Research

Mass Extinctions

Research activities in the Mass Extinctions area.

mass extinctions
This figure shows the genus extinction intensity, i.e. the fraction of genera that are present in each interval of time but do not exist in the following interval.

The causes and effects of these mass extinctions differ, but each seems to be explained by a turbulent period of environmental destruction.

The most famous mass extinction is undoubtedly the end-Cretaceous event (66 million years ago) that killed off the dinosaurs and vaulted the mammals to dominance. This was certainly caused in part by a large asteroid or comet impact, perhaps facilitated by extensive volcanic eruptions that had previously weakened ecosystems.

The largest mass extinction, in which up to 95% of all species went extinct, happened nearly 200 million years earlier at the end of the Permian (252 million years ago). This seems to have been triggered by some of the largest volcanic eruptions in Earth history (the Siberian Traps), which set off a destructive cascade of warming temperatures, acid rain, ocean acidification, and ocean anoxia.

The major lessons from the fossil record are that mass extinctions can happen suddenly, with little warning, when the Earth system is thrown out of balance by unlikely events like an asteroid impact, extreme volcanism, or climatic warming. Singular events can often cause domino effects of devastation that last for millions of years. Dominant groups like the dinosaurs can go extinct, and groups living in the shadows can get an opportunity to diversify. Ecological and environmental norms that had persisted for millions of years can be lost in a geological heartbeat, replaced by new types of environments, ecosystems, evolutionary systems, and Earth-biosphere interactions.

We are currently in the midst of what may be a sixth major mass extinction, caused by human-induced climate and environmental change. Understanding the causes, effects, and recoveries from previous mass extinction holds the key to better preparing for, and hopefully preventing, a modern mass extinction. The fossil record is our only ?natural experiment? showing how real organisms and ecosystems have responded to mass extinctions in the past.

In Edinburgh, faculty of the School of GeoSciences are actively researching some of the major mass extinctions in Earth history, and trying to better understand their causes and consequences.

People

Dr Stephen Brusatte (GeoSciences, UoE) studies the end-Permian, end-Triassic, and end-Cretaceous extinctions and their impact on terrestrial environments.

Prof Rachel Wood (GeoSciences, UoE) is studying the causes of the end-Permian extinction and its effects on marine ecosystems and the global carbon cycle.

Prof Dick Kroon (GeoSciences, UoE) is a leading expert on the end-Cretaceous extinction and how this impacted global temperatures, marine environments, and the carbon cycle.