Professor Proves Mass Extinction of Land and Sea Biodiversity 250 Million Years Ago Did Not Occur Simultaneously

Natural Sciences3 MIN READ

Vertebrate fossil record from earlier studies is inaccurate.

Two of Gastaldo's student researchers, Alyson Churchill '19 (left) and Oriana Battifarano '17 at work on the Bethel Farm Project in South Africa.
By Gerry Boyle
December 5, 2019

New research from a team of leading scientists led by Colby College professor and geologist Robert Gastaldo has revealed the most definitive proof to date that a near-instantaneous marine and terrestrial end-Permian mass extinction did not occur simultaneously. The important findings, recently published in the leading academic journal PALAIOS, have significant implications on the impact of a future biosphere crisis driven by climate change and a warming planet.

The groundbreaking research conclusively shows that the vertebrate fossil record reported from earlier studies – which has been used as the standard to interpret the Earth’s largest known mass extinction (i.e. the Great Dying) – is inaccurate and not sufficient enough to substantiate the long-held belief that marine species and terrestrial vertebrate, including pre-mammal synapsids, perished together.

The findings, which resulted from 15 years of research in South Africa’s Karoo Basin, show that an event took place 250 million years ago that devastated marine life, but that it didn’t affect life on land. In fact, terrestrial change happened hundreds of thousands of years earlier and very gradually. 

“While the initial goal was to corroborate conclusions of earlier studies about what is known as the End-Permian event, our data have consistently been at odds with what has been reported,” said Robert Gastaldo, the Whipple-Coddington Professor of Geology at Colby College. “Purportedly extinct creatures, including the members of the synapsids, were actually roaming around the Karoo in South Africa hundreds of thousands of years after modern scientists had written them off. Just as important, their successors were equally alive before they were supposed to have evolved.”

The research team, which included students from Colby, came to this conclusion after examining placement of fossil remains in the markedly revealing rock layers of the Karoo Basin. They also noted that fossils of pollen and spores show that vegetation changed to reflect a slow shift to plants that were adapted to drier climates. Additionally, magnetic polarity evidence in these rocks at the time of that extinction event is the opposite of the polarity recorded in the oceans at the time when now fossilized marine animals went extinct.  

According to Gastaldo, these conclusions should concern more than just geologists and other earth historians.

“The theory is that oceans suffocated and there was a mass marine die-off due to erupting volcanoes that released gases—including massive amounts of carbon dioxide and sulfur—into the atmosphere. However, if the volcanic effect didn’t cause the die-offs on land—as previous studies say—what did? Another form of global warming? And, if that’s the case, could climate change bring on another mass extinction on land? If that’s a possibility it’s imperative that we have an accurate understanding of what happened in the past so we can prepare for the future.”

Gastaldo and his colleagues are currently studying sites in China and other areas across the globe to answer these questions and further advance their research to help prepare for potentially similar cataclysmic events in the future.