As its title suggests, The Rise and Fall of the Dinosaurs is the story of the 186-million-year reign of the dinosaurs on earth, from their origins following the Permian-Triassic extinction to the demise of the non-avian dinosaurs at the Cretaceous–Tertiary boundary 66 million years ago. Author Steve Brusatte, a paleontologist at the University of Edinburgh, weaves the dinosaurs' story together with the story of his own journey from dinosaur-obsessed teen to prominent paleontologist. Along the way we meet many very colorful characters who have contributed to our understanding of the dinosaurs' story, some of them historical figures and others contemporary colleagues of Brusatte who have made significant discoveries.
Brusatte is a gifted storyteller and explainer of complex ideas, making this book a very enjoyable read. He presents paleontology as a vibrant field of inquiry, with new dinosaur species being discovered at a rate of about 50 per year. There are stories of expeditions in the field, but we also meet paleontologists who work in the laboratory using high-powered microscopes, CAT scanners, computer models, statistics, and experimental methods to investigate the dinosaurs. Along the way Brusatte provides clear and concise explanations of relevant biological concepts including natural selection, descent with modification, biological diversity, speciation, cladistic analysis, niche partitioning, and island dwarfism.
Among the highlights for me was the chapter on the evolution of birds, the only dinosaurs to survive the Cretaceous–Tertiary mass extinction. Birds evolved from theropods – bipedal dinosaurs with hollow bones, highly efficient lungs, three fingers on the hand, and three weight-bearing toes on the foot. Well-known examples include Velociraptor and Tyrannosaurus rex.
The dinosaur origin of birds was first proposed by T. H. Huxley following the discovery of Archaeopteryx in 1860 but was largely dismissed. Huxley's proposal was resurrected by John Ostrom in 1969 following his discovery of the theropod raptor Deinonychus. Ostrom's proposal also faced opposition, but subsequent fossil discoveries have provided incontrovertible evidence. The logic of Huxley's and Ostrom's argument rests upon our understanding of biological reproduction, Darwin's theory of common descent, and the empirical evidence from the fossil record, which demonstrates anatomical similarities between birds and dinosaurs. The strongest fossil evidence supporting the dinosaur origin of birds comes from a collection of fossils found in Liaoning Province, China. Brusatte puts it thus: “The Liaoning fossils sealed the deal by verifying how many features are shared uniquely by birds and other theropods: not just feathers, but also wishbones, three-fingered hands that fold against the body, and hundreds of other aspects of the skeleton. There are no other groups of animals – living or extinct – that share these things with birds or theropods: this must mean that birds came from theropods. Any other conclusion requires a whole lot of special pleading” (Brusatte, 2018, p. 282).
Critics of evolution may claim that it is improbable that the set of complex features necessary for flight – feathers, wings, wishbone, hollow bones, efficient respiratory system – could arise all together, at one time, to produce radically new animal forms, like birds, who are so well adapted for flight. But the fossil record shows us that each of these adaptations evolved independently in different species, and each may have served a different function than the role it plays in flight. For example, feathers, a feature most often taken to be characteristic of birds, were present in non-avian dinosaurs whose forelimbs could not possibly have generated enough lift for flight. The evidence suggests that feathers originally evolved for thermoregulation and/or display.
The evolution of birds also illustrates the fact that evolution is not progressive, or forward-looking. Neither birds, nor human beings, nor any other species for that matter, is part of some overall “plan” of evolution. Brusatte writes, “During the tens of millions of years that dinosaurs were evolving the signature features of birds one by one, there was no long game, no greater aim.… Evolution works only in the moment, naturally selecting features and behaviors that make an animal successful in its particular time and place. Flight was something that just kind of happened when the time was right” (p. 300).
Finally, bird evolution also illustrates a curious feature of the process of speciation: one cannot tell that it is occurring at the time that it occurs. A fully fledged bird did not just pop out of one dinosaur's egg one day long ago. Even if scientists had been present in the distant past, some 150 million years ago, they would not have been able to mark the exact moment when the first bird arose. The line between bird and non-bird is blurry and, as Brusatte explains, “it's just a matter of semantics” (p. 284). A speciation event can only be crowned retrospectively, “when you discover that its sequels have a certain property” (Dennett, 1995, p. 96).
The Rise and Fall of the Dinosaurs is an excellent book that is accessible to students as well as teachers. Readers are treated to an engaging story about fascinating animals and the scientists who study them. In addition, students who read the book may learn some biology along the way.