1986/04/01 by Mark A. S. McMenamin · 5 citations
Earth and Planetary Sciences · #Paleontology and Stratigraphy of Fossils #Marine Biology and Ecology Research #Marine and coastal plant biology
paper · doi:10.2307/3514512
openalex publication_date 1986/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
The faunal change across the Proterozoic-Cambrian transition can be interpreted as a shift from marine communities composed largely of soft-bodied, possibly photoautotrophic animals to communities dominated by heterotrophic Metazoa. Convincing evidence for macrophagous predation (damaged prey, actual fossils of predators, and antipredatory prey morphologies) first appears in the fossil record during the Lower Cambrian. The enigmatic Cambrian fossil, Xenusion, may be a relict member of the Ediacaran biota that developed spines to deter predators. Defensive prey morphologies such as punctae in mickwitziid brachiopods and spines on wiwaxiids appear at or just before the base of the Cambrian, and strongly suggest that predators played an important role in these earliest shelly communities. The fossil record is biased against preservation of these early predators, however, because most were soft bodied or lightly skeletonized. Abundant late Proterozoic-Early Cambrian phosphorites suggest increased photic-zone nutrient supplies during the Proterozoic-Cambrian transition, possibly as a result of paleoceanographic conditions favoring equatorial upwelling or increased nutrient runoff from the continents. By favoring heterotrophy over photoautotrophy in marine animals, increased shallow-marine nutrient supplies may be the proximal cause for the Cambrian radiation of predators and the loss of the unique Ediacaran biota.