Previously, the oldest-known fossils of a number of modern groups of deep-sea organisms were found in shallow-water deposits. This suggested that these modern deep-sea creatures evolved from immigrants from shallow waters. The newfound fossils Thuy and his colleagues analyzed, which predate earlier findings by more than 25 million years, instead suggest that these ancient shallow-water animals may have actually evolved from deep-sea ancestors.
Moreover, when the researchers compared deep-sea fossils with shallow-water fossils of the same age, they found significantly more biodiversity in the deep sea than in shallow seas for at least some of the groups of animals. This suggests that the deep sea can be more successful at sheltering animals from extinction than shallow coastal seas.
"However, we should not assume the deep sea is robust against any man-made disturbance," Thuy said. That would be a dangerous misinterpretation of our results, he said.
The scientists detailed their findings online May 21 in the journal Proceedings of the Royal Society B.
Original article on Live Science.
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