The Ediacaran fauna vanishes
The world's first mass extinction — possibly caused by animals
See it on the timeline →In depth
The Ediacaran organisms disappear from the fossil record over a few million years before the Cambrian boundary at 538.8 million years. The leading hypothesis is "biotic replacement": Ediacaran forms lived on and off microbial mats on the sea floor, and the new burrowing, grazing bilaterians destroyed those mats — ecosystem engineering that removed the basis for the entire fauna. Alternative explanations point to changes in ocean chemistry or oxygen crises. Whatever the cause, the outcome is that one world of body plans is replaced by another, and the new one is the one we still live in.
For children
The large soft creatures that had filled the sea floor for over thirty million years disappear almost at once. One possible explanation is uncomfortable: the new animals that could burrow, crawl and eat destroyed their habitat. The world's first mass extinction may have been caused by life, not by a catastrophe.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org