rapid diversification of multicellular animal life ~541 million years ago
most major animal phyla appeared within a ~25 million year window
origin of eyes, shells, exoskeletons, predation, bilateral symmetry
preceded by the Ediacaran biota: soft-bodied, sessile organisms
triggers: rising oxygen levels, calcium availability, ecological arms races
first appearance of arthropods, mollusks, chordates, echinoderms
the Burgess Shale and Chengjiang fossil beds preserve this radiation
deepest example of an epoch boundary driven by innovation cascades
analogous to the Information Age explosion of digital complexity