Ancient reptile fossil shines new light on early marine evolution

Scientists Uncover 246 Million-Year-Old Fossil Shedding New Light on Early Marine Evolution

Around 252 million years ago, Earth experienced “The Great Dying,” an extinction event devastating 95% of life forms on land and in the oceans. In its aftermath, new species emerged, including marine reptiles transitioning from land to sea.

Among these ancient aquatic reptiles were the Sauropterygians, which thrived for approximately 180 million years during the Mesozoic era (251 to 66 million years ago). Nothosaurs, a type of Sauropterygian, existed during the Triassic period (251 to 200 million years ago), marking the dawn of the age of dinosaurs.

However, early knowledge of their evolution was limited to fossils found primarily in the Northern Hemisphere, as detailed in a study published in Current Biology.

Lead author Benjamin Kear, a paleontologist at Uppsala University’s Museum of Evolution in Sweden, highlighted that fossils of these creatures have been predominantly unearthed in Europe, southwest China, the Middle East, and sporadically in Wyoming and British Columbia.

The discovery of a nothosaur vertebra in New Zealand challenges previous findings, as the Southern Hemisphere was previously thought devoid of such fossils. The fossil, found in 1978 along Balmacaan Stream near Mount Harper, was stored in New Zealand’s National Paleontological Collection and examined by an international team of paleontologists last year.

This singular vertebra extends the sauropterygian fossil record in the Southern Hemisphere by more than 40 million years, pushing it back to 246 million years ago. Kear emphasized the significance of this find, noting that it coincides closely with the emergence of dinosaurs and suggests early globalization among marine reptiles.

The study posits that these reptiles navigated Earth’s poles, likely following a continuous coastal route around the supercontinent Pangaea. Nothosaurs, characterized by their slender bodies, long necks, limbs, and tails, were adept ocean predators, evolving paddles for more efficient swimming over time.

Looking ahead, Kear expressed plans to conduct further fossil searches globally, aiming to trace these creatures’ migration routes and deepen understanding of their adaptation to marine life.

“This discovery unveils a narrative predating the super extinction event, revealing early adaptations to oceanic environments,” Kear remarked. “As we continue our excavations, we hope to uncover more insights into their ancient journeys and evolutionary paths.”