Читать книгу Lens to the Natural World - Kenneth H. Olson - Страница 12
Оглавление4 / If These Bones Could Speak
The hand of the Lord was upon me, and he brought be out by the Spirit of the Lord and set me down in the midst of the valley; it was full of bones . . . and lo, they were very dry . . . So I prophesied as I was commanded, . . . there was a noise, and behold, a rattling; and the bones came together, bone to its bone . . . and breath came into them, and they lived, and stood upon their feet, an exceedingly great host.
Ezekiel
We could not know the extent of it at first, but the valley was indeed full of bones. More than twenty years ago, my fifth grade son, Garrett, and I were hunting dinosaurs on the prairies of the Great Plains, something we did for two weeks every summer vacation. Always in July, our trips coincided with the hottest weather when temperatures usually climbed to more than 100 degrees in the shade. (That’s something of a euphemism; there was never any shade.) We usually slept in tents, and the sudden, violent, mid-night thunderstorms generated by the heat often sent us running to the pickup cab, our path lit by near-constant lightning flashes, certain that without such refuge we would be blown away. It is all part of what one does to find fossils; however, it is pretty mild when compared to the challenges that confronted the earliest dinosaur seekers, those who explored the badlands with horses and wagons and were often days from the nearest settlements.
We camped not far from a two hundred-foot cliff overlooking a small river that had cut its winding, convoluted way down through the banded sedimentary rocks from the period of time that holds the last of the dinosaurs. The river now occupies a narrow bed that is sometimes reduced to a trickle, but it was not always such a diminutive stream, for it lies within a much larger, much more ancient channel, one of the countless channels for melt-waters from the last continental glacier. Twelve thousand years ago and some distance to the north, the front of the retreating ice would have been nearly a mile thick and waters a mile wide would have swirled and churned in the broad valley just beneath us.
Now, a herd of black cattle grazes down there in the distance; somewhat apart are several bison that a rancher has added to his operation, a practice that is becoming increasingly common in the West. A few cottonwoods dot the flood plain; most of them huge and dying, since new trees are dependant for propagation upon high water, which no longer comes due to the flow being retained and controlled by irrigation dams. A golden eagle rides the thermals above, making lazy spirals in the blue sky. Coyotes howl at first and last light; otherwise, the loudest sound is that of a bumblebee moving between coneflowers, intent upon its business, oblivious to ours.
Ours has to do with still another riverbed, over five thousand times more ancient, the cross-section of which has been exposed by erosion about a third of the way down the cliff. We had found miscellaneous fragments of bone at the bottom. When that happens, one follows the pieces upward, hoping to find the source. Perched on the side of the sixty-degree slope, hacking footholds and probing with picks and knives, the horizon that had been producing the eroded bone was revealed, and it exceeded anything we could have imagined. Wherever we probed at this zone of twelve inches in thickness, there was rust-colored bone—leg bones, ribs, foot bones, ossified tendon, vertebrae, and pieces of skull! The skeletal elements were log-jammed together at a density of about thirty bones per square meter. None of the bones were in place, hooked together as a skeleton; instead, they had been moved in high water and packed together in random fashion, i.e., they were disarticulated. I was interviewed by a newspaper concerning the site, and, when the article was published, it stated that the bones were inarticulate, which would mean they couldn’t speak. However, in their own way, they spoke volumes.
Thus, in addition to working ten hours a day at the excavation, the beginning or the end of a typical day often found one simply in contemplation of the mysterious world of the dinosaurs, more of which was beginning to be revealed with each shovelful of dirt. Regarding such moments, the world-famous paleontologist Robert Bakker writes in his 1986 book, The Dinosaur Heresies, “Reverie is normal in Wyoming at sunrise. I suppose a no-nonsense laboratory scientist, clad in his white lab coat and steely-eyed objectivity, might think I was wasting my time communing with the spirit of the fossil beast. But scientists need long walks and quiet times at the quarry to let the whole pattern of fossil history sink into our consciousness.”
