ARCHAEOPTERYX, a toothy, feathered fossil found in Germany in the 19th century, hinted at a crucial moment in one of the greatest transitions in the history of life—the point when dinosaurs (which have teeth) took to the skies, and birds (which have feathers) were thus born. There are not many evolutionary journeys that can rival this, but that made by the descendants of some small, terrestrial mammals, which turned into the gargantuan aquatic krill-eaters called baleen whales, is one such. Analysis of a newly discovered toothy, finned fossil from America, just published in Current Biology by Jonathan Geisler of the New York Institute of Technology and his colleagues, promises to illuminate one part of this remarkable journey.
Mysticetes, as baleen whales are known technically, feed by sucking in large volumes of water and then forcing it out of their mouths through fibrous outgrowths known as baleen plates, to filter out small animals for consumption. These plates...Continue reading
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