“What makes this exciting is not so much the actual old age of the fossils ... to those of vertebrates suggests that yunnanozoans belong among vertebrates rather than chordates, Jandzik explains, and ...

“It so not so much a Big Bang, going to a fully fledged fish,” Mussini told The New York Times. “The vertebrate body plan probably had a much more protracted assembly than we thought.

Among them were the chordates, to which vertebrates (animals with backbones) such as humans belong. What sparked this biological bonanza isn't clear. It may be that oxygen in the atmosphere ...