New research suggest that the Hangenberg extinction event 359 million years ago event that wiped out 97 percent of vertebrate species. Before the event, large creatures were the norm, but, for at least 40 million years following the die-off, the oceans were dominated by markedly smaller fish.
"Some large species hung on, but most eventually died out," Sallan said. "So the end result is an ocean in which most sharks are less than a meter and most fishes and tetrapods are less than 10 centimeters, which is extremely tiny.
"Rather than having this thriving ecosystem of large things, you may have one gigantic relict, but otherwise everything is the size of a sardine," said Sallan, an assistant professor at U Penn. Read more at: Phys Org
