Scientists have found a missing piece in the puzzle of the world's evolutionary history. A new report explained how near-shore oceans helped ancient species diversify.

Finding An Answer To An Age-Old Mystery

About 480 million years ago, the only vertebrates that exist on Earth were fishes. By around 420 million years ago, a bigger variety of fishes appeared.

Scientists know this as a fact based on fossil records. However, the gap between that timeline, particularly, the conditions that allowed the variety of species to bloom, has remained a mystery.

A new research published by the journal Science postulates that shallow waters near the shore might have fostered the emergence of the new species. The new research also proposes that the vertebrates existing today might have come from similar marine environments some 480 million to 360 million years ago.

"In modern conceptions, we see that coral reefs are so important for fish biodiversity, so we assume there's an ancient link between fishes and reefs going back to the beginning," stated Lauren Sallan, a paleobiologist from the University of Pennsylvania and one of the authors of the study. "But decades of searching in places like the Cincinnati Arch have come up empty."

The Cincinnati Arch is the geological arch-like structure that extended from Ohio to Tennessee. A low-lying area situated between seas, the Cincinnati Arch was an influential part of the Paleozoic Era hundreds of millions of years ago.

The research also answers the mystery of why there is a gap in the fossil record. Because of the gentle waves crashing in the shoreline, the fish fossils during the time might have been smashed into smaller pieces.

Reconstructing A Missing History

To reconstruct the missing part of the fossil record, the researchers used big data and mathematical modeling to predict the habitat type from which the ancestors of each group of vertebrates emerged. They used over 2,600 early vertebrates from 480 million to 360 million years ago.

"For vertebrates, we find that they're originating in this unexpected, really restricted shallow area of the oceans," stated Sallan. "And they stay in this limited area for a long time after they emerge."

The researchers do not know why the vertebrates stayed in the shallow parts of the water, however. Whatever the environment provided, it allowed the creatures to adapt and evolve.