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

by david hone
princeton university, 
280 pages, $29.95

Sometime in the mid-­seventeenth century, in a quarry in Cornwell, someone found a piece of a much bigger world. It was a bone, the lower part of a thighbone, and it looked almost exactly like the femur of a man. But this bone was enormous: At its widest point, it was two feet across.

The specimen ended up in the hands of Robert Plot, Oxford’s first-ever professor of chemistry and (later) secretary of the Royal Society. In his 1677 The Natural History of Oxford-shire, Plot devotes quite some time to this huge oddity. First, he rejects the idea that this is just a piece of rock that happens to resemble a bone. Where the bone had been broken off, you could see the hollow and the imprint of the marrow inside, its “shining Spar-like Substance.” There were all the anatomical features you’d expect, rendered in far too plausible ­detail: “The capita Femoris inferiora, between which are the anterior and the much larger posterior Sinus, the seat of the strong Ligament that rises out of the Thigh, and that gives safe passage to the Vessels descending ­into the Leg.” This bone had once belonged to a living creature. But with “both Horses and Oxen falling much short of it”—which?

Some of Plot’s learned colleagues advanced the idea that it could have belonged to an elephant, perhaps “brought hither during the Government of the Romans in Britain,” but Plot had his doubts. There was no record in the Latin histories of any elephant being brought to this cold, distant island. What’s more, “there happily came to Oxford while I was writing of this, a living Elephant to be shewn publickly.” Plot examined the poor waylaid creature and discovered that its thigh looked nothing like the one in his possession. In the end, he decided that it was a human bone after all, just from a very large human. “There have been Men and Women of proportionable Stature in all Ages of the World,” he explains, “down even to our own Days.” He lists a few. Goliath, who stood at nine feet and nine inches, and Pusio and Secundilla, alive in the time of Augustus, whom Pliny describes as being ten feet tall and whose bodies were preserved in the gardens of Sallust as a curiosity. Plot tentatively suggests an identity for the owner of this particular thighbone. Pliny also refers to “one Gabbaras by name, who was brought from Arabia by the Emperor ­Claudius; his height was nine feet and as many inches.” “I am rather inclined to believe,” Plot writes, “that Claudius brought this Gabbara into Britain with him, who possibly might dye and lay his Bones here, than that ever they belonged to any Elephant.”

The broadcaster David Kesten­baum once recorded a short segment on Robert Plot and his mysterious bone. Plot’s deduction, he concludes, really did make a lot of sense. If nothing else, “it was way more sensible than the truth.” From Plot’s description and illustrations, later researchers have identified the bone as the thigh of a Megalosaurus, a thirty-foot-long apex predator that inhabited the slightly different Cornwall of a slightly different age.

Plot’s find has entered history as the first-ever confirmed dinosaur discovery—the first time a human being brushed against one of the reptiles that once ruled our world. But there must have been others. There must be a prehistory of our encounter with the prehistoric. Plot himself talks about other strange bones dug up in the past, “such as the two Teeth taken up at Edulfsness in the County of Essex, in the Reign of King Richard the First, that might have been cut into two Hundred of an ordinary Size.” After the Great Fire of London in 1666, the ruins of St Mary Woolchurch Haw were pulled down, and another enormous thigh was found underneath. Plot also possessed an outsized tooth excavated from under the parish church of Moreton Valence in Gloucestershire. “Now how Elephants should come to be buried in Churches,” he adds, “is a Question not easily answered.” More evidence that these are human remains, not animal, unless you want to “run to so groundless a shift, as to say, that possibly the Elephants might be buried there before Christianity flourish’d in Britain, and that these Churches were afterward casually built over them.” He’s mocking, but it’s an idea I like a lot. Somehow, without knowing, we sensed that something vast and impossible was buried here, that these spots hid the remnants of a grander world, and we made them holy.

Aside from that, evidence for an early encounter with the dinosaur is surprisingly sparse. If past ­ages did dig up these creatures, they didn’t keep them. There are no ­Velociraptors in the royal collections of Europe. There were no medieval attempts to explain these things with theology, no monasteries with demons’ skulls in the crypt: three huge horns and a fern-chomping beak. But sometimes, old texts do refer to giant bones. In Herodotus, the Spartans under Anaxandridas consult the Oracle of Delphi for advice on their war against Tegea; she tells them to send some men into Tegean territory and “bring back the bones of Orestes, son of ­Agamemnon.” When they find ­Orestes’s bones, the skeleton is twelve feet tall. As we know, some dinosaur bones can be easily mistaken for giant versions of our own. But it’s hard to say for certain whether they’d dug up a dinosaur and named it Orestes, or whether the huge size was just a way of expressing Orestes’s mythic stature. In the Museum of Fine Arts in Boston, there’s the Hesione vase, a piece of black-figure pottery from the sixth century b.c. that shows Hercules fighting a sea-monster outside Troy—but in this version the sea-monster is a white skull, leering and reptilian, that seems to emerge directly out of the black rock face. A few theorists have identified it with the extinct miocene giraffid Samotherium, or a giant prehistoric monitor lizard, or maybe, just maybe, a dinosaur.

