Dinosaurs' ascent driven by volcanoes powering climate change

The Carnian Pluvial Episode of 230 million years ago saw intense volcanic activity that led to ecological changes that allowed dinosaurs to emerge as the dominant species. Credit: Pixabay
A new study has revealed that the rise of dinosaurs was correlated with major volcanic eruptions more than 230 million years ago.

The Late Triassic Carnian Pluvial Episode, (CPE), saw an increase of global temperature and humidity. This had a significant impact on the development and life of animals and plants. It also coincided with the establishment modern conifers.

Researchers analysed sediment and fossil plant records taken from Jiyuan Basin in northern China. They found that the volcanic activity was associated with significant changes in the environment, including the CPE's mega monsoon climate. This is some 234 to 232 millions years ago.

Today, a team of international researchers, including experts from the University of Birmingham published their findings in Proceedings of the National Academy of Sciences. They found four distinct episodes of volcanic activity over this period. The most probable source was major volcanic eruptions in the Wrangellia Large Igneous province, whose remnants are still preserved in western North America.

Jason Hilton, Professor of Palaeobotany and Palaeoenvironments, University of Birmingham's School of Geography Earth and Environmental Sciences commented that the co-author of the study said: "In the span of two million years, the world's animal and plants underwent major changes, including selective extinctions within the marine realm and diversification of animal and plant groups on the land. These events occur in conjunction with an extraordinary period of intense rain known as the Carnian Pluvial Episode.

"Our research shows that the period can be broken down into four events, as shown by a detailed record taken from a lake north of China. Each event is driven by distinct pulses of volcanic activity and huge carbon dioxide releases into the atmosphere. These events triggered an increase of global temperature and humidity.

Researchers discovered that each stage of volcanic eruption was associated with major perturbations of the global Carbon cycle and major climate changes to more humid conditions. The lake's depth also coincided with a decrease in oxygen and animal lives.

Geological events that occurred in the same time frame in Central Europe and North America (East Greenland, Morocco), North America and Argentina, among others, indicate that more rainfall led to widespread expansion of drainage basins that converged into lakes or swamps rather than rivers or oceans.

"Our results demonstrate that large volcanic eruptions can occur simultaneously in discrete pulses, demonstrating their power to alter the global carbon cycle and cause climate and hydrological disruption and driving evolutionary processes," said Dr. Sarah Greene (co-author) and Senior Lecturer in the School of Geography and Earth Sciences at the University of Birmingham.

Dr. Emma Dunne (a Palaeobiologist at the University of Birmingham) commented on the study but was not involved.

"This long period of volcanic activity would have had significant consequences for animals on the land. The dinosaurs were just beginning to diversify at this point, and without this event they wouldn't have achieved the ecological dominance that we see in the next 150million years.

Professor Hilton added, "In addition dinosaurs, the remarkable period in Earth's history was also important to the rise of modern conifer group and animal and plant life including ferns. Crocodiles. turtles. insects and the first mammal."

The team studied terrestrial sediments in the ZJ-1 borehole, Jiyuan Basin, North China. The team used high-resolution chemostratigraphy and uranium-lead Zircon dating to determine if the region was prone to large-scale volcanic activity.

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More information: Lacustrine ecosystem changes triggered by volcanic activity during the Carnian Pluvial Episode, (Late Triassic), Proceedings of the National Academy of Sciences (2021). Information from the Journal: Proceedings of National Academy of Sciences Volcanically-driven lacustrine ecosystem shifts during the Carnian Pluvial Episode, (Late Triassic), (2021). doi.org/10.1073/pnas.2109895118