Aquatic life picked up after global mass extinction, says research

Washington: Turns out, reptiles were pretty quick to recover and invade the seas after a global extinction wiped out most life on Earth.

A new study led by University of California, Davis, suggests that land reptiles colonized the ocean in just 3.35 million years at the beginning of the Triassic, a speedy recovery in geologic time.

“Our results fit with the emerging view that the recovery was faster than previously thought,” said study co-author Ryosuke Motani, professor of paleobiology at UC Davis’ Department of Earth and Planetary Sciences.

The research was led by Wanlu Fu of the Laboratory of Orogenic Belt and Crustal Evolution at Peking University.

The oldest marine reptile fossils appeared 248.81 million years ago, the most precise date yet, according to the study. These pioneering marine reptiles, including the dolphin-like ichthyosaurs and sauropterygians, went on to rule the Mesozoic seas during the era of the dinosaurs.

At the same time, there were major changes in ocean chemistry and carbon cycling, the team found. Vertical mixing of oceanic water had stopped during or soon after the mass extinction, causing widespread depletion of oxygen in the oceans.

Carbon isotopes in the Majiashan rock layers suggest the oldest marine reptiles appeared just after a return to healthy ocean circulation, which could have prompted the ecosystem recovery.

The rocks recorded more vigorous mixing of ocean waters, which would have brought nutrient-rich waters to the surface to fuel tiny organisms at the bottom of the ocean’s food chain.

This research has been published in Scientific Reports. (ANI)