A new normal: Study explains universal pattern in fossil record

By Santa Fe Institute

Mesa Shumacher/Santa Fe Institute

Illustration of marine fossils that have existed since the Cambrian. Represented taxa include brachiopods, trilobites, ammonites, bivalves, and decapods.

Throughout life's history on earth, biological diversity has gone through ebbs and flows—periods of rapid evolution and of dramatic extinctions. We know this, at least in part, through the fossil record of marine invertebrates left behind since the Cambrian period. Remarkably, extreme events of diversification and extinction happen more frequently than a typical, Gaussian, distribution would predict. Instead of the typical bell-shaped curve, the fossil record shows a fat-tailed distribution, with extreme, outlier, events occurring with higher-than-expected probability.

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