We would return year after year to this same spot, each time cutting in several feet to excavate a platform where we could work to expose and map the extent of the dinosaur material. Then came the process of removing the smaller bones, digging around the larger ones and applying plaster jackets so they could be safely removed, hauling them by rope and stretcher up the steep incline. The huge extent of the bone-bed on the cliff face was now apparent: it was more than four hundred yards wide. After several summers of such exploration by just the two of us, a crew of college students and adults was assembled to work for two or three weeks each summer. A small front-end loader was employed to remove some of the overburden in a process that resembled terracing a road on the side of a mountain. Over the course of a dozen years, more than 6,000 dinosaur bones were removed from the site, and it is likely that acres more still remain in that side-hill.
All the bones are from a single species of dinosaur, the large hadrosaur, or so-called “duckbilled” plant-eater named Edmontosaurus. In addition, we found a number of shed tyrannosaur teeth, suggesting the scene had been a windfall for the carnivores. Bones of other species are absent, indicating that this does not represent a gradual accumulation at the site over time but is the result of a single event. Collections like this, composed of individuals of different sizes, from quite small to nearly forty feet long, provide evidence that such creatures must have traveled in large herds, perhaps in migration. In the Far North, entire herds of caribou may drown in the attempt to cross a wide river in flood stage, and it may be that something similar happened here with a mass kill of dinosaurs. After the carcasses began to decompose, another high-water event must have separated and jumbled the skeletal elements and moved them downstream, there to become packed together and covered by sediment. Locked in the darkness, they remained until another river would begin to expose them to the light of day nearly 70 million earth orbits later and in an utterly different world.
Part of the message of the bones is delivered where they are found, in place. It is a truism in paleontology that as much as half the important data from a specimen can be obtained from its context in the field, paying attention to the conditions under which it was deposited in its original environment. The specimen is then fully excavated and moved to a museum or university lab, where it is cleaned, hardened, missing parts restored, i.e., “prepped” or prepared for study or display.
“Dem bones, dem bones, dem dry bones.” So goes the old spiritual that talks about “the hip bone connected to the leg bone, the leg bone connected to the knee bone,” and on and on. The song’s inspiration is, of course, that prophetic passage from Ezekiel chapter 37. The passage has inspired more than song.
Edwin H. Colbert was one of the leading paleontologists of the previous generation; for more than three decades, he was curator of dinosaurs at the American Museum of Natural History in New York City. He once spoke to his research staff with a huge sauropod or “brontosaur” pelvic bone in front of him, saying: “Bones are truly fascinating things, marvels of structure and form . . . Everything about a bone has meaning: it is a structure shaped for strength or for a particular function . . . it is an integral element of a dynamic, mobile creature, the complexity of which makes our vaunted mechanical vehicles seem simple and crudely limited.”
One thinks here of the words of Walt Whitman, “The narrowest hinge of my hand puts to scorn all machinery.” Colbert continued:
The astute paleontologist sees in his fossils more than petrified bones . . . In his mind’s eye he can clothe the bones with muscles and other soft parts of living animals, and he can cover the ancient animals with skin or scales or hair and picture them as they once appeared in their native environment . . . One might think that he is akin to Ezekiel, who said: “So I prophesied . . . and the bones came together, bone to its bone. And I beheld, and lo, there were sinews upon them, and flesh came up and skin covered them above . . . and breath came into them, and they lived.” These are the undisputed remains of animals that lived great ages ago, and it is about them that we must speak. May our words never be dry.
Not every dinosaur specimen arrives at a museum or research facility, in fact, far from it. Today, fewer and fewer do, because of the dramatic increase in commercial collecting over the past two decades. Private collectors, as well as companies established for this purpose, sell specimens. A few go to museums that buy fossils (most museums do not), but many of them go to private individuals, and many go overseas without scientists ever seeing them. The situation was exacerbated when, in 1997, the largest and most complete Tyrannosaurus rex, nicknamed “Sue,” was auctioned off for more than 8 million dollars. A number of T. rex specimens have been found since, but the incident surely contributed to the commercialization of fossils, especially dinosaurs, and the granting of permission to search for scientific purposes on private land has sharply declined since. I have been extremely fortunate to work with several landowners who have a fine concern for science in general and for the educational value of such objects.
