"Sixty-five million years ago, a world that belonged to the dinosaurs suffered a cosmic catastrophe, obliterating the kingdom of Tyrannosaurus rex." "For sixty-five million years, the bones of the last king of the dinosaurs lay hidden." "Then at the turn of the 20th Century, scientists began to coax the first fragments from the Badlands of western North America." "It stood eighteen feet tall." "Forty feet from head to tail." "Today, the bones of Tyrannosaurus rex allow us to encounter the greatest meat-eating machine of the prehistoric world." "Tyrannosaurus rex has become the most famous of the dinosaurs, the ultimate expression of savagery and power." "For paleontologists like Phil Currie, who scour the bone yards of the North American Badlands in search of the real T. Rex, a close encounter is a rare and thrilling event." ""The thing that allows Tyrannosaurus to be preserved in this part of the world is the fact that they were living on a coastal lowland, and there was a tremendous amount of sediment coming in from the mountains that were rising to the west at that time." "So there were large rivers running across the coastal lowland." "And if the Tyrannosaurus, ah, body happened to fall in the water, then it had a very good chance of being buried complete." "And, ah, fast burial is one of the most critical factors in terms of, ah, preserving an animal that large."" ""So far, seventeen skeletons of Tyrannosaurus have been found, all of them from Wyoming north into Alberta and Saskatchewan." "Now, Tyrannosaurus probably had a much more extensive range than that." "It almost certainly lived all the way from, ah, the Arctic Ocean down to the Gulf of Mexico."" "Only seventeen skeletons have been unearthed of the many millions of animals that once lived and died, a handful of clues to the mysteries of this ferocious, but elusive, beast." "The existence of the king of the dinosaurs was unknown until 1902, when a former Kansas farm boy named Barnum Brown, hunting dinosaurs for the American Museum of Natural History, discovered its remains." "A dinosaur bone used as an offiice paperweight had caught his attention." "Brown traced it back to Hell Creek in Montana." "But what would he find there?" "Even the man who would become known as Mister Bones could hardly dare to hope for the rarest of the rare, a giant meat-eater." "But that is exactly what he found, halfway up a steep and treacherous canyon wall." "But six years of backbreaking work yielded only incomplete fragments." "Then in 1908, Brown discovered the almost intact skeleton he would call "my favorite child"." "For Tyrannosaurus rex, the journey back to life and legend had begun." "Back at the Museum in New York," "Brown's boss, Henry Fairfield Osborn, was eager to show the world the animal he named Tyrannosaurus rex." "While the bones were being prepared," "Osborn and Brown used models to recreate a dynamic vision of the living tyrant lizard king." ""Long, powerful hind legs carried the body upright, balanced by a long tail." "The massive head was armed with thirteen dagger-like, saw-bladed teeth in each jaw." "The Tyrannosaurus was capable of destroying any of the contemporary creatures, and was easily the king of the period and monarch of its race."" "But nearly two tons of bones could not be mounted to match Osborn and Brown's vision of an agile, almost bird-like beast." "Their compromise design for an upright, more static pose, which we now believe to be wrong, dominated how we saw T. Rex for more than fifty years." "The unveiling of T. Rex in 1915 created a popular sensation." "The ages roll on and reptiles grow to monstrous size." "The "tyrant giant Lizard" (Tyrannosaurus)" "The upright T. Rex became the horror movie superstar of a new Age of Dinosaurs." "Through generations of life in the forests and bitter struggles among themselves, these powerful beasts develop hides like armor." "Eighty years later in Montana, the painstaking search begun by Barnum Brown for the real" "T. Rex continues." "Bill Garstka and his team are unearthing the first fragments of what he believes is a new and important skeleton." ""This was the first piece of bone that I picked up at the site." "This is distal end of fibula, the small bone of the leg." "So it sits something like this into the ankle of the animal, and it is interesting in several respects." "First of all, you see this iron core in the middle?" "Carnivorous dinosaur bones are hollow." "This was the first indication that I had something really interesting."" ""We had not been here oh, even ten minutes picking up fragments when Shawn, who is the group leader, found this." "And this is a Tyrannosaurus tooth." "And this has the enamel weathered off." "But it still has the ridges where the serrations on the enamel would have been." "So we knew with these two pieces that we had a Tyrannosaur."" "Even with modern power tools, dinosaur hunting in hundred degree temperatures