Almost every human society had some kind of dragon-myth. Many people tend to assume that this commonality must have something to do with the dinosaurs, and some Chinese sources seem to bear this out. The Cheng Han Dynasty historian Chang Qu describes a mountain in Wucheng County from which dragon bones are sourced. “It is said that dragons flew up from these mountains, but when they found heaven’s gates closed, they could not enter, and thus fell dead in that place, and later sank into the earth. That is why one can dig out dragon bones.” But when they were uncovered, these dragon bones were often ground into a powder and used as medicine, which makes them hard to analyze. A few fragments do survive: In the nineteenth century, European paleontologists bought up caches of dragon bones from Chinese pharmacies to search for fossils. And they found them. The dragon bones were Pleistocene mammals, creatures from the last two million years: fossil horses, giraffes, deer, elephants, and even other hominids. (The bones of ­Peking Man, Homo erectus pekinensis, were first found in a place known as Longgushan, or Dragon Bone Hill.) But no dinosaurs.

Admittedly, Chinese dragons are not just large reptiles. In some myths, the entire earth is a dragon, and the mountains are the scales on its head. There are celestial dragons whose bodies carry the heavens above the sky. Still, I like to believe that someone, maybe thousands of years ago, uncovered one of the late rulers of our planet, and understood how deep the chasm of time we’re sitting on top of really is.

Really, it’s astounding that we’ve discovered any dinosaur bones at all. For any land animal to survive as a fossil for tens or hundreds of millions of years—and for human beings then to find it—is practically a miracle. Twenty years before Robert Plot, Sir Thomas Browne wrote about another discovery: a few dozen ­Anglo-Saxon burial vases found under the soil in Norfolk. “The treasures of time lie high,” he wrote, “in Urnes, Coynes, and Monuments, scarce below the roots of some vegetables.” A thousand years settles only a few inches of soil. Once you slip out of historical time, though, things get tricky.

Fossilization is fairly simple for marine organisms. A dead creature sinks to the bottom of the sea, where it’s slowly covered by sediment that’s eventually compressed into rock. The world is full of these things, which is why you can buy an ammonite fossil—the actual remains of a creature that might have lived three hundred million years ago—for less than the price of a supermarket sandwich. But the land is sheer chaos.

When a creature dies under the open sky, its remains are likely to be torn apart by scavengers, who may scatter its bits over a radius of several miles. Bones are gnawed into chunks, and chunks are eroded by wind and water. A bone buried under the soil will be slowly cracked apart by roots. Almost everything that has ever lived on land ends up as mulch and dust. It has to be this way; otherwise, the entire world would be a charnel house. But even if an intact skeleton does end up safely buried where nothing can get at it—in a flood, or under a rain of volcanic ash or the desiccating dunes of a desert—its preservation isn’t assured.

Our earth is a storm in very slow motion. As they pile on top of each other, layers of stone distort and deform the bones locked away inside. The processes that create metamorphic rock will utterly destroy any fossils. Slabs of the earth collide with each other, churning into mountain ranges. Deep crust boils to the surface; newer layers slip ­underneath. Between the day it was attached to a living creature and the day it made the journey from ­Cornwell to Oxford, Robert Plot’s mysterious thighbone had to endure 166 million years in the depths of the earth.

And then, of course, this two-foot-wide fragment of the Middle Jurassic had to be found, somewhere in an entire planet’s worth of subsurface. (Imagine losing your keys, and then finding them again, buried in rock, after hundreds of millions of years.) But even once a bone’s been exhumed and brought out into the light, it’s still in danger. During the Second World War, a British bombing raid over Munich destroyed the first known Spinosaurus skeleton. For their part, the Luftwaffe pulverized the tiny ­Thecodontosaurus—one of the oldest known dinosaurs, and a possible ancestor of the enormous sauropods—in Bristol. These bones had survived intact for two hundred million years, but they couldn’t make it through the 1940s. Or sometimes they can just vanish. We have Robert Plot’s illustrations of his Megalosaurus, but not the bone itself. It’s lost with the rest of his geological collections. Perhaps it’s still around, somewhere, in some dusty hole, waiting to rise again.

