One of the many unique challenges of paleontology is that the animals you’re studying – be they dinosaurs, mammoths, or prehistoric insects – are all extinct. With no living specimens to observe, making educated assumptions about how these creatures lived, loved, fought, and fed can be especially difficult. It’s these kinds of mysteries which lie at the heart of University of Manchester paleontologist Dean R. Lomax’s fascinating and highly recommended new book, Locked in Time: Animal Behavior Unearthed in 50 Fossils (Columbia University Press, 2021).
While one might assume the best way to learn about prehistoric animal behavior is to study their modern descendants, Lomax points out the limitations of this approach. Birds might be living dinosaurs, but no amount of time spent looking at a robin is going to help you understand a giant, long-necked sauropod like Diplodocus. For Lomax, the key to unlocking the behavior of prehistoric animals is, not surprisingly, in their fossils. This includes both the fossilized remains of the creatures themselves, as well as trace fossils (or “ichnofossils”) like footprints and feces.
Knowing that sex sells, Lomax starts Chapter 1 of Locked in Time with the topic of sex and reproduction. Considering how rare it is to find complete fossils, let alone articulated ones, I was surprised to discover that we have any fossils at all showing animals in mid-coitus, let alone upwards of 50 (!), and that nearly all of them are of invertebrates (!!). Though Lomax does end this section with a pair of turtles forever locked in an amorous embrace.
Chapter 2 looks at parental care and signs of communal life among prehistoric animals. One of the most fascinating fossils examined here is a Psittacosaurus nest containing nearly 30 juveniles and one sub-adult. Lomax speculates that the presence of an adolescent Psittacosaurus, which had not yet reached sexual maturity, could indicate that this animal was serving as a “babysitter” for the juveniles while the parents were off foraging for food.
This leads into Chapter 3, which deals with fossil evidence of migration and home-building. Locked in Time looks at fossil tracks and discusses how the footprints of the massive Chinese sauropod, Mamenchisaurus, could become death traps for much smaller dinosaurs like Limusaurus and the primitive tyrannosaur Guanlong. Fossils of both of these dinosaurs have been found inside Mamenchisaurus tracks, showing evidence that they became mired in these behemoth’s footprints once they began to fill with rain and mud.
Lomax discusses another fascinating ichnofossil, a pair of theropod footprints and an accompanying imprint of the same dinosaur’s cloaca, found in Massachusetts. The ground around them shows possible evidence of rainfall, suggesting the animal may have been hunkered down and waiting out a Jurassic downpour.
Chapter 4 of Locked in Time, examining evidence of combat and predation, is also certain to be popular. Despite the prevalence of dueling dinosaurs in popular culture, fossils of dinosaurs locked in mortal combat are virtually nonexistent. The most famous exception is the fossilized remains of a Protoceratops and a Velociraptor discovered in Mongolia in 1971. This now-iconic fossil shows the Protoceratops with its beak locked on one of the Velociraptor’s forearms, while the raptor strikes at the Protoceratops’ neck with its left leg and signature sickle-shaped talon.
In sharp contrast to the scarcity of fighting dinosaur fossils, the number of fossils showing animals who died with their last meal still in their belly is absolutely prodigious. Among the most amazing is what Lomax refers to as a “fossil doll” (in reference to Russian Matryoshka dolls), in which the remains of a snake were found with a lizard in its gut, while the lizard has a preserved beetle in its own stomach!
The last chapter of Locked in Time deals with fossils of dinosaurs and related animals that died while suffering from disease, parasites, tumors, or broken bones. It also looks at possible ichnofossils of dinosaur urine and flatulence, which is sure to delight any 8-year-olds whose parents decide to read them the book.
While much of this behavioral analysis may sound rather definitive, Lomax is careful to note that despite decades of research, some aspects of ancient animal behavior are likely to always remain purely speculative. A set of provocative scratches from the Cretaceous period, for example, could be evidence of theropod dinosaurs performing mating dances like modern birds, but we’ll probably never know for sure.
Likewise, Lomax also takes several opportunities throughout the Locked in Time to stress the importance of science’s willingness to change its views based on new data. To illustrate this, he relates the famous story of how the first Oviraptor skeleton was found atop a clutch of eggs. Paleontologists originally assumed that the animal was robbing the nest (hence the name, which means “egg thief”), but subsequent analysis showed that the eggs contained baby Oviraptors, meaning this was likely a mother protecting her young and not a predator looking for breakfast.
Locked in Time features copious photographs of the fossils discussed, plus accompanying illustrations by paleoartist Bob Nicholls. Unfortunately though, all of these are in black and white. This is my only real complaint about the book, as color images would have definitely been appreciated. Nevertheless, even in black and white, Nicholls’ work is striking. Worth singling out simply for their unusualness are his drawings of a female Maiacetus (or “walking whale”) giving birth, and his rendition of a carnivorous Entelodont (or “hell pig”) swallowing a fledgling camel whole.
Locked in Time is written for a general audience of paleontology enthusiasts, and avoids technical jargon. While not a children’s book, a smart middle-schooler could undoubtedly handle it — the book is relatively short at 286 pages, including an index. Citations for sources are restricted to a “Further Reading” section in the back, which is fortunately divided by chapter and topic to make finding additional information easy.
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