is backbreaking work, yet so delicate that removing an entire skeleton can take years." "Today, just as they did one hundred years ago, the bones of T. Rex leave the Badlands as precious cargo, protected in plasterjackets." ""Okay."" ""All right." "Oh, good."" ""Ah!" "I got it."" "But fossilized bones are not the only remains that can shed light on the life of an animal." "There are many other clues that can fill in some crucial details." ""My concern is the world of T. Rex." "What plants did it live with?" "What sort of foliage hit it while it stalked its prey?" "What had happened was the flowering plants appeared early in the Cretaceous period." "And by the time of Tyrannosaurus rex, they were dominating the world's ecosystems." "We find in North Dakota that ninety percent of our fossil leaves, and we now have over thirty thousand fossil leaves collected, over ninety percent of those fossil leaves are broad-leafed flowering plant leaves." "What you see are, here broad-leaf relatives of the laurel and cinnamon." "Relatives, two-lobed relatives of magnolia." "Relatives of the modern sycamore." "Relatives of the modern elm."" ""There are still a few conifers around in the time of Tyrannosaurus rex, the bald cypress and its relatives." "So the look of the place was similar to say, perhaps, Florida or southern Georgia, where you have relatively small trees, maybe thirty or forty, fifty feet tall, trunks no more than maybe a foot in diameter."" ""By the time Tyrannosaurus was living in North America, most of the modern families of plants and animals had already appeared on the earth." "Consequently, the world that Tyrannosaurus lived in may not have been as foreign as we think it is." "In fact, we can almost go to parts of the world today and see representatives of those animals and plants still alive today." "And you would have crocodiles and turtles and, ah, lizards and snakes and all these things." "Ah, they would have been very familiar to us today." "The difference would have been that the large animals which today are large mammals, at that time would have been dinosaurs."" "Just as plant-eating animals outnumber meat-eaters today, the plant-eating dinosaurs outnumbered carnivores millions of years ago." "Phil Currie is leading a team of scientists excavating a herd of duckbilled plant-eaters called edmontosaurs." "Dinosaurs like these probably were favorite dinners for T. Rex." ""Well, we got about, ah, I would say sixty-five or so Tyrannosaur teeth, a few small theropods, lots of tooth-marked bone as well."" ""Do you think there is enough edmontosaurus material in here to, ah, indicate that this was a herd of edmontosaurus?"" ""Well, we have got at least, um, eight individuals, ee... big edmontosaurs." "And we also have evidence of some very small animals based on some of the lower limb bones." "So it appears that we have got older adults with smaller individuals which, to me, indicates we may have had a herd in this area."" ""Bone beds like this, ah, are pretty good indication that many of the prey species for animals like Tyrannosaurus rex were, in fact, herding animals." "These, ah, animals, ah, were herding probably because they were moving from region to region, ah, as food resources changed over the course of the year." "Ah, I would suspect that the Tyrannosaurs were, in fact, following these herds, and that the old individuals and that the young individuals that strayed too far from the herds were the most likely prey for the Tyrannosaurs." "And these are the animals they actively hunted down."" "The discoveries of the past century have made Tyrannosaurus rex one of the most famous and the most fearsome of nature's creations." "But how did such a ferocious giant come into being?" "Where does it fit in the history of life on earth?" "Today, we know that T. Rex's ancestry can be traced back to a tiny creature, whose skull can fit into the palm of your hand." ""This is eoraptor, or the dawn stealer." "It is the oldest and first predatory dinosaur that we know of in the fossil record." "And it has some of the, ah, basic adaptations that were to carry predatory dinosaurs, ah, through a hundred and fifty million years of evolution to something like the Tyrannosaurus behind me." "The skull shows some of the classic features of the predatory dinosaurs." "Ah, one of those features involves the lowerjaw." "At a, the mid-point of the lowerjaw, there is a joint that allowed the lowerjaw to flex, ah, like a flexible joint that if something was caught in the jaws, those jaws would clamp around, ah, something that might be a live prey item." "And this kind of a lowerjaw is present in Tyrannosaurus." "It is present in every other predatory dinosaur that we know of." "And eoraptor is the first to show that adaptation in the fossil record."" "The body plan, road-tested in eoraptor, became an evolutionary best-seller." "Even today's birds, themselves thought to be