Almost everything we know about dinosaurs has come from these chance finds, and even once the bones were properly identified we continued getting things wrong. Crystal Palace Gardens in South London is still populated by the enormous concrete dinosaurs sculpted by ­Benjamin Waterhouse Hawkins in 1854. In the mid-nineteenth century, the dinosaur was a uniquely modern creature, scientific and progressive, a brand-new animal untouched by the human past, dragged into our awareness by human reason and industry. No wonder dinosaurs were chosen to decorate the Crystal Palace, site of the Great Exhibition, a huge glittering celebration of British world supremacy. But if you go to see them now, they’re barely even recognizable as dinosaurs. They look like enormous crocodiles: Hawkins’s creatures sprawl, with their fat ponderous bellies, their sagging posture, their slow and stupid eyes. At the time, the best scientific understanding was that dinosaurs really were just giant lizards. Most famously, Hawkins gave his Iguanodon a horn on the end of its nose. Now we know that Iguanodon was at least partially bipedal, and the horn was actually the creature’s thumb.

Since then, there’s been a fairly consistent trend: Dinosaurs keep getting lighter, sleeker, and more streamlined. They look less like crocodiles, and more like the actual living dinosaurs that surround us, which we call birds. Increasingly, ­reconstructions show dinosaurs with feathers, which is more scientifically accurate but still seems to upset a lot of people, who appear to see it as a kind of betrayal of the dinosaurs of their childhood. In the middle of the twentieth century, a dinosaur was a lean, sinewy, deadly roaring lizard. Now it’s been made softer, more pillowy—­emasculated, like some kind of Woke non-binary comfort theropod.

But our idea of what dinosaurs looked like always seems to be partially informed by culture. I still remember visiting London’s Natural History Museum as a young child, and knowing that the dinosaur skeletons there had been arranged wrong. For a very long time, bipedal dinosaurs were depicted in a “kangaroo pose,” with their spines erect and their tails dragging along the ground. Four-legged dinosaurs likewise had dragging tails; a long-necked sauropod would be followed by about forty feet of useless lizardy appendage. I was an obnoxiously precocious kid, and I’d read all the appropriate literature. At every giant fossil, I’d explain to everyone in earshot that, actually, dinosaurs weren’t like this at all, and the tail of Dippy the Diplodocus should be whipping elegant circles in the air.

And you can even construct a cultural ­theory of why people got it wrong for so many decades. In the progressive twentieth century, we wanted to believe that dinosaurs were slow and primitive; that the whole vast span of evolutionary history, culminating in human beings, was the process of getting your tail out of the muck. (Sauropod necks, too, would droop very close to the ground, as if to emphasize that this was a very stupid animal, humbled before the humans that had ­rearranged it.) Now, after the end of history, we’re less sure of ourselves. We’re starting to think that the distant past might have been less half-formed than we thought.

At the time, I didn’t question how exactly we knew that this image of dinosaur posture was the correct one and the tail-dragging version was wrong. After all, these are just two different arrangements of the same pile of bones. Nobody has ever actually seen a dinosaur wandering around, and nobody ever will. Why are we so certain that the Crystal Palace dinosaurs are wrong? Or that the images in museums today are closer to the truth?

Is it all just fashion and culture? Not entirely. David Hone explains: “We know that tails did not drag, because their muscles are arranged such that the tail would be held off the ground, and in the case of the ornithischians, the spine also had numerous ossified tendons gluing the bones together, which would have made the tail relatively stiff and straight.” We don’t have any muscular tissue from dinosaurs, but we do know where it would have been, thanks to something called the femoral fourth ­trochanter: a small nub of bone on the upper thigh that connects to the caudofemoralis, the large bulging muscle that allows a long, straight tail to be swished from side to side. Mammals, with their short drooping tails, don’t have a femoral fourth trochanter. Lizards like the Komodo dragon, with tails that drag along the ground, don’t have one, either. But crocodiles do, and so do birds (although theirs is tiny), and so, prominently, do dinosaurs.

David Hone is a paleontologist, a senior lecturer in zoology at Queen Mary University of London, and an enthusiastic advocate for dinosaur science. He wrote regularly about dinosaurs for The Guardian; he blogs about dinosaurs; he goes on TV to talk about dinosaurs; he records a podcast about dinosaurs called Terrible Lizards with the BBC’s Iszi ­Lawrence. He’s also written two books about dinosaurs for mass audiences: The Tyrannosaur Chronicles in 2016, which tries to sum up the best current scientific understanding of possibly the most charismatic of the dinosaurs, and last year’s How Fast Did T. rex Run?

