The first animals appeared at the end of the Ediacaran period, about 580 million years ago. Examination of fossils shows that after this initial explosion, diversity declined sharply, and 40 million years later – the “Cambrian explosion” of life, characterized by a new increase in the number of species. This decline in diversity is thought to be evidence of a mass extinction about 550 million years ago. It may have been caused by an environmental disaster.

what is known

Scientific studies have shown that the first animals formed complex ecosystems before the Cambrian explosion. Suggests analysis inheritance, not mass extinction.

Dr. Mitchell scans the surface of the stone with a laser. In the foreground are Ediacaran organisms such as Fractofusus. Due to the fine features of fossils, they are only clearly visible at a certain angle of sunlight / Photograph by Charlotte G. Kenchington

• Researchers from the University of Cambridge (UK) analyzed the structure of the biocommunity of three fossil complexes spanning between 575 and 543 million years ago – the last 32 million years of this geological period.
• The analysis revealed complications in the structure of communities over time. At the end of the Ediacar period, species became more specialized and engaged in more active interspecies interactions; this is often observed during the gradual change of ecosystem types.
• The authors argue that the reason for the decline in diversity during the late Ediacaran period was that some species gained competition from others.
• Like this, The catastrophe was not a mass extinction.
• Features of ecological and evolutionary dynamics often associated with the Cambrian explosion (specialization and narrowing of niches) were established by early animal populations in the late Ediacaran period.

We found that the factors behind the eruption actually started much earlier than previously thought, during the Ediacaran period.
– says Emily Mitchell, one of the study’s authors.

Thus, the Ediacaran period was the factor that ignited the Cambrian explosion.