Tuesday, February 25, 2014

Most of the rorqual skeletons were complete, well-preserved, and belly-up. There was even a group of two adults and a youngster, log-jammed together and beautifully preserved. All of this suggests that they died at sea and were washed onto tidal flats, where they were quickly buried. And since the fossils were found in four separate layers, these mass strandings happened repeatedly in this same place. 
What killed such a diverse group of animals, time and again? “Every explanation must work across all the taxa, and must also satisfy what you see about the bones and their arrangement,” says Pyenson. “And it has to explain the pattern four times.” 
Pyenson says there is only one cause that fits all the available evidence: