Plankton species diversity
Photo Credit: Christian Sardet/CNRS/Tara expeditions
(CC BY 4.0)
Scientific Frontline: Extended "At a Glance" Summary: End-Cretaceous Marine Survival Mechanisms
The Core Concept: Following the asteroid impact 66 million years ago, select marine organisms survived the mass extinction due to specific biological advantages. A recent trait-based numerical model reveals that small body size and high tolerance to darkness were the primary attributes enabling the survival of basal food chain species such as plankton.
Key Distinction/Mechanism: Unlike larger, light-dependent species adapted to warm waters, smaller planktonic organisms required significantly less energy to sustain themselves. Their inherent adaptability to lower light levels and turbulent waters allowed them to endure the catastrophic, darkness-inducing environmental shifts following the Chicxulub impact.
Major Frameworks/Components:
- Numerical trait-based modeling: Mapped global ecosystem traits to analyze the physical and chemical requirements of millions of organisms with unprecedented accuracy.
- Energy and predation trade-offs: Evaluated the balance between predation risk, food availability, and specific physical attributes such as temperature tolerance, light level dependency, and body size.
- Century-timescale causality: Addressed previous limitations regarding the lack of high-resolution fossil and environmental proxy data at the K-Pg boundary.
Branch of Science: Evolutionary Biology, Paleontology, Marine Biology, and Oceanography
Future Application: The trait-based models developed in this research provide a computational framework to forecast how current and future ecosystems will respond to anthropogenic environmental changes, particularly rising temperatures and alterations in marine light availability.
Why It Matters: Resolving the evolutionary mystery of selective ancient extinctions yields empirical, data-driven insights into systemic resilience. Understanding how foundational marine species survive extreme environmental shifts is critical for predicting the viability of the modern oceanic food web amid ongoing global warming.
A University of East Anglia researcher has helped uncover why some marine life survived the mass extinction event that wiped out the dinosaurs.
Scientists have shown that tiny marine organisms in polar oceans persisted because they needed less energy and were more tolerant of darkness.
Published in the journal Nature, the study resolves a longstanding evolutionary mystery by identifying the factors that determined which marine species would survive 66 million years ago. Their small size and ability to cope with darkness emerged as the key advantages.
Study lead author Dr. Rui Ying, from UEA’s School of Environmental Sciences, said, “It’s an exciting breakthrough. For so many years, scientists have been unable to test what actually decided whether a species prevailed or perished because the extinction event involved multiple environmental changes, such as ocean acidification and darkness. It is difficult to understand the causality because of the lack of fossil and environmental proxy data, especially at the century timescale. Using a numerical model, I looked at the base of the food chain—plankton—which helped us identify the most likely cause and the best survival strategies for plankton.”
What Happened 66 Million Years Ago?
The Cretaceous–Paleogene (K–Pg) boundary is an ancient and much-studied geological signature marking the mass extinction that wiped out non-avian dinosaurs, separating the Mesozoic Era (the age of reptiles) from the Cenozoic Era (the age of mammals).
It is thought that the impact of the Chicxulub asteroid caused the extinction of approximately 75 percent of species in the fossil record by triggering catastrophic environmental changes.
Despite decades of research, the mechanisms linking environmental changes to the selective extinction patterns observed in the fossil record have until now remained unresolved. By creating and deploying a unique model that maps ecosystem traits globally, the scientists have established which attributes resulted in the marine plankton community’s survival.
Dr. Ying, who conducted the research while at the University of Bristol, said, “The model is based on traits and the trade-off of how often they are eaten by predators and what they can eat against specific attributes, such as temperature, light level, and body size.”
Why Size Matters
Study co-author Dr. Fanny Monteiro, an associate professor in ocean sciences at the University of Bristol, said, “The body size and abundance of small plankton mean the organisms rely on less energy, increasing their likelihood of survival. An ability to deal with lower light, darkness, and turbulent waters in higher latitudes also made them more adaptable to polar regions. In contrast, species adapted to higher light and warmer waters were more vulnerable to this type of mass extinction.”
Modeling Millions of Organisms
The model allowed the traits of millions of organisms to be analyzed and quantified with unprecedented accuracy, providing important insights into the physical and chemical changes linked to diversity.
Besides shining a light on the distant past of marine life, the research can also help inform forecasts of how ecosystems might respond in the future.
Study co-author Prof. Daniela Schmidt at the University of Bristol said, “This study not only demonstrates how trait-based models can help us better understand biodiversity crises in ancient history, but it also has the potential to indicate how less light and hotter environments, as a result of global warming, might impact current and future ecosystems.”
Funding: The research was funded by a China Scholarship Council (CSC)–Bristol Ph.D. Scholarship and NERC grants.
Published in journal: Nature
Title: Darkness and body size shaped end-Cretaceous marine extinction patterns
Authors: Rui Ying, Fanny M. Monteiro, James D. Witts, and Daniela N. Schmidt
Source/Credit: University of East Anglia
Edited by: Scientific Frontline
Reference Number: ebio060826_01