60秒科学:鲸鱼祖先统治海洋多久？（在线收听）

《科学杂志》上的一项研究表明，硬骨滤食性鱼类用了10亿年的进化时间，占据了须鲸类现在的生态龛。另一项研究表明，鲸类的多样化取决于其食用的微生物类型。

Sometimes scientific discoveries are hidden in museum specimen drawers and old journal articles. In two studies in the journal Science, researchers who went through the stuff in institutional attics offer new insights into the development and diversity of filter-feeding whales—and the fish that first occupied that ecological niche.

It had been thought that mammoth, filter-feeding fish—which swam through the water with a gaping, open mouth, collecting tiny marine creatures—only lived fleetingly before whales took their place in the food chain.

But a research team [led by Matt Friedman, University of Oxford] decided to take a closer look at museum fossils of bony, pre-historic fish that had either been misclassified or ignored. They also reexamined previous studies.The investigators now say that these fish filter-feeders lived from about 170 to 65 million years ago, a healthy stretch in which to pioneer and perfect the niche.

In a related study, scientists [Felix Marx, University of Otago, New Zealand and Mark Uhen, George Mason University] show that when filter-feeding whales took over from bony fish, their diversity was linked to the diversity of their dinner—the tiny creatures at the very bottom of the food chain –tiny algae known as diatoms