Michael J. Benton (Thames & Hudson)
鈥淒O YOU guys ever think about dying?鈥� blurts out Stereotypical Barbie, horrifying her friends and kicking off Greta Gerwig鈥檚 Barbie movie. Maybe she had just read Extinctions: How life survives, adapts and evolves, an account of the worst calamities to have befallen life during the past billion or so years.
For a book that is essentially a catalogue of mass death, it is a remarkably breezy read. This isn鈥檛 surprising, given Benton has written a string of books for general audiences. His day job, however, is as a palaeontologist at , with much of his career spent studying the evolutionary history of major animal groups and the impacts of mass extinctions.
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His latest book is a chronological history of those extinctions, moving from the deep past to the present. Its focus is on those that affected animals, which means it is all about the past 600 million years or so.
Earth鈥檚 earlier history was dominated by microbial life, and Benton largely skips over this because we know very little about extinction events in those shadowy periods. It seems likely the rise in atmospheric oxygen and the Snowball Earth episodes, when much of the planet froze over, caused microbial die-offs, but, so far, we haven鈥檛 found direct evidence in the fossil record.
Instead, Benton鈥檚 story begins in the Ediacaran, the period between 635 and 539 million years ago. The Ediacaran rocks preserve the oldest evidence of animal life. Much of it is deeply strange to our eyes, such as frond-shaped organisms that look like the leaves of ferns but turn out to be animals.
As the Ediacaran transitioned into the later Cambrian, many of these organisms disappear from the fossil record. Benton calls this mass extinction 鈥渙ne of the most significant that Earth has seen鈥�, because it led to the origin of recognisably modern animal groups like arthropods (the group that includes insects). But there is no smoking gun 鈥� no sign of an asteroid impact, for instance 鈥� so Benton suggests that newer animal groups might have outcompeted the Ediacarans.
Moving forward in time, Benton alternates between familiar and unfamiliar stories. Many readers will know about the end-Permian extinction, in which between 90 and 95 per cent of species died out, and the end-Cretaceous extinction, in which an asteroid strike took out all the dinosaurs except birds.
For these oft-told tales, Benton reaches for novel angles. His account of the end-Permian extinction begins on the Russian steppe, where palaeontologists have identified traces of 鈥渧iolent rainfall, erosion, terrifying water flows and an enormous transport of rocks鈥�. For the dinosaur extinction, however, he focuses on the Tanis fossil deposit in North Dakota, which purportedly preserves animals caught in a flash flood triggered by the asteroid 鈥� in other words, animals that died on the day of the impact.
He mentions lesser-known events, too. Benton highlights the Carnian Pluvial Episode, a period of climate change that took place 232 million years ago, early in the dinosaur era. In the 1980s, geologists Mike Simms and Alastair Ruffell identified these climatic shifts and tentatively linked them to marine extinctions. At the same time, Benton, then a graduate student, found evidence of a smallish mass extinction among land-dwelling vertebrates.
It is a fascinating story of how science advances in fits and starts, with the punchline that the Carnian Pluvial Episode helped drive dinosaur evolution by clearing the decks for them.
Benton鈥檚 take-home, that extinctions can also be creative events because they pave the way for new organisms, is a little well-worn. It is also only comforting from a geological perspective: as Benton makes clear, living through a mass extinction would be a slog. (Good thing we aren鈥檛 causing one, eh?)
If there is a fault with this book, it is that there isn鈥檛 quite enough novel material like the Carnian story for those (like me) with a strong interest in palaeontology. Nevertheless, most readers are likely to be enthralled. Extinctions is fast-paced, clear and doesn鈥檛 skimp on the drama. If the Tanis site, with its extraordinary fossils, is news to you, there are plenty more wild tales to enjoy.
Michael Marshall is a writer based in聽Devon, UK
