A new study led by researchers at the University of Oxford has determined that the shape and orientation of coastlines significantly influenced extinction patterns for animals living in shallow oceans over the last 540 million years. The research indicates that animals inhabiting convoluted or east-west oriented coastlines, similar to the modern Mediterranean or Gulf of Mexico, were more prone to extinction than those residing on north-south oriented coastlines.
Research Methodology
Published in Science, the findings resulted from an analysis of over 300,000 fossils from more than 12,000 genera of marine invertebrates. Researchers combined this fossil data with reconstructions of continental arrangements throughout geological history to develop a statistical model. This model tested the hypothesis that coastline geometry affected a taxon's likelihood of extinction.
Key Findings
The model revealed that invertebrates in environments where migration to different latitudes was difficult or impossible, such as east-west coastlines, islands, or inland seaways, were consistently more vulnerable to extinction. Conversely, groups capable of moving more easily in a north-south direction experienced a lower risk.
- Migration Advantage: North-south oriented coastlines facilitated species migration during periods of climate change, allowing them to remain within their ideal temperature ranges and reducing extinction risk.
- Geographic Traps: Species confined to a specific latitude, for instance on an island or an east-west coastline, could not escape unsuitable temperatures and consequently faced higher extinction rates.
- Exacerbated During Extremes: The study also showed that this effect was heightened during mass extinctions and hyperthermal (extremely warm) periods, with coastline geometry becoming even more critical for survival during these times.
Dr. Cooper Malanoski, the lead author from the Department of Earth Sciences, stated that palaeogeographic context is vital as it allows taxa to track preferred conditions during extreme climate change. He suggested that continental configurations might explain why some mass extinctions were more severe than others.
Modern Implications
These findings suggest that present-day species in isolated habitats that cannot easily migrate latitudinally may be particularly vulnerable to anthropogenic climate change. This information could be valuable for determining conservation priorities and identifying vulnerable marine populations in the future, especially those crucial for ecosystem services.
Professor Erin Saupe, a study co-author, affirmed that the research confirms a long-suspected theory among palaeontologists and biologists: a species' ability to migrate to different latitudes is essential for survival. The study was conducted in collaboration with the University of California, Berkeley; Stanford University; University of Leeds; and the Smithsonian Tropical Research Institute.