The rise and fall of the world’s largest lake
https://www.sciencemag.org/news/2021/06/rise-and-fall-world-s-largest-lake
Excerpt: When continental plates smashed together about 12 million years ago, they didn’t just raise new mountains in central Europe—they created the largest lake the world has ever known. This vast body of water—the Paratethys Sea—came to host species found nowhere else, .... At its largest, the body of water—which some scientists consider to have been an inland sea—stretched from the eastern Alps into what is now Kazakhstan, covering more than 2.8 million square kilometers. That’s an area larger than today’s Mediterranean Sea, they write this week in Scientific Reports. ...climate shifts caused the lake to shrink dramatically at least four times in its 5-million-year lifetime, with water levels falling by as much as 250 meters between 7.65 million and 7.9 million years ago. ...That sent water salinity in the lake’s central basin—which closely matches the outlines of today’s Black Sea—skyrocketing, from about one-third as salty as today’s oceans to a level on par with seawater. ...Those shifts wiped out many aquatic species.... Creatures that could survive the brackish water, including some mollusks, survived to repopulate the lake when it expanded during wetter times, .... ...The Paratethys soon became home to a wide variety of mollusks, crustaceans, and marine mammals found nowhere else on Earth. Many of the whales, dolphins, and seals living there were miniature versions of those found in open seas.... ...One species, the 3-meter-long Cetotherium riabinini—1 meter shorter than today’s bottlenose dolphin—is the smallest whale ever found in the fossil record. Such dwarfism might have helped these animals adapt to a shrinking Paratethys, Gol’din says. The changes to the climate that triggered lake shrinkage also influenced the evolution of land animals, .... As water levels dropped, the newly exposed shorelines became grasslands—and hot spots for evolution.... ...Four lengthy dry periods that occurred between 6.25 million and 8.75 million years ago likely drove those creatures to migrate southwestward into Africa, Böhme and her colleagues reported last month in Communications Earth & Environment. Here, they evolved to produce the diversity of creatures for which today’s African savanna is famous...