Smarter than yer average animal. From ScienceDaily:
The event, known as the end-Ediacaran extinction, took place 540 million years ago. The earliest life on Earth consisted of microbes — various types of single-celled organisms. These held sway for more than 3 billion years, when the first multicellular organisms evolved. The most successful of these were the Ediacarans, which spread around the globe about 600 million years ago. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses.
After 60 million years, evolution gave birth to another major innovation: metazoans, the first animals. Metazoans could move spontaneously and independently at least during some point in their life cycle and sustain themselves by eating other organisms or what other organisms produce. Animals burst onto the scene in a frenzy of diversification that paleontologists have labeled the Cambrian explosion, a 25 million-year period when most of the modern animal families — vertebrates, mollusks, arthropods, annelids, sponges and jellyfish — came into being.
“These new species were ‘ecological engineers’ who changed the environment in ways that made it more and more difficult for the Ediacarans to survive,” said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University, who directed the new study described in the paper titled “A mixed Ediacaran-metazoan assemblage from the Zaris Sub-basin, Namibia,” published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. Paper. (paywall) – Simon A.F. Darroch, Thomas H. Boag, Rachel A. Racicot, Sarah Tweedt, Sara J. Mason, Douglas H. Erwin, Marc Laflamme. A mixed Ediacaran-metazoan assemblage from the Zaris Sub-basin, Namibia. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016; 459: 198 DOI: 10.1016/j.palaeo.2016.07.003
We really don’t know very much about extinction, just as we really don’t know very much about stasis
See also: Is the Sixth Great Extinction a great myth
Stasis: Life goes on but evolution does not happen