modified dinosaurs, owe much of their design to these long-tailed ancestors." "But how did T. Rex evolve from the size of a small dog into a forty-foot giant?" "For decades, many scientists thought it had to be descended from other giant predators, like this allosaurus, the last in the line of ever-larger, ever-toothier dinosaurs." "This was the super-carnosaur hypothesis." "It may have seemed obvious, but it was wrong." ""We used to have very simple views about how the different groups of meat-eating dinosaurs were related to each other." "In recent years, though, as we have discovered more and more about the anatomy, these views have changed." "Tyrannosaurus at one time was considered to be a carnosaur, that is, one of the large, meat-eating forms." "And by its size, it was related to animals like allosaurus." "But in recent years as we started to look more closely at the anatomy, there were a lot of things about Tyrannosaurs that did not fit that picture."" ""One example is the foot." "And if we look at this, ah, pinched-out third toe, in fact, this is the kind of characteristic we see in many of the other late Cretaceous dinosaurs." "But all of them are small dinosaurs." "They are not these big meat-eaters that we are so familiar with, animals like allosaurus." "Looking at the foot and a whole suite of other characters in the skeleton, we now realize that Tyrannosaurs are, in fact, small meat-eating dinosaurs that have grown extremely large, and they are not related to the other" "meat-eating dinosaurs that are large at all."" "Anatomical detective work can easily identify dinosaurs to whom" "T. Rex is not related." "But tracing its family tree back through time is more diffiicult." "A huge gap in the fossil record precedes the sudden appearance of T. Rex's first large predecessor." "But recently, some of the missing clues have been found four thousand feet up in the mountains of Alberta, Canada, on a prehistoric beach frozen in time, thrust on its side over millions of years." ""The richest dinosaur footprint site in all of Canada is in a coal mine in Grand Cache, Alberta." "In these hundred million year-old rocks, we have evidence of, ah, armored dinosaurs, ah, meat-eating dinosaurs of different kinds, and large plant-eating dinosaurs."" ""The footprints are all in trackways, and they go across this, ah, enormous cliff face which, at one time, must have been a mud flat at the edge of the sea."" ""What is important about this site is that because of the age, a hundred million years ago, ah, we do not have equivalent bone sites in this part of the world." "And so, we have to do a little bit of guesswork in terms of identifying the dinosaurs." "And I do not think there is any question at all that these are not Tyrannosaur tracks." "But their long, slender toes suggest to me that these were made by giant coelurosaurs." "And we feel these days that giant coelurosaurs may have been the ancestor of Tyrannosaurus rex."" "The coelurosaur was a turning point in the evolution of Tyrannosaurus rex." "Unlike other small predators of its time, it used its jaws rather than its front limbs for killing its victims." "That adaptation would set the stage for the rise of T. Rex and its unique appearance." "The earliest of the Tyrannosaur family is called alectrosaurus." "It is a long, slender animal with relatively long front limbs." "By the time albertosaurus evolved, its head was larger and its front limbs shorter." ""There were certainly many species of Tyrannosaurs." "We, at present, know of more than half a dozen species." "The earliest fossil record of albertosaurus is about eighty million years old." "This animal in its external features really is not all that different from Tyrannosaurus rex." "But when you start looking at specific characteristics, there are features which suggest it is more primitive than" "Tyrannosaurus rex itself."" "But who was T. Rex's closest relative?" "Opinion is divided between two candidates, one from North America known as daspletosaurus and another from Asia known as tarbosaurus." ""Tarbosaurus is an animal that originally was called Tyrannosaurus as well." "It, ah, has a number of differences." "But when you start looking at other specifics, ah, for example, the orientation of the back of the skull in relation to the neck, tarbosaurus shows a lot of characters that, ah, suggest to me, at least," "that it may be more closely related to Tyrannosaurus rex."" "But a recent find from Montana convinces Jack Horner of T. Rex's American ancestry." ""Daspletosaurus is the animal that, that I believe and, and, and some others also believe, was actually the predecessor of Tyrannosaurus rex, in other words, its ancestor." "Tyrannosaurus rex was the descendant of daspletosaurus." "Tyrannosaurs, they have a big horn over top of their eye." "And we see, we see it very dominant in Tyrannosaurus rex." "We see it less dominant in this particular animal that is related to daspletosaurus and even less so in the more primitive daspletosaurus."" "The ancestry puzzle may take a long time to solve." "But one trend is clear." "As the Tyrannosaur family evolved, they not only grew larger, they changed to cope with their increased size." ""There are a lot of changes that are necessary if you are going to become a large animal." "And, ah, this is particularly true when we are talking animals like the meat-eating dinosaurs, because essentially they were teeter-totters." "They were animals where the front of the body was balanced by the tail on a fulcrum which was at the hips."" ""Now in Tyrannosaurus' case, as it got bigger, the head became disproportionately larger, and that is to house all those very large vicious-looking teeth." "Consequently, we see a lot of specializations in Tyrannosaurus that are meant to bring the body weight down in front of the hips." "The skull is, ah, a long, heavy skull." "But many of the bones, in fact, are air-filled." "The neck has been recurved, much more so that in earlier meat-eating dinosaurs, simply because by doing that it could bring the head back closer to the hips and shift the center of gravity further back as well."" ""Finally, and probably most conspicuously, if you look at the front limbs of Tyrannosaurus, they have become also extremely short." "They were relying on their head to do the killing." "The limbs could be shortened up and would give it a great savings in weight on the front end of the body." "And it was one more of the adaptations that Tyrannosaurs picked up."" "Ever since the first skeleton of T. Rex was assembled eighty years ago, most people have assumed that the king of dinosaurs must have been a slow and lumbering beast." "But that view is changing." ""From this position, one gets a sense of what an enormous animal Tyrannosaurus rex really is." "In fact, this animal is so big and so massive, that for a long time everybody thought that this had to be a slow-moving animal." "In recent years, though, we have been looking more closely at the anatomy of the hind leg of these dinosaurs and what we see is not necessarily what we expected to see."" "The relative proportions of the individual leg bones of Tyrannosaurus give us an idea of how fast this animal could be." "Now, in fast-moving animals like ostriches, the upper leg bone is relatively short compared to the lower leg bones." "In Tyrannosaurus, we see the same kind of pattern." "Lower bones are as long or longer than the upper bones." ""This, ah, continues, in fact, down into the foot where, if we look at the flat of the foot, or what would be the flat of the foot in a human being, this unit is also very long." "All in all, then, if we look at the characters that we see in the hind legs of Tyrannosaurs," "I do not think there is any question at all that in spite of its massive size, this is an animal that was built for speed." "And it is an animal that it, in fact, could outrun any of its potential prey in its world."" "But Jack Horner has studied the same evidence and drawn the opposite conclusion." "He is convinced that T. Rex was a walker, not a runner." ""If we look at the leg bones of a meat-eating dinosaur, ah, named troodon, what we see is a thigh bone and a shin bone that have different lengths." "We see that the thigh bone is shorter than the shin bone, and this is true of every single one of the non-Tyrannosaurs." "We see the same thing in ostriches." "We see the same thing in emus and rheas and, and all these running birds."" ""Animals that run fast have a short thigh bone and a long shin bone." "The primitive feature is running." "That means, in evolution, you have to evolve legs for walking, because there were no dinosaurs that were adapted for walking before we get to the Tyrannosaurs." "If we look at Tyrannosaurs, the thigh bone and the shin bone are either the same length or the thigh bone is a, is slightly longer than the shin bone." "This is a feature that is good for walking."" "But the high plains of New Mexico may offer more direct evidence of exactly how fast T. Rex really moved." "Martin Lockley follows the trail of fossilized footprints across North America." "He has seen and cataloged thousands." "But one footprint receives special treatment." "It is so unique that its location is a tightly-guarded secret." ""We are inside a high security area in the New Mexico back country." "This fenced enclosure contains this extraordinary and unique fossil footprint." "This the only Tyrannosaurus footprint anywhere in the world."" ""This footprint was probably made not far from some river in the mud, and then it was filled in when the river flooded and washed a sheet of sand over this trampled area."" ""This is the casting that was filled in by sand, now sandstone." "This track is on the order of, um, three feet long." "And it is, ah, two feet wide, and it is almost a, a foot deep." "This was made by an animal that probably weighed in at around, ah, five tons." "It is sitting on a block that is about nine feet long." "There is not a second footprint in that space, so that this means a minimum step of about nine feet." "And if we calculate or estimate the speed of this animal, it was probably moving along at, at least, ah, eleven kilometers, something like six or seven miles per hour, which, which is a, is pretty good, ah, clip." "It would be a jog for a, a human being."" "The movements of modern birds can also shed light on how dinosaurs traveled." "Jim Farlow studies Australian emus and their similarities to T. Rex." ""It would be nice to know what Tyrannosaurus was like as a living animal, but it is very inconveniently extinct." "And if you want to get a picture of how it moved, what it might have been like when it was alive, it is helpful to look at modern animals that give us an approximation to something like Tyrannosaurus." "And of such modern animals, I think the emu is about as good a model as one could hope to find." "I suspect it is probably faster than Tyrannosaurus was."" ""Ah, an emu in the wild can go what, ah, fifty, maybe sixty kilometers an hour?" "Tyrannosaurus, obviously we have no direct way of, of determining how fast it could go." "But based on the calculations of the strength of its bones relative to the size of the animal," "I would think that a, at a good ball-park figure for the top speed of Tyrannosaurus might be something on the order of thirty, forty kilometers per hour."" ""If you look at the way this emu walks, the way it puts its feet one in front of the other, it is a striding walker." "It does not hop like a kangaroo." "And if you look at the way it picks up its feet as it goes," "I think this is about as close to a" "Tyrannosaurus as we can find in our modern world." "And that is part of the fascination that emus have for me."" "But emus and other modern birds without tails may not provide a completely accurate model." "Other scientists pursue a more distant cousin." ""The animal I have here and the reason I think crocodilians are worth spending a lot of time looking at, ah, this is a salt-water crocodile and it retains many of the features that we think the primitive" "dinosaur ancestor might have had." "We know that birds and crocodilians are dinosaurs' closest living relatives and so they are the logical place to look for information on how" "T. Rex works."" "The muscle that I have spent a lot of time looking at, ah, originates from the side of the tail." "As you can see, crocodilians have a long, heavy, muscular tail." "And along here where my fingers are is a large muscle that runs forward to attach onto the thigh bone, the femur." "What we see in modern birds is that the tail itself has been reduced dramatically." "Most of what we see in a bird tail is actually just feathers rather than muscle and bone." "X-ray films prove that the presence or absence of a tail is a vital factor in the movement of an animal, be it bird, crocodilian or dinosaur." ""What we are seeing in the X-ray films is that crocodilians and birds have very distinctive ways of moving their legs." "The question was, which of those patterns can we apply back to a dinosaur like Tyrannosaurus?" "Birds use a lot of knee movement." "The hip is very, very stable." "Ah, whereas in crocodilians, they are using lots of hip movement, and that seems to be driven by this muscle running from the tail to the thigh bone."" ""Fortunately for this muscle, there is a very distinct scar, a bony attachment on the thigh bone that we can see in fossils like in T. Rex, suggesting that that muscle existed and probably was working in" "similar way in these forms." "What I am suggesting is that in" "Tyrannosaurus we have a unique combination of features, a tail that is more similar to what we see in crocodilians and yet a bird-like lower limb, so a bird knee, a bird ankle and a bird foot with a kind of crocodilian hips."" ""And so in Tyrannosaurus rex, I am predicting then we would have a unique combination of features working in a way unlike any other living animal today."" "T. Rex was huge and its tail enormous." "But it not only had to move, it had to mate." "Again, modern crocodiles may offer us a glimpse of the mechanics of T. Rex sex." "The examples of modern reptiles and birds, and a few rare fossils, suggest that T. Rex was a nesting animal and laid eggs." ""Well, I have in front of me some dinosaur eggs from China." "And these are very elongated, kind of the shape that we would expect for Tyrannosaurus rex." "To give you a feel for its size, I have here a chicken egg."" ""But what it is really exciting and very rare is this clutch of eggs here which are very badly crushed." "But we do have an embryo, and it is lying here." "We can see the eye socket, the skull, the backbone in here, the pelvis, a hind leg." "This embryo is about the size that we would expect for a Tyrannosaurus rex."" ""We can imagine this hatchling coming out of the egg and scurrying off into the underbrush or, possibly if there was parental care, it may have scurried off and joined its parents."" "Sixty-five million years ago the earth was ruled by the dinosaurs and the dinosaurs were ruled by Tyrannosaurus rex, a hunter fast enough, big enough, powerful enough to catch and consume any prey." "But one paleontologist dares to suggest T. Rex was not a killer but a scavenger, a giant marauding vulture." ""There is a controversy right now, um, of which I seem to be the, ah ha, to be one of and almost everyone else in paleontology seems to be at the other side of." "And this has to do with Tyrannosaurus rex being a predator or a scavenger." "A predator we have to remember is, is actually a hunter, and a scavenger is the kind of animal that only eats dead things."" ""We, we look down upon scavenging." "Tyrannosaurus rex." "We hate to think about Tyrannosaurus rex as a scavenger." "We would rather think of it as a predator." "It is named the tyrant lizard king." "You cannot have a king that is a scavenger."" ""A hunter should have big eyes." "It should have good eyesight." "And if we look at the brain case or if we look at, at, at a, ah, T. Rex, the biggest lobe of the brain, the actual big openings in the brain are for the sense of smell." "And, and because, because we, we can, we can actually carve out the area where the brain was, we can C AT scan it, we can do all sorts of things to it, we actually can make a model of what the brain would look like."" ""We see the optic lobe is right here." "It is very small." "And the olfactory lobe is this huge thing at the front end of the brain." "This is huge." "This is, this means that Tyrannosaurus had a very, very, very good sense of smell and not very good eyesight." "This is contradictory to a hunter." "This is what scavengers have."" "Horner's scavenger theory is disputed by Phil Currie, a stalwart defender of T. Rex, the hunter." ""The skull of Tyrannosaurus is very narrow in the snout region, which allows the eyes to face forward, giving it stereoscopic vision." "In addition to that, the ears themselves, um, are located in such a way that they should be able to pick up sounds in particular directions." "Ah, the ears may not look, ah, very different from the other carnivorous dinosaurs externally, but internally there are a lot of changes that have taken place."" ""This gives Tyrannosaurus rex a greater range of hearing capabilities, that is, the frequencies that it could hear were lower than what most other dinosaurs could." "Since Tyrannosaurus was probably hunting other dinosaurs which were animals that probably made low sounds, the changes in the ear would allow it to hear those animals better and to hunt them down."" ""The size of the Tyrannosaur is advantageous for a scavenger." "The bigger you are, the better chance you have of chasing away another animal that may have made a kill." "Even the short little arms are, T. Rex does not have anything for grabbing." "And we are bipedal." "We know that if we are going to go out and catch a chicken, we want, we do not want to have our hands tied behind us." "All of the features that we see all suggest that Tyrannosaurus and the" "Tyrannosaurs in general, were scavengers."" ""When I look in the jaws of Tyrannosaurus rex," "I have little doubt about its predatory capabilities." "These are jaws that are meant to do some pretty nasty work." "Like other carnivorous animals," "Tyrannosaurus rex has teeth that are curved backwards and at the same time the tips of the teeth, in fact, curve towards the center of the mouth as well." "What this means is that these teeth are specialized in such a way that if the prey is in the mouth and is struggling, ah, the only way for it to escape really is to go back further into the throat."" ""Because Tyrannosaur teeth are so tall, they have to have a very deep root." "And this give them, ah, the strength so that the tooth is unlikely to break and also has the strength to puncture right through bone." "And, ah, this is the reason the Tyrannosaurjaws are so deep." "Um, almost two-thirds the length of the tooth is, in fact, root."" "There are these very fine serrations that run down the front of the tooth and the back of the tooth." "These serrations function as little hooks, and as the tooth is driven through the meat, the hooks hook the fibers of meat and take it between the serrations." "And between the serrations you have razor-sharp edges that cut those fibers." "Now, if we shift to the inside of the jaw, we can see that there are some very powerful muscle attachments here going from the top down through this region." "And this gives a muscle mass that fills in this whole area." "These muscles allow the animal to close its jaws on very large animals and deliver a powerful bite very rapidly." "And it would have no trouble at all cutting