How Fast Did T. rex Run?: Unsolved Questions from the Frontiers of Dinosaur Science

Book Preface

Consider the TYRANNOSAURUS rex. This most iconic of dinosaurs is the superstar of movies, features in endless documentaries and appears in every popular book of dinosaurs (generally on the cover) that one could imagine. In your mind’s eye, I’m sure there’s already a clear picture of this incredible animal and if you know a bit about it, you probably have some details down about it, too. You may perhaps have an idea of its length, weight, height, number of teeth or top speed; if you are particularly keen, you may know of its bite power, skin texture, habitat, favoured prey species, and more.

Much of this, you may imagine, is based on some rigorous science and fossil data, or at least as rigorous as it can be, given that the last Tyrannosaurus died in the great mass extinction of the dinosaurs some 65 or so million years ago. Hundreds of papers in the scientific literature have described the sizes and shapes of bones, reconstructed the cartilage of the joints, worked out which muscles would attach where on the skeleton, identified patches of fossil skin, looked at footprints and bite marks on bones, calculated mass estimates and walking speeds, and more. We can put together a remarkably detailed picture of this animal.

More than that, in fact, we can delve into some incredible features of which even fans of dinosaurs would likely be unaware. We can look inside the skulls of Tyrannosaurus specimens to see how large the various parts of their brains were, and we can get an estimate of their range of hearing from the structure of the inner ear. There have been studies looking at pupil shape of the eyes, nocturnal versus diurnal habits, growth rate, the sex of individual animals, and how far on aver-age they would have to travel to find food when scavenging.

Putting all of this together gives us an unparalleled picture of an animal that has been extinct for a million human lifetimes. We know how fast did T. rex run?
more about Tyrannosaurus than perhaps any other extinct dinosaur,* but we have only around twenty-five good skeletons to work from, and this creature is just one of some 1,500 or so dinosaur species currently known to science.

Even for the things we do know, we can’t compare many of these facts to other species that the Tyrannosaurus lived alongside, or that came before it. Yes, it’s amazing to have good estimates of the speed of this huge carnivore, but it is also frustrating to be unable to answer questions such as ‘could it catch Triceratops?’ when we don’t know how fast they were. Furthermore, our knowledge of rexy is still full of huge holes – we don’t know what colour it was or what its eggs or nests looked like. We don’t know if it lived in groups, if it mated for life, if it preferred forests or open environments, or if it migrated in winter. For all our technological advances, and two centuries of new data and ideas, we still know less than the basic ecologies of living beings: what parasites and diseases afflicted them, how they commu-nicated, if they ever took fish as prey, what their internal organs were like, or even what their tiny arms were used for.

Whenever I do some kind of outreach or public engagement with science, I encounter things about dinosaurs that the public are abso-lutely amazed to learn scientists know with certainty, and also things they assume would be easy to work out, for which we have no real idea of the answer. It’s a curious quirk that there is such a disparity between what palaeontologists do know and what many people think we know. This book is, therefore, ultimately about what we don’t know about dinosaurs.
There are major gaps in our knowledge, but extraordinary advances in palaeontological methods and ever more dinosaur fossils promise a landslide of new data and huge leaps forward in our understanding of these incredible creatures. There are a great many issues that we are currently unable to resolve, but we have tantalising hints that we may soon be able to answer them. This book aims to bridge the gap between

* The birds are living dinosaurs, something we will deal with later, but for now accept that for the rest of this book the term ‘dinosaur’ excludes the birds, unless otherwise stated. For the record, the correct technical term for what most people would call a dinosaur is a ‘non-avian dinosaur’. what we do know and what gaps there are in our understanding, but also to examine just how we are likely to fill them in the future.

Ongoing research trends, as yet undescribed specimens and still-developing techniques mean we can plot a route to the next genera-tion of knowledge of dinosaur biology. We will make mistakes in the future, and have doubtless made some in the past that have yet to be corrected, but the inexorable progress of scientific discovery will doubtless improve on what we have now.

We know enough to spot some key gaps and have the fossils to try and fill them, but there will be exciting discoveries and some most unexpected results on the way. Based on the last two centuries of dinosaurian research, that much is certain. There are also gaps that may never be filled, or, perhaps worse, we may be able to tentatively fill them, but not know if our calculated answers are correct. We have probably learned more about dinosaurs in the last twenty years than in the previous two hundred, and are poised to take many more steps forwards in the coming decade. This book will address the recent strides made and the advanced knowledge we have of these astonish-ing creatures, as well as what we hope to learn in the future about these most fascinating of extinct animals.

I’d also add that while this book has been kept as up to date as possible, the field of dinosaur palaeontology is constantly advancing and remains full of contradictions. Evidence is often tantalisingly incomplete and it can mean several ideas are near equally valid, or the weight of data hangs in the balance. I’ve tried to steer as even a course through this as possible and stick to the more mainstream hypotheses (while recognising some of the more important alternatives or contra-dictions), but it’s impossible to cover every aspect and there will be researchers who disagree most strongly in places with what I have said. Even allowing for that, there will be other issues thanks to the advances made. While writing this book, I’ve constantly had to update multiple chapters and sections, and doubtless between the time this is signed off by my editor and you read these words, a paper or two will have come out that fills a gap I claim is unfilled, or overturns a hypoth-esis I had advocated as being correct. This is inevitable, science advances after all, but be warned that for all my best efforts, this book will retain or even develop controversy as research continues.

A common accusation levelled at scientists is that they are always changing their minds, as if this is somehow a negative. The oft-rephrased (and never quite certainly attributed) quote of John Maynard Keynes is most apt: when the facts change, I change my mind. Regardless of the original source or correct wording of this statement, it is of course the correct approach to take. If old analyses are shown to be flawed or problematic, or if new data comes to light (an obviously very common phenomenon in palaeontology), then the weight of evidence can shift.

Given the huge gaps in our knowledge of dinosaurs, it should be little surprise that the weight of evidence will often shift (and on occasion lurch back again) on key subjects, even some where we thought we were confident about the results. It can be frustrating, but it is a sure sign that we are learning and the science is getting better, not worse.