Its name is Paratethys and it was the largest mega-lake that has ever existed on our planet. It contained more water than 10 times the volume of all modern lakes combined, covering more than 2.8 million square kilometers at its best; even slightly larger than the Mediterranean Sea itself (which is 2.5 million square kilometers in area). It was so colossal that it would have spread from the eastern Alps to what is now Kazakhstan in central Asia.
What happened to the megalago?
The European continent during the late Miocene was quite different from how we know it today. The immense megalake disappeared as a result of a “disaster” that wiped out most of its life forms less than 10 million years ago, according to a new study published in Scientific Reports that identifies up to four cataclysmic cycles driven by the climate that shrunk the lake and likely killed a significant number of its home species.
The lake would have contained tremendous aquatic life: from mollusks and crustaceans to small whales and dolphins that would have evolved to adapt to this “small” environment with restrictions. But few creatures survived as the lake dwindled, lost to evaporation, and increased in salinity. The lake fragmented and the central basin, which is now the Black Sea, became particularly toxic and barren.
“It must have been a post-apocalyptic prehistoric world, an aquatic version of the Mad Max moors,” says geologist Wout Krijgsman of the University of Utrecht in the Netherlands and a co-author of the work.
The researchers based their estimates on geological and fossil records within the Black Sea, where Paratethys originally existed. In addition to the Black Sea, the Caspian Sea, the Aral Sea, Lake Urmia, Lake Namak and many others, are also remnants of the Paratethy s mega-lake that was formed about 12 million years ago, after a giant sea was disconnected. from the ocean, and life evolved independently for 5 million years, isolated from the rest of the world.
The study
To reach this conclusion, the experts studied fossil records, sedimentary deposits, and the geology of the area around the Black Sea (the center of Paratethys) to identify four major drops in water level over several million years, while simultaneously making a modeling and simulation of water levels throughout the region. The most severe drop occurred between 7.65 million and 7.9 million years ago. During this episode (called the Great Khersonian Drought ), the water levels of Paratethys plummeted to 250 meters, separating the megalake into small lakes that would have been toxic to most aquatic life. According to scientists’ calculations, the megalake could have lost up to 70% of its surface and up to a third of its volume during these periods of severe drought. Crises similar to the drying up of Lake Aral, but on a larger scale.
“The partial desiccation of megalages coincide with changes in climate, the food web and the landscape in Eurasia, although the exact triggers and mechanisms have not yet been resolved,” the authors note.
Referencia: Palcu, D.V., Patina, I.S., Șandric, I. et al. Late Miocene megalake regressions in Eurasia. Sci Rep 11, 11471 (2021). https://doi.org/10.1038/s41598-021-91001-z