It is a complex situation. On the one hand, some fossils are common, including many invertebrates. Entire mountain ranges are made of limestone, which means they are literally composed of uncountable trillions of organisms that flourished in ancient seas. Some vertebrate animals have left abundant fossils, also. Sharks, for instance, shed and replace their teeth continually; a single one may shed thousands in a lifetime. The same was true in prehistory, making for huge numbers of fossil shark teeth.
On the other hand, some types, such as many dinosaur fossils, are rare; indeed, some are one of a kind. These represent priceless clues to the history of life on earth and should belong to posterity, instead of becoming mere commodities that go to the highest bidder. It is sometimes to “make ends meet” that such items are sold, but not always. Some of the poorest people I know are farmers and ranchers but so are some of the richest. Where one stands on this issue seems to have little to do with wealth or the lack thereof. In response to the question, “How much is enough?” many will always answer, “Just a little more.” Some will say, “A person has to live, doesn’t he?” Yes, but the oft-unasked question is “What for?”
Thoreau wrote about a neighbor who lived on Flint’s pond, “who regarded even the wild ducks that settled in it as trespassers,” an individual who “would have drained it and sold it for the mud at its bottom.” It was “his farm where everything had its price, who would carry the landscape, who would carry his God, to market, if he could get anything for him . . . on whose farm nothing grows free, whose fields bear no crops, whose meadows no flowers, whose trees no fruits, but dollars.”
To illustrate the rarity and the scientific value of some specimens, consider the horned dinosaur Torosaurus. The first descriptions of the creature accented the fact that huge bony frill or shield extending from the back of the skull over the neck is much larger than that of its more common cousin, Triceratops, of which perhaps two hundred skulls have been found. In addition, the frill of Torosaurus has two large holes in it. The rarity of this beast can be seen by the fact that only three skulls had been found in more than one hundred years. The first two were located in 1891 by an expedition to Wyoming from Yale University. Those were approximately 50 percent complete but enough to give it a name. Nothing more showed up until 1944 when an incomplete juvenile skull was found in South Dakota by the Philadelphia Academy of Science. Then, in Montana in 1996, I excavated a huge Torosaurus skull and delivered it to the world-class Museum of the Rockies at Montana State University in Bozeman, which now houses the largest collection of American dinosaur specimens in the world. It is there that I have practiced my serious avocation as a research associate in paleontology. At nine feet long, it was the largest dinosaur skull in the world.
Rare as they are, I thought I would never see another one in the ground. Then, in 1999, I was visiting a rancher and seeking permission to explore his land, something he readily gave. As I was about to leave, he took me into his garage to show me a piece of bone he had picked up twenty-five years earlier. It was apparent to me that it was a fragment of the skull of a ceratopsian or horned dinosaur, so I was anxious to see how much more could be found. The site was located, and over the next few weeks I made seven trips there to begin exposing what would turn out to be specimen number five of Torosaurus, the most complete and best preserved one yet. The next summer, several of us from the Museum of the Rockies were involved in the remainder of the excavation at the base of a twenty-five foot cliff. Jackhammers, picks, and shovels were used to cut a pickup-sized cave in the sandstone wall and the skull was jacketed in two pieces that together weighed an estimated four thousand pounds. Another winter passed, but in the summer of 2001 the Army National Guard was available for a training exercise in which two Black Hawk helicopters would lift what could be moved in no other way. On July 21, at the crack of dawn, when the air is most still, the great skull nine feet long and over six feet wide rose into the air. (One of the pilots said later, “I don’t know why we had to get up at three-thirty in the morning to come and get something that’s been in the ground for 68 million years!”)
The event was filmed by several media outlets and carried “live” by NBC television’s Today Show, and CNN picked it up and sent it around the world. It was an event illustrating both the popularity of dinosaurs and the large number of people and the amount of resources necessary to rightly handle a specimen of this importance.
The world-renowned dinosaur specialist Jack Horner, who oversaw the excavation, was asked, “So, is this the kind of moment paleontologists live for?” “Well, it certainly is,” he replied. “The next great moment will be when we can get it to the Museum where everyone can see it.”
And that’s the point. Such things belong to the ages. The two giant skulls are now central exhibits in a new dinosaur hall, where their bones will speak to the public of the diversity of life through time. Over generations, millions of people will be able to see them and most will surely stand in awe before these, two of the largest skulls of any land animal ever.
