Skeleton of the early dinosaur Coelophysis bauri from the Late Triassic. The protracted restructuring of Early Jurassic terrestrial ecosystems coincided with the diversification of dinosaurs.
Image: Natural History Museum of Los Angeles County.
In that multi-billion year history of planet Earth, long before creationism's little god allegedly created a small, flat planet with a dome over it, and put living things on it, the real Earth had already had several mass extinctions when the ecosystem changed so radically and quickly that most species couldn't evolve fast enough to survive.
This give the lie to creationist claims that Earth is finely-tuned for life because, quite frankly, very few of the species that have evolved on it last more than a few million years before being killed off by one catastrophe or another that any omniscient deity worthy of the description could and should have foreseen and planned for.
The fourth of those mass extinctions occurred at the end of the Triassic period when a dramatic rise in greenhouse gasses due to volcanic activity led to rapid global warming and a significant shift in the planet’s biosphere, ending the Triassic period and launching the Jurassic.
The parallel with today when a rise in greenhouse gasses has been caused by industrial pollution and burning fossil fuels is striking.
Now a new insight into this mass extinction has been revealed by researchers from the University of Southern California's Dornsife College of Letters, Arts and Sciences, using a novel "ecospace framework" method that categorizes animals beyond just their species. It accounts for ecological roles and behaviors — from flying or swimming predators to grazing herbivores and from ocean seafloor invertebrates to soil-dwelling animals on land.
As the press release from UCSDornsife explains:
“We wanted to understand not just who survived and who didn’t, but how the roles that different species played in the ecosystem changed,” said David Bottjer, professor of Earth sciences, biological sciences and environmental studies at USC Dornsife and a study senior author. “This approach helps us see the broader, interconnected ecological picture.”More technical detail is provided in the team's paper in Proceeding of the Royal Society B:
The study — a collaboration between students and faculty at USC Dornsife and the Natural History Museum of Los Angeles County — published today in Proceedings of Royal Society B.
Sea life suffered, but not as much as land animals
The research revealed a stark difference in the impact on marine and terrestrial ecosystems. While both realms suffered greatly, the findings suggest that land-based ecosystems were hit harder and experienced more prolonged instability.
In the oceans, nearly 71% of categories of species, called genera, vanished. Surprisingly, despite this massive loss, the overall structure of marine ecosystems showed resilience. Predators like sharks, molluscs known as ammonites and filter feeders like sponges and brachiopods, though severely affected, eventually bounced back.
On land, the scenario proved much bleaker. A staggering 96% of terrestrial genera went extinct, dramatically reshaping the landscape of life on Earth. Large herbivores like early dinosaurs and various small predators suffered greatly, with significant changes in their populations and roles within the ecosystem.
“This contrast between land and sea tells us about the different ways ecosystems respond to catastrophic events,” said co-lead author Alison Cribb, who earned her PhD in geological sciences at USC Dornsife this year and is now at University of Southampton in the U.K. “It also raises important questions about the interplay of biodiversity and ecological resilience.”
Climate change clues from ancient catastrophe
The study’s findings spark more than just historical interest — they carry significant implications for our current environmental challenges. “Understanding past mass extinctions helps us to predict and possibly soften the impacts of current and future environmental crises,” said co-lead author Kiersten Formoso, who is finishing her doctoral studies in vertebrate paleobiology at USC Dornsife and will soon move to a position at Rutgers University.
Graphic representation of the study concept and findings.
Illustration: Hank Woolley.
The parallels between the rapid global warming of the end-Triassic and today’s climate change are particularly striking. “We’re seeing similar patterns now — rapid climate change, loss of biodiversity. Learning how ecosystems responded in the past can inform our conservation efforts today,” Bottjer said.
The research also provides a rare window into the world as it existed over 200 million years ago, he added. “It’s like a time machine, giving us a glimpse of life during a period of profound change.”
The study’s ecospace framework, with its focus on functional roles, offers a fresh perspective on ancient life, according to Frank Corsetti, professor of Earth sciences and chair of USC Dornsife’s Department of Earth Sciences. “It’s not just about identifying fossils,” he said. “It’s about piecing together the puzzle of ancient ecosystems and how they functioned.”
Future ventures will delve into the past’s lessons
As they plan further research, the scientists aim to explore how different species and ecosystems recovered after the extinction, and how these ancient events can parallel current biodiversity loss due to climate change.
Future studies are also planned to examine changes in ecospace dynamics across other periods of profound environmental change in deep time.
“We’ve just scratched the surface,” said Cribb. “There’s so much more to learn about how life on Earth responds to extreme changes, and this new ecospace framework offers great potential for helping us do that.”
AbstractThis work shows how the world's marine and terrestrial ecosystems, although appearing to be unconnected, inevitably affect one another so, when something catastrophic like a sudden increase in seismic activity with increased volcanic output of greenhouse gasses, followed by rapid temperature change, can cause a progressive collapse of ecosystems, resulting in a mass extinction. The few surviving species then occupy vacated niches and build new ecosystems with a rapid burst of evolutionary diversification, just as we see in the fossil record.
Mass extinctions have fundamentally altered the structure of the biosphere throughout Earth's history. The ecological severity of mass extinctions is well studied in marine ecosystems by categorizing marine taxa into functional groups based on ‘ecospace’ approaches, but the ecological response of terrestrial ecosystems to mass extinctions is less well understood due to the lack of a comparable methodology. Here, we present a new terrestrial ecospace framework that categorizes fauna into functional groups as defined by tiering, motility and feeding traits. We applied the new terrestrial and traditional marine ecospace analyses to data from the Paleobiology Database across the end-Triassic mass extinction—a time of catastrophic global warming—to compare changes between the marine and terrestrial biospheres. We found that terrestrial functional groups experienced higher extinction severity, that taxonomic and functional richness are more tightly coupled in the terrestrial, and that the terrestrial realm continued to experience high ecological dissimilarity in the wake of the extinction. Although signals of extinction severity and ecological turnover are sensitive to the quality of the terrestrial fossil record, our findings suggest greater ecological pressure from the end-Triassic mass extinction on terrestrial ecosystems than marine ecosystems, contributing to more prolonged terrestrial ecological flux.
Cribb Alison T., Formoso Kiersten K., Woolley C. Henrik, Beech James, Brophy Shannon, Byrne Paul, Cassady Victoria C., Godbold Amanda L., Larina Ekaterina, Maxeiner Philip-peter, Wu Yun-Hsin, Corsetti Frank A. and Bottjer David J. 2023
Contrasting terrestrial and marine ecospace dynamics after the end-Triassic mass extinction event
Proc. R. Soc. B.2902023223220232232 http://doi.org/10.1098/rspb.2023.2232
© 2024 The Royal Society.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
Evolution, playing to a few simple natural rules, can build a rich and dynamic picture of interdependent ecosystems, all driven by environmental change.
It also shows how Earth is not fine-tuned for life, but life is fine-tuned for an Earth that can sometimes become a very hostile environment in which species either evolve or die out. No intelligence is needed and no omniscient, controlling intelligence would continually create new species just to exterminate them with a catastrophic event that removes their support systems.
How did you come to be here, now? This books takes you from the Big Bang to the evolution of modern humans and the history of human cultures, showing that science is an adventure of discovery and a source of limitless wonder, giving us richer and more rewarding appreciation of the phenomenal privilege of merely being alive and able to begin to understand it all.
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