Many people are aware that an asteroid led to the extinction of the dinosaurs millions of years ago. However, new research from the University of Birmingham has been investigating how major volcanic eruptions over 230 million years ago actually led to the rise of dinosaurs
By analyzing sediment and fossil plant records from a lake in Northern China’s Jiyuan Basin, scientists have matched volcanic activity pulses with the Late Triassic Carnian Pluvial Episode (CPE). This event increased global temperatures and humidity, ultimately resulting in rapidly increased development speeds of animal and plant life.
“Within the space of two million years the world’s animal and plant life underwent major changes including selective extinctions in the marine realm and diversification of plant and animal groups on land,” explained study co-author Jason Hilton, professor of Palaeobotany and Palaeoenvironments at the University of Birmingham’s School of Geography, Earth and Environmental Sciences. “These events coincide with an interval of intense rainfall known as the Carnian Pluvial Episode.”
“Our research shows that this period can actually be resolved into four distinct events, each one driven by discrete pulses of powerful volcanic activity associated with enormous releases of carbon dioxide into the atmosphere.”
The team discovered that large perturbation of the global carbon cycle, climatic changes to human conditions, and the lake’s deepening with a corresponding reduction in animal life and oxygen, all coincided with volcanic eruption phases.
“In addition to dinosaurs, this remarkable period in Earth history was also important for the rise of modern conifer groups and had a major impact on the evolution of terrestrial ecosystems and animal and plant life – including ferns, crocodiles, turtles, insects and the first mammals,” said Professor Hilton.
Increased rainfall also resulted in the widespread expansion of drainage basins converging into swamps or lakes as opposed to rivers and oceans, indicated by geological events within the same timeframe across other continents.
“Our results show that large volcanic eruptions can occur in multiple, discrete pulses, demonstrating their powerful ability to alter the global carbon cycle, cause climate and hydrological disruption and drive evolutionary processes,” noted study co-author Dr. Sarah Greene.
The researchers investigated terrestrial sediments from the ZJ-1 borehole in the Jiyuan Basin of North China. They used high-resolution chemostratigraphy, palynological and sedimentological data in addition to uranium-lead zircon dating in order to correlate regional terrestrial conditions with synchronous large-scale volcanic activity in North America.
Dr Emma Dunne, a paleobiologist at the University of Birmingham who was not involved in the study, commented that “at this time, the dinosaurs had just begun to diversify, and it’s likely that without this event, they would never have reached their ecological dominance we see over the next 150 million years.”
The research is published in the journal Proceedings of the National Academy of Sciences (PNAS).