Torosaurus has been known by that name for more than a century, but an unexpected perspective was recently provided by a scientific paper published in 2010 by Horner and one of his graduate students, in which they conclude that the few existing skulls of Torosaurus may actually be the final growth stage of very aged individuals of Triceratops. In a situation not uncommon in paleontology, a number of others disagree, illustrating the sort of debates that often take place in science. However, and in line with “a rose by any other name would smell as sweet,” these specimens—whatever their designation—are still of wonderful creatures from the primeval world of the dinosaurs and, as such, will continue to stir the imagination.
The word “museum” comes from the root verb “to muse,” i.e., to think, to reflect, consider, or to wonder. This is a purpose far deeper than mere entertainment, which usually consists of a-musement, i.e., to not think, to neither consider nor wonder. Among the latter is much television programming, wherein the average scene is three and a half seconds. One is reminded of George Bernard Shaw’s visit to New York City when he was being driven down Broadway. About the profusion of neon lights and advertising, he said that it must be beautiful, if you cannot read.
Natural history museums exist to expand our understanding; we cannot wisely guide our course in relationship to the life-systems on which we depend without sound knowledge of how they operate. Practical considerations aside, they also have the purpose of eliciting our admiration for the dynamics of planet earth and the complexity of life. Without that, it is as though we stand in a gallery that has the great works of art all facing the wall. A simple appreciation of our place in nature is essential to our humanity.
There is, however, a subtle danger to which institutions are prone as they attempt to describe the natural world. Many nature and science museums are not as much about nature as they are about technology. Even when the subject is that of various animals, the fact that robotics and synthetic sounds often dominate will lead to the subconscious focus not on the creature but on the human inventor. Nature is divided into bite-sized segments that are isolated from their contexts and hyped by electronics. The displays are often, therefore, less about the world and more about our domination of it. It is a mentality with a long pedigree, as Cicero boasted, “We are absolute masters of what the earth produces. We enjoy the mountains and the plains . . . We sow the seed and plant the trees. We fertilize the earth . . . We stop, direct, and turn the rivers. In short, by our hands we endeavor by our various operations in this world to make it, as it were, another nature.”
Consider the zoo in almost any large urban center, even the most spacious and ecologically minded, and, in the words of Scott Russell Sanders:
You will find nature parceled out into showy fragments, a nature demeaned and dominated by our constructions. Thickets of bamboo and simulated watering holes cannot disguise the elementary fact that a zoo is a prison. The animals are captives, hauled to this space for our edification or entertainment. No matter how ferocious they may look, they are wholly dependent on our care. A bear squatting on its haunches, a tiger lounging with half-lidded eyes, a bald eagle hunched on a limb are like refugees who tell us less about their homeland, their native way of being, than about our power . . . Snared in our inventions, wearing our labels, the plants and animals stand mute. In such places, the loudest voice we hear is our own.
Planetariums simulate not only the naked-eye vision of the sky but sights from deep space that, otherwise, would be closed to all but a few. As such, they more nearly facilitate the muse. Some things, of course, should not need such help. A few decades ago, when, for the first time, a lunar eclipse was shown on television, most people watched it on the silver screen, this when they could have stepped outside and seen the real thing.
A dinosaur bone, however, needs neither magnification nor exaggeration. It is what it is, whether in isolation or in an articulated skeleton: a tangible artifact from a creature that lived in an inconceivably remote period on planet earth.
Museums often use casts made from molds of the bones. These are near-identical reproductions and have several advantages, including that they can be shipped across the world for study or posed in mounts when the actual bone would be too heavy or fragile or when such exhibits would be too costly. But the authentic bone itself has a mystique that is unrivaled. Even the first-graders have learned to ask about a dinosaur specimen, “Is it real?” If not, at least some of the interest departs. If it is real, the eyes grow wide with excitement and wonder. The fact that museums can display such objects of fascination, often close-up, contributes to the popularity of the whole subject of dinosaurs. Some have called dinosaurs “nature’s special effects,” with the added attraction that they were real.
