A new study led by scientists at the Field Museum of Natural History in Chicago shows that the last great extinction (roughly 251 million years ago) was followed by an explosion of complex marine life that has continued to persevere to present day. According to the study, when compared to the slow gradual process of evolution, this jump to complicated ecosystems was more like a ÃÂflip of the switchÃÂ.
The researchers noticed a sudden shift towards more complex organisms when they examined marine fossil records using the Peleobiology Database (pbdb.org), a new international archive composed of at least 1176 sites worldwide.
Their research showed that before the last mass-extinction, marine life was divided equally into two types of communities, simple ones (community in which most species did not interact with each other) and complex ones (many interrelationships i.e. predator/prey).
After the mass extinction, according to Peter J. Wagner, the lead author of the study, complex communities have flourished and outnumbered the simple ones 3:1.
This shift made the oceans go from being an environment in which most species where stuck in one spot (or sessile) and fed on whatever came with the current to an environment in which the norm was that most animals hunted and searched for food (motile organisms).
Scientists are still unsure as to why this extinction had this lasting effect on the nature of communities when the other mass extinctions did not. What Dr. Wagner is sure of is that the shift towards more motile animals was a lasting trait and is seen in the more complex biological webs. He also states that ÃÂthe increased diversity of mobile species would have contributed to more complex ecological communitiesÃÂ. Sessile organisms live next to each other and thatÃÂs it. ÃÂWith mobility and higher metabolism, you bump into...