an animal such as myself in half in one, single bite." ""We can say that Tyrannosaurus basically had a mouthful of steak knives." "And if you have a mouthful of steak knives, obviously, you eat steak, which is meat." "We know that Tyrannosaurs ate meat." "We know that they ate dinosaurs because we have evidence." "Yet this is a, a piece of a, a fibula, a shin bone from a duckbill dinosaur, and this shin bone actually has gauges, tooth marks from, from being bitten by a Tyrannosaur." "And what is really interesting, it has a puncture mark in it." "And in that puncture mark within the bone is actually the tip of a Tyrannosaur tooth." "So this is absolute proof that" "Tyrannosaurs ate meat, that they ate other dinosaurs." "But what it is not is evidence that the Tyrannosaur killed this particular animal."" "But Ken Carpenter's forensic examination of another duckbill provides more compelling evidence that T. Rex was a powerful, if not always successful, predator." ""I have been involved in a bit of detective work with this skeleton, mostly centered around the damaged area, this part of the tail." "If we look here, we will see that part of this, ah, spine is missing." "And it turns out that there is a very nice groove here that if I were to take a Tyrannosaurus tooth, we find that it fits very well in that groove." "Most likely then that this part of the vertebrae was bitten off by a" "Tyrannosaurus rex that was attacking from the right rear." "Now interestingly, we have regrowth of bone around this spine as well as around some of the tooth puncture marks on these adjacent ones, indicating that this animal survived the attack." "And the only animal that was big enough living at this time with jaws powerful enough to have sheared through this bone would have been a Tyrannosaurus rex." "And I think it shows conclusively that Tyrannosaurus rex was a predator and not a scavenger, as some have thought."" "For the past century, the Badlands of North America have gradually yielded the first clues to a great prehistoric puzzle, evidence of how T. Rex lived." "Many scientists are now convinced they have also uncovered the reason it died." "A narrow band of sediment marks the end of the Age of Dinosaurs and the beginning of the rise of mammals, the boundary between two geological epochs." ""Cretaceous-Tertiary boundary, ah, is well defined in this outcrop right here where we have been digging." "Well, the actual boundary is known from a very narrow band of clay that was laid down sixty-five million years ago." "We can, ah, recognize it on a global scale." "And it tells us that something very specific happened at that time, in geological time."" "There was a rare mineral called iridium, found in the clay." "It was carried here by an asteroid that smashed into the planet." "But did that actually cause the extinction of the dinosaurs?" "Certainly it seems to have had devastating effects." ""The fossil plants below the boundary tell us that there were lush forests existing in this region and, and throughout the prairie regions that we know, as we know them today before the boundary." "And right before the boundary in some sediments that, that I have studied, we have a very typical cypress swamp, such as the bald cypress swamp that you would find down in southern parts of the United States." "And above the boundary there are no cypress trees." "There is nothing in the, in those remains above the boundary that tell us the cypress swamps was around." "It was gone." "So something happened at that boundary that was very dramatic." "It leveled the forest." "The standing vegetation was, was literally clear-cut in a sense."" "Did this single catastrophe kill T. Rex?" "There are no fossils in the sediments immediately below the boundary, leading many to argue that the dinosaurs were extinct long before the asteroid impact." "But a newly-discovered footprint from New Mexico seems to indicate that the dinosaurs were still there." ""This is the, ah, layer with the, ah, youngest, ah, known dinosaur tracks." "They are only thirty-seven centimeters or so below this, ah, iridium layer." "That could be as little as, ah, a thousand years or less." "And what it indicates is that the dinosaurs in this region that made their footprints on this surface lived up until the very last minute." "They were not dying off slowly for hundreds of thousands or millions of years before the K-T event." "They survived until the eleventh hour, if you like."" "If Tyrannosaurus rex was around until the last moment, then it was witness to one of the most devastating events the world has ever seen, an environmental holocaust that not even the strongest of all the dinosaurs could survive." "The Badlands have surrendered a few of their secrets." "But many questions remain." "Hidden somewhere in these canyons are more clues to the ferocious life and mysterious death of the most powerful creature that ever walked the earth."