Penetrative trace fossils from the late Ediacaran of Mongolia: early onset of the agronomic revolution.

摘要: The Cambrian radiation of complex animals includes a dramatic increase in the depth and intensity bioturbation seafloor sediment known as ‘agronomic revolution’. This transition was coupled with shift dominant trace fossil style from horizontal surficial traces late Precambrian to vertically penetrative fossils Cambrian. Here we show existence first latest Ediacaran: dense occurrences U-shaped Arenicolites marine carbonates Western Mongolia. Their Ediacaran age is established through stable carbon isotope chemostratigraphy their occurrence stratigraphically below appearance Treptichnus pedum . These are large diameter, penetrate down at least 4 cm into sediment, were presumably formed by activity bilaterian animals. They preserved commonly paired circular openings on bedding planes maximum diameters ranging up almost 1 cm, U- J-shaped tubes vertical sections beds. Discovery these demonstrates that agronomic revolution started earlier than previously considered.