It is quite an understatement to say, concerning the role of dinosaurs in today’s culture, that they are popular. It was in 1842 that England’s Sir Richard Owen coined the name dinosaur to describe a new order of reptiles, this after the Greek words deinos for “terrible” or “frightfully great” and sauros, for “lizard.” Deinos might be equally well translated “awful,” this in the original sense of awe-full, and “Awesome!” is a phrase heard often in dinosaur halls these days.
The fascination with things prehistoric has meant that paleontologists who study dinosaurs no longer work in obscurity but have become celebrities. Blockbuster movies like Steven Spielberg’s Jurassic Park (mostly about Cretaceous instead of Jurassic dinosaurs) fuel the imaginations of millions. Jack Horner was advisor to that film, as well as the sequels, and his persona served as the model for the main character played by Sam Neill. (Perhaps the reader will remember an early scene in Jurassic Park III, in which the paleontologist drives up to the dig site in a Museum of the Rockies pickup.)
In 1996, Arizona State University at Tempe hosted a month-long extravaganza concerning dinosaurs and other prehistoric beasts. The thousands who attended viewed entire skeletons on display, as well as a many other fossils. (Since then, there have been numerous other such Dinofest events at other sites around the country.) Included was a four-day symposium that featured dozens of researchers. The paleontologist Peter Ward describes the atmosphere of the event: “All the big name dinosaur guys were there, and the two biggest of all, Jack Horner and Bob Bakker, could easily be found simply by looking for the biggest crowd. As each passed through a room or hall, a retinue of attendees, groupies, and curious onlookers followed.”
Publicity in this era knew little bounds. Horner appeared on the cover of US News and World Report with the banner, “What Dinosaur Detective Jack Horner Does in the Real Jurassic Park,” i.e., Montana. In the 1990s, numerous magazines put forth cover articles, such as that by Newsweek bearing an image of T. rex: “Could Dinosaurs Return? The Science of Cloning.” Television documentaries on the subject of dinosaurs are continually in production, and newspapers report on dinosaur digs. Entire industries exist to crank out dinosaur toys and, of course, T-shirts are nearly ubiquitous.
Horner’s discoveries of dinosaur eggs (some containing embryos) and babies in nesting sites at the front range of the Rocky Mountains in Montana had made news the world over. They were the first complete such eggs ever found in North America. It was not only a discovery, however. It led to an image of entire nesting colonies of giants. In describing their environment, Horner provided a new picture of huge reptiles caring for their young, and he named the dinosaur involved Miasaura, meaning “Good Mother Lizard.” Baby dinosaurs became hugely interesting to millions. (Among the very best works to show how paleontology actually works are his Digging Dinosaurs: the Search that Unraveled the Mystery of the Baby Dinosaurs and his Dinosaur Lives: Unearthing the Evolutionary Saga. A fascinating new look at the iconic Tyrannosaurus rex is found in Horner’s The Complete T. rex. Written specifically for amateurs to aid in properly treating and identifying dinosaur fossils is his Dinosaurs under the Big Sky.)
In 2010, Horner was interviewed about dinosaurs on CBS television’s 60 Minutes. In addition to authoring numerous articles in scientific journals, he has appeared in a host of documentaries and been the subject of many magazine and newspaper articles. Thus, a case could be made for saying he is one of the most famous or recognizable living scientists of any sort in the world today. Yes, the subject of dinosaurs is fascinating.
Reasons why dinosaurs are so popular are many, and not all may be fully open to analysis. They surely do speak to the mind’s ability to conjure up scenes long past and populate them with creatures we could never see in any other way. Charles H. Sternberg, born in 1850, was one of the greatest of all fossil hunters, collecting prize specimens of dinosaurs, marine reptiles, and prehistoric mammals for several of the world’s premier museums. He wrote, “It is thus that I love creatures of other ages . . . They are never dead to me; my imagination breathes life into ‘the valley of dry bones,’ and not only do the living forms of the animals stand before me, but the countries which they inhabited rise for me through the mists of the ages.”
For children, the fascination may have something to do with the “monster” image of many of them, this combined with the fact that, being extinct, they are now safe to confront. For any and all, the puzzle of extinction also exerts an attraction; how could a group so successful for so long disappear?
For adults, interest in dinosaurs surely has much to do with new information about them that has emerged in the last twenty years. Approximately every six or eight weeks, a new dinosaur species is described and named; there are now more than a thousand. No longer is their image that of the painfully obsolescent, slow, cold-blooded, stupid, green tail-draggers in the swamp that were simply too outmoded to survive. That image is humorously portrayed in The Far Side cartoon by Gary Larson that shows a Stegosaurus standing at the podium during a dinosaur convention. Speaking gravely to his “dino” audience, he says, “The picture’s pretty bleak, gentlemen . . . The world’s climates are changing, the mammals are taking over, and we all have a brain about the size of a walnut!” In fact, dinosaurs dominated the world scene for at least 150 million years, indicating they were masters of survival. Active and dynamic creatures they were, and many of them, particularly the meat-eating “theropods,” are likely to have been warm-blooded.
In 1964, John Ostrom and his crew from Yale University were working in the badlands of Montana when they struck paleontological gold. In the resulting scientific paper, he wrote, “Among the important discoveries made was that of the spectacular little carnivorous dinosaur described here—an animal so unusual in its adaptations that it undoubtedly will be the subject of great interest and debate for many years among students of organic evolution.” It was Deinonychus—the name means “terrible claw”—a creature similar to Velociraptor, those fierce, if rather enlarged, killers portrayed in the kitchen-scene in Jurassic Park. Ostrom was right: the specimen ignited a wide-ranging debate on several aspects of dinosaur relationships, including that of their relationship to birds.
In addition to laying eggs and having three-toed feet, some dinosaurs had hollow bird-like bones. There is evidence that they had air-sacs, which, as in birds, extended from the lungs into much of the rest of the body and into some of the bones of the skeleton. Some even had clavicles (to become wishbones). Fossils of small dinosaurs found in China clearly show feathers, which may have been brightly colored. These are just a few of numerous characteristics shared with birds.
In fact, most paleontologists now regard the system of animal classification developed by Linnaeus, which served well for more than two hundred years, to be in need of revision, and they go so far as to say that recent discoveries strongly support the idea that dinosaurs are birds. If this is true, then we can say that at least some of the dinosaurs are still with us. In biologic nomenclature, Aves is the Class occupied by birds. Not only the scientific literature but now almost every new dinosaur book talks about “avian” dinosaurs (i.e. birds) and “non-avian” (traditional) dinosaurs. As an example, the popular book, Discovering Dinosaurs in the American Museum of Natural History, has a chapter entitled, “Why Did Non-Avian Dinosaurs Become Extinct?” Another chapter includes a photo of the world’s smallest bird perched on a penny (and about the same size). Below is this caption: “The smallest dinosaur is the bee hummingbird, Mellisuga helenae, found only on Cuba.”
Robert Bakker, as long ago as 1975, published a lengthy Scientific American article titled “Dinosaur Renaissance,” in which he detailed several aspects of the anatomy of a number of prehistoric creatures and concluded with the statement, “The dinosaurs are not extinct. The colorful and successful diversity of the living birds is a continuing expression of basic dinosaur biology.”
Therefore, when V-shaped flocks of Canadian geese are seen coursing through the skies in the month of March, some of us are prone to think, “The dinosaurs are migrating. Spring cannot be far behind.”
The bird-dinosaur connection became vivid for me over the course of a recent springtime that found me making an 800-foot ascent in the foothills of a nearby mountain range. It is a climb upward through time. There, each step may span thousands of years of strata, in this case of marine shale and limestone that was laid down in the Jurassic Period some 150 million years ago. Oyster shells are exposed in the rocks and have weathered out in profusion. This was also the time, elsewhere, of Archaeopterix, the primitive bird with a bony tail, teeth set in sockets in its jaws, and claws on its wings. Now, millions of years after those ancient oceans left behind their telltale fossils, my path leads near a large ponderosa pine tree where a pair of golden eagles has built a huge nest. My heart is beating faster from carrying the needed equipment up the steep slope but also in anticipation of seeing the wild creature that, to me, holds a fascination above all others.
