ReviewOnline nowAugust 04, 2026
The Cambrian fecal revolution: Fueling the Cambrian Radiation
Julien Kimmig1,2,3 Send email to julien.kimmig@smnk.de ∙ Russell D.C. Bicknell4,5
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The ‘Cambrian Radiation’ comprises the rapid diversification of marine organisms and ecological niches during the Ediacaran to Cambrian Periods. It is also the time during which animals with guts first appear. The appearance of guts, in turn, leads to fecal matter, fossils of which are preserved as coprolites.
Fecal matter is rarely preserved in the Cambrian. However, in a few assemblages, the diversity and development of fecal matter are observed. There was little fecal matter available at the onset of the Cambrian, while larger and more diverse fecal matter became available by the middle Cambrian.
We assess the effect that increased availability of fecal matter had on deeper water environments and how this made such environments habitable for Cambrian organisms.
Combining these observations with data on digestive tracts and biogeochemistry of nutrient cycling in the Cambrian demonstrates that fecal matter played a significant role in driving the Cambrian Radiation.
Abstract
Coprolites—fossil material extruded from an animal’s digestive system—represent a rare insight into trophic interactions in deep time. However, while the first animals appeared about 600 million years ago, the first coprolites are only observed in the earliest Cambrian. Conversely, in modern oceans, fecal pellets are an important part of the particulate organic carbon in the water column and the global flux of organic carbon to deep water. In this review, we analyze the impact of the advent of fecal matter on the Cambrian Radiation by examining coprolites, analyzing animal biology, and contextualizing this through the role of fecal pellets in the oceanic nutrient cycle. We illustrate the central position of coprolites in driving the Cambrian Radiation.
https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(26)00156-4