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Vast new fossil record challenges story of Earth’s ‘big five’ mass extinctions
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Ammonite fossils preserved in limestone. Such fossil deposits help scientists to understand biodiversity over Earth’s history.Credit: Herve Conge/Science Photo Library
Large language models (LLMs) such as OpenAI’s ChatGPT are trained to recognize patterns in written texts, helping them to choose a statistically probable word to complete a sentence. Palaeontologists have now trained a similar model on fossil records instead of words, then used it to reconstruct a timeline of changes in Earth’s biodiversity over hundreds of millions of years in unprecedented detail.
This big-data approach to interpreting the rock record — the field known as stratigraphy — could spur a rethink of major upheavals in the history of life, the model’s developers say. For instance, the model suggests that three of the “Big Five” mass-extinction events were gradual declines in biodiversity, rather than the sudden cataclysms described by other reconstructions.
Supercomputer scours fossil record for Earth’s hidden extinctions
The model is “a real revolution for studying stratigraphy and past diversity change”, says Shuzhong Shen, a palaeontologist at Nanjing University in China, who presented the research at a meeting of the Geological Society of America in Denver, Colorado, on 12 October.
Other researchers say that although the model’s reconstruction — called OneStrata — seems to be the most detailed global record so far, scientists already have high-resolution reconstructions of changes in biodiversity at specific locations, including many that shed light on mass extinctions.
“We could do some extra things with it, but I don’t know if it would be Earth shattering,” says Matthew Clapham, a palaeontologist at the University of California, Santa Cruz.
The history of life is written in the fossil record. Researchers can reconstruct the grand story of adaptation and extinction across Earth’s history by marking the depth at which species occur in layers of sedimentary rock, called strata; depth corresponds to when a fossil was deposited in geological time. However, it is a steep computational problem to combine sequences from many different sites involving tens of thousands of species into a single coherent timeline of changing biodiversity.
To simplify this task, stratigraphers divide sequences of fossils for each species into time intervals of millions of years. This makes it easier to assemble many sequences into a unified whole. But it produces a blurry view, obscuring changes in biodiversity that occur over shorter time intervals.