The traditional view is that species have increased in diversity continuously over the past 200 million years, particularly in the last 100 million, leading to more diversity now than ever before. But some recent studies suggest biodiversity has tended to stay largely the same, with only occasional surges.
‘Our findings strongly contradict past studies that suggested unbounded diversity increases at local and regional scales over the last 100 million years,’ said a fresh study on terrestrial species. It found no evidence of a rise in diversity in the past 66 million years, following a brief two- to three-fold increase over a couple of million years after the mass extinction of the dinosaurs at the end of the Cretaceous Period and as mammals began to thrive.
The story was similar for a study on marine species, with the researchers finding little change in ocean biodiversity over the past 200 million years.
While researchers emphasize that past evolutionary trends are not directly translatable to today because of the vastly different timescales, they say studies could provide some clues about the ability of species to adapt and the combinations of characteristics such as feeding patterns or size that put species at risk. This research could also provide implications for how human-driven climate change might affect future evolution.