(SF- MeI 5933) Photograph of the holotype of Bechleja brevirostris n. sp. (A) The plate, and (B) the counter plate. Journal of Scientific Reports (2022). DOI: 10.1038/s41598-022–23125-9
In the journal Scientific Reports, an international team of scientists led by the Museum für Naturkunde Berlin has described Germany's first fossil freshwater shrimp species. The majority of shrimps prefer marine habitats, but this fossilized Eocene shrimp from Grube Messel, a former freshwater lake, dates back 48 million years. Due to the preservation of even rare organ structures, the shrimp is an integral part of the reconstruction of this unique ecosystem.
"The new species Bechleja brevirostris is the first and only fossil record of freshwater shrimps from the Eocene in Europe, and the second worldwide after Bechleja rostrata from the Green River Formation in Wyoming, U.S., 8,000 kilometers away," says the Museum für Naturkunde Berlin's Alexander von Humboldt Postdoc, Valentin de Mazancourt.
By feeding on the ground, shrimp help maintain the ecosystem's balance. One would expect to find them in marine environments, coral reefs, and the deep sea, but not in a freshwater lake like the one that formed in Messel approximately 48 million years ago. However, there are also freshwater organisms. For decades, scientists at the Museum für Naturkunde Berlin have studied living freshwater shrimp in Sulawesi. In 2018, Inforadio RBB listeners gave the new species the name Caridina clandestina.
In the case of the new fossil species of freshwater shrimp Bechleja brevirostris, internal organ structures can even be deduced, which is quite uncommon for such organisms. Thus, the study of a small shrimp yields new information about the paleoecosystem of an ancient crater lake.
Due to the exceptional state of preservation and abundance of fossils, the Messel Pit likely provides the most comprehensive view of a 48 million-year-old terrestrial ecosystem. The finds are housed in the Messel collections of the Senckenberg Research Institute and the Natural History Museum in Frankfurt, as well as the Hessian State Museum in Darmstadt.
From Lower Cretaceous freshwater deposits in Brazil and Spain, as well as Tertiary deposits in France and Brazil, fossil shrimps have been described. These fossil discoveries serve as calibration points for genetically-based molecular clock analyses that date evolutionary events.
Valentin de Mazancourt et al., Exceptional preservation of internal organs in a new fossil species of freshwater shrimp (Caridea: Palaemonoidea) from the Eocene of Messel (Germany), Scientific Reports (2022). DOI: 10.1038/s41598-022–23125-9