) — The discovery of a new fossil turtle species in Colombia's Cerrejón coal mine by researchers from the Smithsonian Tropical Research Institute in Panama and the Florida Museum of Natural History helps to explain the origin of one of the most biodiverse groups of turtles in South America.
Deep in Colombia's Cerrejon coal mine, among house-sized trucks, Edwin Cadena discovered Cerrejonemys wayuunaiki, a new species of fossil turtle, which sheds light on the evolution of turtles in the Americas and beyond. (Credit: Edwin Cadena)
About as thick as a standard dictionary, this turtle's shell may have warded off attacks by the Titanoboa, thought to have been the world's biggest snake, and by other, crocodile-like creatures living in its neighborhood 60 million years ago.
"The fossils from Cerrejón provide a snapshot of the first modern rainforest in South America -- after the big Cretaceous extinctions and before the Andes rose, modern river basins formed and the Panama land bridge connected North and South America," explains Carlos Jarmillo, staff scientist at the Smithsonian who studies the plants from Cerrejón.
"We are still trying to understand why six of this turtle's modern relatives live in the Amazon, Orinoco and Magdalena river basins of South America and one lives in Madagascar," explains Edwin Cadena, first author of the study and a doctoral candidate at North Carolina State University. "It closes an important gap in the fossil record and supports the idea that the group originated near the tip of South America before the continent separated from India and Madagascar more than 90 million years ago."
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Authors: Edwin A. Cadena ab; Jonathan I. Bloch a;Carlos A. Jaramillo b
Affiliations:
a Florida Museum of Natural History, Dickinson Hall, University of Florida, Gainesville, Florida, U.S.A.
b Center for Tropical Paleoecology and Archeology, Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
DOI: 10.1080/02724631003621946
Published in: Journal of Vertebrate Paleontology, Volume 30, Issue 2 March 2010 , pages 367 - 382
DOI: 10.1080/02724631003621946
Published in: Journal of Vertebrate Paleontology, Volume 30, Issue 2 March 2010 , pages 367 - 382
A new pleurodiran turtle, Cerrejonemys wayuunaiki, from the middle to upper Paleocene, Cerrejn Formation of Colombia, is described on the basis of a complete skull, lower jaw, partial carapace and plastron, two cervical vertebrae, a right coracoid, and both pelvic girdles.Cerrejonemys wayuunaiki shares a suite of diagnostic characteristics with Podocnemididae, including a fully developed, medially extensive cavum pterygoidei that is almost completely covered by the prolonged posterolateral flanges of the pterygoid, a posterior elongation of the secondary roofing of the skull composed of the parietal and the quadratojugal covering two-thirds or more of the cavum tympani, a dentary covered laterally by the surangular, and no contact between the exoccipital and quadrate. Cerrejonemys wayuunaiki is unique among podocnemidids in having ridges on the ventral margin of the dentary, dentaries that form an acute angle at the fused symphysis, and a relatively thick (up to 35 mm) carapace and plastron. Results from a cladistic analysis of panpodocnemidids indicate that C. wayuunaiki is the sister taxon of the genus Podocnemis, which ranges from the Miocene to Recent, implying that stem ofPodocnemis spp. were inhabiting tropical South America early in the Paleogene.
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