Book Review: Extinct: Dunkleosteus

Extinct: Dunkleosteus (Extinct - The Story of Life on Earth Book 2)  

By Ben Garrod

2021: Zephyr, 114pp.

This book for grade schoolers by Ben Garrod is part of a series on extinct animals. It’s also the first book of any type devoted to Dunkleosteus, as far as I can tell. Fortunately, it's a terrific book, well written, current, and gorgeously illustrated. Garrod is a TV science personality and a professor of Evolutionary Biology and Science Engagement at the University of East Anglia.

He opens with an explanation of extinction and how it appears in the fossil record. The next chapter discusses the reasons a species may go extinct, starting with the usual suspects like competition but including coextinction, genetic mixing, and climate change (natural and otherwise) and discusses the phenomenon of mass extinctions.

After this material covering the purpose of the series overall, Garrod homes in on the Late Devonian extinction. He explains the distinctness of this event lies in having multiple causes over time. The Late Devonian is blamed on a mix of dropping oxygen levels, warming, rising seas, and a global algal bloom.

Halfway through the book, we get to the Dunk itself. Garrod takes readers through the discovery, naming, and features of D. terrelli. He discusses the challenge of figuring out bite force, not just in an extinct animal, but in living ones.  The author vividly describes the sucking/grabbing feeding motion of the multi-jointed skull as the Dunk “throwing its entire face forward.” Then he presents something that, for all my time reading on this species, I’d missed: that we have a fossil showing much of the pectoral fin (Carr, 2010) and the fin rays. Garrod agrees with the 2017 paper showing the tail was more shark-like than in many reconstructions. 

Garrod gives good descriptions of many other topics, including where Dunk and the placoderms fit in evolution, how many Dunk species there were, its food supply and environment, and so on. He explores possible behavior, including comparisons to modern predators. The oceanic whitetip shark, an open-water hunter, is his preference. He notes how cannibalism is hinted at by damaged armor plates but not yet proven, and he closes with a short glossary.

There aren’t many nitpicks to make about this book. Given the audience, the text is relatively sophisticated yet very clear throughout. (While he mentions live birth, the topic of the placoderms inventing intromittent sex is passed over.)  The book reflects the latest science. Garrod probably repeats the “apex predator” bit more than necessary, and he doesn’t include any suggestions for further reading or viewing (not that there is much for this age group). This is a great book for the curious young reader, and the curious adult reader will get a lot out of it, too. 

Gabriel Ugoieto contributes the wonderful color illustrations.