An unusually rich fossil deposit has been discovered and described by an international research team in the Atacama Desert in northern Chile. Led by Diego Volosky from the Friedrich Schiller University Jena, the group of scientists from Chile, Germany and Argentina are investigating a variety of fossils, including plants, insects, freshwater crustaceans, molluscs, fish and sharks. ?Such complete and diverse fossil communities are rare, especially given the age of the fossils?, says Diego Volosky. The finds are dated to the Triassic, the geological period around 252 to 201 million years ago. At that time, the huge southern continent of Gondwana still existed, comprising South America, Africa, Australia and Antarctica. The research group has now published its findings in the journal ?Paleogeography, Paleoclimatology, Paleoecology?.

Unusually well-preserved fossils found

The fossil finds reveal a complex and largely preserved food web from a freshwater lake. ?This discovery offers a rare insight into a Southern Hemisphere palaeoecosystem?, says Diego Volosky. Some animal groups, such as the preserved insects and fish, even represent new finds for the region. The exceptionally well-preserved condition of the fossils is also remarkable, an indication of the calm depositional conditions in the deeper parts of the former lake.

Fine-grained sediments and the low-oxygen conditions at the bottom of the lake protected the delicate remains from rapid decay and scavengers. ?Insects were thus completely preserved, as were fish skeletons with skin impressions and the reproductive organs of land plants?, says Volosky. The fossil site contains documents of life both in the lake and on the surrounding land, which can be used to reconstruct a detailed picture of the entire ecosystem.

Dr Olga Schmitz describes her involvement in the multidisciplinary research team, which has now expanded to include more than ten institutions in the three countries involved, as an incredible opportunity. Schmitz conducts research as a micropalaeontologist at the University of Jena and the Max Planck Institute for Geoanthropology in Jena. ?With my expertise in the preparation of microfossils, I was able to help extract ostracods from the rock samples, which we want to examine in more detail in a further study.? Ostracods are bivalve crustaceans that occur in almost all aquatic habitats and are usually smaller than 1 mm.