An article published in the journal “Journal of South American Earth Sciences” describes a research that connects the discovery of fossils, mostly of turtles and tortoises as well as other organisms, in the Andes of southern Bolivia to the geological changes of the area. According to the researchers, 13 million years ago these mountains were high less than a kilometer above sea level.
This research concerns a plateau in the Andes called Altiplano in Spanish, the largest mountain plateau after the one in Tibet with an average height above 3,700 meters (about 12,300 feet). It ranges across several countries in South America and according to a recent study based on isotope measurements, 13 million years ago, in the geological period called Miocene, its height was between 2 and 3.2 km. This assessment is now contradicted by new research based on the fossils found in the Bolivian Altiplano.
Darin Croft, an anatomy professor at Case Western Reserve University School of Medicine, found the remains of a tortoise. In the same area other fragments of fossil turtles and tortoises were later found. Croft sent photographs and three-dimensional computer-generated images of these remains to Edwin Cadena, an expert on turtles who now works at Yachay Tech University in Ecuador.
Cadena identified the turtle as a species of the genus Chelonoidis, still present in South America and the Galapagos Islands (photo ©David Adam Kess). He also identified an extinct freshwater turtle of the genus Acanthochelys, which includes currently existing species in tropical South America. Those are reptiles, therefore cold-blooded animals that probably have requirements similar to those of their present cousins, who live at altitudes not exceeding 500 meters.
In Bolivia fossil leaves dating back to Miocene were also found. Their analysis indicates that they belong to species of plants that were living at temperatures higher than the current ones of the area but also lower altitudes and more precipitation. Basically, they confirm the hypothesis suggested by the presence of turtles and tortoises that 13 million years ago the Altiplano was much lower than today.
This study is only partially paleontological because in this case there’s also an investigation that aims to provide new clues about the geological history of the Andes and to get an idea of what climate there was in the area. Darin Croft stressed the importance of understanding the past to model the future. This research is just one piece of the big puzzle of the Andes history so it will take more studies in various fields to reveal it completely.