I enter the small portable blind, which had been staked down almost two months before and camouflaged with pine branches in order not to disturb the birds. In a few minutes, my equipment is in place: tripod, camera, and an extreme telephoto lens that magnifies approximately twenty-four times and enables detailed images of what would otherwise be indiscernible. Soon, an eagle chick, in a white, downy covering perches on the edge of the nest. The chick has a large head and stubby wings and looks like—a dinosaur. (Many researchers now imagine the young of even the large meat-eating dinosaurs, such as T. rex, to have had downy feathers for insulation.)
Several weeks later, the bird has grown to be nearly as large as an adult eagle. The parents have fed it well. (On one occasion, I photograph it feeding upon half the carcass of a whitetail deer fawn that had been carried into the tree.) A small airplane passes overhead, and the young eagle’s eyes follow it with intense interest, as if thinking, “You can do that?”
Now, with a full set of feathers, the dark brown raptor often faces the wind and flaps its wings, even rising a bit from that platform of sticks in the sky. Then comes the day when it works its way out onto the far end of the branches that support the nest. There, it flaps a bit more, then stands motionless, gazing far outward and beyond. Not quite ready yet to catapult into empty space, an awkward turn-around is executed, and it moves back to the safety of the only world it has ever known. That scene, repeated several times, was reminiscent of a youngster edging out on the diving board at the local swimming pool: hesitating, wondering whether to take that first plunge, wanting it, yet fearing it. The next day, when I came back, the young eagle was nowhere to be seen. The thin air would now be its home for much of its life. The dinosaur had flown. Paleontologists say birds are dinosaurs, and I believe it.
Among the pieces of information contributing to a renewed interest in the prehistoric world are some that we never thought could be obtained, such as the presence of a so-called “medullary” bone layer found in a Tyrannosaurus rex femur that confirms the beast’s gender. Such bone, rich in calcium, is deposited in the skeletons of female birds (more connection) during the egg-laying cycle. So, it seems this rex, (first named “Bob” after Bob Harmon of the Museum of the Rockies, who found it) is really a female. The discovery was described by Mary Schweitzer, Horner, and others, in the journal Science in 2005. In that same year, they detailed still another remarkable find having to do with the same specimen. Following an acid-bath process to dissolve away hard, fossilized bone, some soft tissue remained behind: elastic, vessel-like material with cell-like structures within. This was a first-of-its-kind revelation, and the preservation astonished dinosaur researchers around the world. More work was done on the specimen in 2007, using mass spectrometry to find proteins, and they were found to be most closely linked to—you guessed it—birds. New techniques are leading to new discoveries.
Some phenomena are less subtle and the bones speak quite graphically, which is the case with a unique Triceratops dinosaur pelvis I excavated some years ago. It shows fifty-eight bite-marks made by the teeth of Tyrannosaurus rex. The specimen consists of one of the hip-bones plus the ten fused vertebrae in between the hips called the sacrum. The left hip-bone has had some 15 percent of it bitten off, and the other one is gone completely. Bite-marks of every size and description abound. In a sense, it is fossilized feeding activity of Tyrannosaurus. Based on this fossil, paleontologist Greg Erickson and I described such behavior in The Journal of Vertebrate Paleontology in 1996. The specimen has also been featured in a number of television documentaries, books, and magazines, and Erickson referred to it in a cover article in Scientific American that sought to depict the lifestyle of this largest of dinosaurian carnivores.
One bite-mark shows that a tooth entered at an angle, dragged backwards, making a long groove, then splintered off bone. Numerous other marks are of various depths. A Tyrannosaurus tooth can fit in many of the holes, leaving no doubt about the source. Sometimes, such teeth are compared to steak knives, but that is misleading; the teeth are not narrow, for slicing. Instead, they are round/oval in cross-section, and shaped something like bananas (and the same size!). They are robust and strong, designed for puncturing and tearing off huge hunks of meat and for breaking bone. Erickson further studied the specimen by having a hydraulic press constructed with metal “teeth” and, with it, duplicated such marks in modern bone. It seems that T. rex had a bite-force of at least 3,300 pounds, which is the largest of any known animal and is the equivalent of having the weight of a good-sized passenger car bearing down upon the teeth.
The information that can be gleaned about the behavior and physiology of an extinct creature, even across tens of millions of years, is quite amazing. The bones of the fearfully great reptiles can now speak in ways never previously imagined, something that is at least part of the explanation for why dinosaurs are striding so large across our culture today.
