A study suggests that the explosion of animal life during the Cambrian period was triggered by "cascade of events" and not by a single event.
Numerous theories were offered for several years in attempt to explain the sudden appearance of different species about 520 million years ago and one of them is the famous "Big Bang" theory.
The study led by Oxford University's Prof. Paul Smith and Durham University's Prof. David Harper presented a less unilateral theory but instead recommended a holistic way of unearthing the causes of what is now called the "Cambrian Explosion."
Theories attempting to explain this event are normally categorized into three: (1) geological, (2) geochemical, and (3) biological. Most of them were single-process theories claiming to be major triggers of the animal life explosion.
Odd but amazing animals had emerged in the Cambrian period including the Anomalocaris, a one meter long dominating predator that swims freely. Its mouth has 32 overlay of teeth which could squeeze prey to their deaths. It is a predecessor of modern-day antropods like lobsters and crabs.
Other animals from the vertebrate family also first came out in the same period. These were believed to be the ancestors of reptiles, fish, birds, and mammals.
The researchers worked on the Arctic Ocean site located in the far northern part of Greenland. This remote area of Siriuspasset is tough to reach but it promises very attractive fossils and spells a lot of relevant insights for their study.
"This is a period of time that has attracted a lot of attention because it is when animals appear very abruptly in the fossil record, and in great diversity. Out of this event came nearly all of the major groups of animals that we recognize today," Prof. Smith wrote.
The interacting occurrences were termed as the "cascade of events" which began with the sea level rising during the period. This allowed a large expanse of sea floor available for animal habitat and eventually precipitated increase of diversification of species. These then ensued further complicated, interlinked processes that were previously presented individually as single causes for the series of developments.
"It would be naive to think that any one cause ignited this phenomenal explosion of animal life. Rather, a chain reaction involving a number of biological and geological drivers kicked into gear, escalating the planet's diversity during a relatively short interval of deep time. The Cambrian Explosion set the scene for much of the subsequent marine life that built on cascading and nested feedback loops, linking the organisms and their environment, that first developed some 520 million years ago," Prof. Harper added.
The study was published in the Sept. 19 issue of the online journal Science.
