What led to the world’s first known mass extinction 540 million years ago? Not a meteorite or volcano but the rise of early animals, said a new study emphasizing the environmental destruction by these complex early life organism.
Since early life consisted of Ediacarans, the world’s first multicellular organisms, the study says it was the appearance of complex animals capable of altering their environments, that resulted in the Ediacaran’s disappearance.
“People have been slow to recognise that biological organisms can also drive mass extinction,” said Simon Darroch of Vanderbilt University in Tennessee, US. “But our comparative study of several communities of Ediacarans, the world’s first multicellular organisms, strongly supports the hypothesis that it was the appearance of complex animals capable of altering their environments, which we define as ‘ecosystem engineers,’ that resulted in the Ediacaran’s disappearance,” Darroch said.
While microbes or single-cell micro-organisms ruled the Earth for more than three billion years, the multi-cellular organisms like Edicarans emerged and in their heyday, they spread throughout the planet. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses.
After 60 million years, evolution saw the rise of animals, which burst into a frenzy of diversification that palaeontologists call the Cambrian explosion, a 25-million-year period when most of the modern animal families – vertebrates, molluscs, arthropods, annelids, sponges and jellyfish – came into being. These new species were ‘ecological engineers’ who changed the environment and led to the extinction of the Ediacarans, Darroch said.
Based on an extensive palaeoecological and geochemical analysis of the youngest known Ediacaran community exposed in hillside strata in southern Namibia in Farm Swartpunt site that is supposed to be 545 million years old, the researchers have finally ruled out any extraneous factors to mass extinction.
Darroch and his collaborators conclude that “this study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering and biological interactions may have ultimately caused the first mass extinction of complex life.”
Their study was published in the journal Proceedings of the Royal Society B.