Despite the title, How Fast is not a book in which the author uses the latest ­science to talk about dinosaurs; it’s a book in which he uses dinosaurs to talk about science. It’s a story about knowledge and how we came to understand so much about the world. Three hundred fifty years ago, Robert Plot could hold a dinosaur bone and have absolutely no idea where it came from, despite all his honest and laudable efforts to crack the case—because he stood near the beginning of real scientific knowledge. Today, we sit on a much bigger pile of understanding, and we can know a surprising amount.

This knowledge production can be very impressive. With modern techniques, we can wring some startling new information from the same bones that have been studied for well over a century. The first Diplodocus was found in 1877. It has since become one of the canonical dinosaurs, the ones every child knows. It’s in Fantasia and The Land Before Time; for generations, it greeted millions of children in the main hall of the Natural History Museum. But now we know how it moved. Electron microscopes can be used to check fossil teeth for tiny dents and scratches in the enamel, known as “microwear”; this information can give some clues as to the last thing a dinosaur ate before it died. But when paleontologists examined Diplodocus teeth, they noticed that they had massive amounts of microwear on the inside of the teeth, and almost none where you would expect it, on the top and the outside. “This is interpreted,” Hone explains, “as them feeding by taking small branches and fronds into their mouth and then dragging the head back so that the leaves would be stripped off. That action would mean the majority of the work, and therefore the wear, took place on the back of the teeth.” With computer modeling, you can simulate this kind of movement, move the bones around with digital muscles. The head-dragging motion works. We can reconstruct the precise motions of a creature that died 150 million years ago from nothing more than its bones.

Sometimes our knowledge is based on very lucky finds. Occasionally, fossils turn up that contain more than bones: the imprint of a dinosaur’s feathers, or the contents of its stomach, or small clues of soft tissue. Many hadrosaurs had long, bony crests on their heads, but Edmontosaurus didn’t. Still, Hone informs us, a recent specimen found in Canada was unearthed complete with “a form of fleshy cockscomb on the top of the head composed entirely of skin.” Scipionyx is known only from a single fossil, but it’s an incredible one: The juvenile dinosaur was buried in mud, which flooded its gastric tract; when the flesh rotted away, it left a perfect imprint of its internal organs. We can plot the exact path of its intestines; there are even some traces of muscle tissue and blood. In Colorado, scientists found some fossilized scrapes in the soil that appear to have been made by large dinosaurs; the current working ­theory is that, like many modern birds, mating pairs of dinosaurs might have done little ritual courtship dances with each other. If more of these are found, we might even be able to piece together the precise choreography of a dinosaur’s dance.

Maybe my favorite example is the prehistoric bird Vegavis, which lived for a few million years before the extinction of the non-avian dinosaurs. One Vegavis specimen was found with its syrinx—its ­voicebox—intact. The syrinx was digitally scanned and compared to those of living birds and crocodiles; it seems that Vegavis made a gooselike honk. Its exact relation is disputed, but Vegavis appears to be a very early ancestor of modern ducks and geese. There’s something wonderful about that image: tyrannosaurs and triceratopsids doing battle in some deep primeval landscape, with volcanoes bursting on the horizon—but in a nearby pond, the geese are still honking contentedly to each other, exactly as they do now, with that faint amusement still wobbling in their deep black eyes.

Hone is a scientific optimist. “We have probably learned more about dinosaurs in the last twenty years than in the ­previous two hundred, and are poised to take many steps forwards in the coming decade.” Yes, there are things that make the deep past difficult to understand. Hundreds of species are known only by a single isolated bone. Small dinosaur fossils are less likely to survive than big ones, so our samples are weighted towards the giants (which were, we can safely assume, rarer than the smaller ones). Many of the fossils we have come from mass-mortality events such as floods and volcanic eruptions, so it’s hard to get a real picture of ordinary life a hundred million years ago. Still, almost every chapter ends on the same hopeful note: There are gaps in our knowledge, there are still plenty of things we don’t understand, but with new discoveries coming every year those gaps are closing fast.

What Hone doesn’t do at any point is explain why any of this should matter. Why should universities pour millions into closing those gaps? Why should anyone care how fast a T. rex could run? “­Many facts of dinosaur research,” he cheerfully admits, “have no direct and obvious consequences for other branches of science.” Learning how Diplodocus ate won’t help cure cancer, mapping the fleshy frills on an Edmontosaurus won’t give us clean energy, and reproducing the noises of long-­extinct birds gets us no closer to nanosurgery or colonies on Mars. In a way, dinosaur science is the purest of the sciences, because it’s so extravagantly useless. Knowledge for its own sake, without any possible application. We learn about dinosaurs because they’re there, and learning about things is simply what science does. The relentless transformation of the unknown into the known.

