For over 150m years dinosaurs were the dominant group of land animals, occupying every landmass and evolving into hundreds of different species. Sixty-six million years ago many of them disappeared in a mass extinction event, the cause of which is still unknown. Did death come via a comet or asteroid crashing into what is now south-eastern Mexico? Or did that extraterrestrial collision merely administer a coup de grâce to an already declining population, stressed by climate change and violent volcanic activity?
These and other questions are explored in an updated edition of “Dinosaurs” from the Natural History Museum in London. Written by palaeontologists Darren Naish and Paul M. Barrett, this is an intelligent, beautifully illustrated and comprehensive guide to all things dinosaur-related. A fascinating early section charts the history of dinosaur research from the Victorians to the present day, followed by chapters on, among other things, dinosaur anatomy, ecology and behaviour.
A detailed, in-depth read, “Dinosaurs” is better suited to the serious teenage or adult reader than the coffee table – though you don’t need any specialist knowledge to enjoy the book. It introduces to a wider audience the ideas and techniques already familiar to dinosaur researchers, from the computer models used to estimate the weight of Stegosaurus, to 3D physical models that help scientists figure out how theropods (bipedal carnivores such as Tyrannosaurus Rex) killed their prey. Elsewhere the authors discuss how immense dinosaurs such as Diplodocus managed to mate (probably briefly), the life expectancy of T-Rex (under 30 years), and why certain dinosaurs developed such showy crests, frills, plates and flamboyant feathers. Naish and Barrett believe that sexual selection trumps species identification, although they point out that the evolution of feathers may be a more complex process.
“Dinosaurs” is subtitled “how they lived and evolved”, but the use of the past tense turns out to be misleading. Dinosaurs never really disappeared. Instead, around 160m years ago, they evolved into something much more familiar. The authors write that today “we have an excellent body of evidence showing that birds are dinosaurs – not just relatives of dinosaurs or descendants of dinosaurs.” Extinct creatures such as Stegosaurus and Diplodocus should, they argue, be referred to as “non-bird dinosaurs”. Their extant counterparts now number over 10,000 different species worldwide.
Shown here clutching the immense thigh bone of an extinct moa (a giant flightless bird), this is the man who invented the term dinosaurs. In the 1840s Richard Owen concluded that three extinct reptiles from southern England shared features of the hip region that other reptiles lacked. Because these creatures were of remarkable size, Owen named them dinosaurs, often translated as “terrible reptiles" (with “terrible” implying “awesome size” or “fearfully great”). Owen later founded the Natural History Museum in London.
Allosaurus attacking a Diplodocus
Many of the most famous dinosaurs such as Allosaurus, Diplodocus (shown here) and Stegosaurus, were first discovered in western North America during the Great Dinosaur Rush of the late 1800s. During the early 20th century, however, public and scientific interest in dinosaurs tailed off. Dinosaurs were cast as dim-witted, cold-blooded creatures who were plodding towards their inevitable extinction. Inferior to the mammals that replaced them, they were considered unworthy subjects for serious study.
“The Dinosaur Heresies”
Fuelled by new evidence of complex dinosaur behaviour and biology, the late 1960s saw a so-called “dinosaur renaissance”. In 1986 American palaeontologist Robert Bakker published “The Dinosaur Heresies”, recasting the dinosaurs as a spectacular success story and influencing the modern generation of dinosaur experts. Since the sixties vast numbers of new dinosaurs have been documented, and an incredible 85% of all recognised non-bird dinosaurs have been named since 1990. China, Mongolia and Argentina are current hot-spot discovery sites.
Scientists trying to understand dinosaur anatomy and behaviour often study modern animals such as elephants, lizards, crocodiles and birds. In 2004 fossil hunters in China discovered the remains of an adult Psittacosaurus alongside 34 babies. Such a large number of infants suggests that this may have been a dinosaur crèche. Since many birds have systems of childcare in place, it seems they could have been present among dinosaurs too.
Thanks to improved technology, we now have a better understanding of how to “colour in” dinosaurs. Scientists working on dinosaur colour study the fossilised remains of melanosomes, microscopic structures that contain the pigments responsible for giving some animals their colouration. Different shapes of melanosomes are linked to different colours: round shapes give brown or red shades, whereas sausage-shapes give black or grey. In 2010 the small Cretaceous dinosaur Sinosauropteryx was one of the first to be “coloured in” using this technique.
This enigmatic painting shows Tianyulong, a recently discovered dinosaur from China. Created by palaeoartist Robert Nicholls for the jacket of this new edition of “Dinosaurs”, it’s an attempt to move away from what he describes as clichéd images of “roaring dinosaurs”, one of which was on the cover of the previous edition. Palaeo-art is evolving alongside new discoveries in palaeontology. “I wanted to redefine what people think of as a dinosaur,” Nicholls said in an interview, “so it’s more birdlike, more unusual, less scaly. Dinosaurs were animals, not movie monsters.”
Dinosaurs: how they lived and evolved Darren Naish and Paul M. Barrett (Natural History Museum)