And in a sense, I completely agree. Dinosaurs do not need to make any case for their importance; something so big has no use for usefulness. But this is also where we part ways. Hone is interested in dinosaurs, in part, because they show us the incredible capacities of modern science. And they do. But I’m interested in dinosaurs, in part, because they also show us its limits.

Dinosaurs are the creatures of science; they belong to science in a way most other animals don’t. Take the living dinosaurs, the birds. There is a lot of scientific knowledge about birds. We know how their wings and feathers give them flight; we’ve learned that their brains are much denser than ours, allowing a small songbird to pack in more neurons than some primates. But there are other ways of knowing them, too. You could note that in ancient Greek the word for bird was the same as the word for omen: These creatures were the world’s way of telling us about itself. In Aristophanes, birds are older than the Earth; before there were gods, birds ruled over all of creation. You could remember that for Isidore of Seville the pelican was a living metaphor for the sacrifice of Christ, or consider all the images of the Holy Spirit as a flying dove. You could see birds in unexpected ways through poetry. Ted Hughes:

Terrifying are the attent sleek thrushes on the lawn,
More coiled steel than living—a poised
Dark deadly eye, those delicate legs
Triggered to stirrings beyond sense—with a start, a bounce, a stab
Overtake the instant and drag out some writhing thing.
No indolent procrastinations and no yawning states,
No sighs or head-scratchings. Nothing but bounce and stab
And a ravening second.

Or you can simply look at them, sit outside for a moment and watch the pigeons puff and coo as they wander head-bobbing over the paving-­stones, pursuing their own pullastrine politics, or the sparrows as they hop from one frozen instant to another, all poise and hungry ­intelligence, or the goslings cozying up together and chirruping in the spring.

None of this is possible with the non-avian dinosaurs. There’s no long mythic tradition concerning dinosaurs, just a few puzzling pots and secondhand stories about Orestes’s tomb. We can encounter dinosaurs through pop culture, but that’s secondhand, too; all we really have is what science can give us. And though the scientific account of the dinosaurs is fascinating, it will always be incomplete. Bones aren’t enough. When the last elephant is dead and forgotten, no future society will be able to conjure its gentle stoic curiosity from that huge fanged cyclops-skull. When we wipe out the last whales, their joyful leaps out of the water will go with them. My parents keep chickens, and sometimes when I visit, and the hens are chuckling to each other in the garden or begging for bits of my apple with a croak and a tilted beak, I wonder which bits of their happy silly lives are echoes of what a dinosaur’s might have been. I can’t know. There’s so much that we will simply never know about the dinosaurs, because they are gone into the great night of the world.

In the triumphalist account, science is the tool with which we will one day know everything. It’s only a matter of time before we explain the Higgs boson, discover the physical processes that produce subjective consciousness, find the universe’s missing ­antimatter, explain why the entire thing is here to begin with, and learn what happened before it began. And maybe we will somehow solve all these questions—but it’s not inevitable. One of the things we know is that not everything can be known. And before Heisenberg’s uncertainty and Gödel’s incompleteness and last year’s mind-­bending revelation that the universe is “not locally real” (look it up), there were dinosaurs: the point at which the world starts actively to resist our attempts to ­understand it.

Young children are fascinated by dinosaurs. I was. I organized a few of the kids who could bear to be my friend into a Dinosaur Club. (Our symbol was the club on the end of an Ankylosaurus tail.) I filled my exercise books with endless pictures of dinosaurs. When I got a new book, I’d always check the index first, to see whether there was anything about dinosaurs in there. Now some of my friends are having their own children, and those children are obsessed with dinosaurs, too. I think I know why. For a child, the adult world is a big confusing place, with all its rules that don’t make sense and its obscene powers that can tell you what to eat or when to go to bed. But dinosaurs tell us that this world is not really so big, or so powerful, and it’s not really so important, either. Once, there were enormous reptiles, and they lived here, on the same earth we’ve covered with suburbs and shopping centers. Our lives are built over the bones of something so much vaster and more potent. And though the grownups can put the remnants of that vastness under an electron microscope, or build simulations on a computer, they will never really know. We will always be a gaggle of small hairless apes, newborn into a very old world, and goggling in wonder at a bone.

Sam Kriss writes from London.

Image by James St. John via Creative Commons. Image cropped. 

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