How did palaeontologists discover the age of the Tyrannosaurus rex named Sue?

How did palaeontologists discover the age of the Tyrannosaurus rex named Sue?

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I'm trying to understand how they discovered or speculated the age of Sue the Tyrannosaurus rex to be about 28-29 years old. How do they know exactly the age of Sue? Could it be wrong? Could it be possible that she is older then they thought - maybe 35 years old?

Dinosaur bones contain rings, similar to a tree, that can be counted to determine age. SUE was 28 when she died, making her the most geriatric Tyrannosaurus yet found. Her bones show signs of wear and even disease, including arthritis.

Paleontologists can make micron slices of bone and view the rings through polarized light, even on a microscope at 5-10x, similar to geologist mineral ID's.

Wiki: Growth lines may be deposited in synchrony with endogenous biorhythms. For example, captive crocodilians exposed to constant temperature, diet, and photoperiod, still exhibit the periodic and cyclical skeletal growth banding of their wild counterparts.[4] Consequently, it is assumed by many paleontologists that the growth lines of dinosaurs reflect annual rhythms, and that they may be used to determine individual ages. However, in the large and long bones of many dinosaurian taxa, resorption of internal and external bone proceeds even as new cortical bone continues to be deposited, so that growth lines deposited early in development may need to be inferred.">ShareImprove this answeredited Jun 16 '20 at 11:19Community1answered Jan 29 '18 at 10:09DeltaEnfieldWaidDeltaEnfieldWaid8,01714 silver badges32 bronze badges

Jack Horner (paleontologist)

John Robert Horner (born June 15, 1946) is an American paleontologist most famous for discovering and naming Maiasaura, providing the first clear evidence that some dinosaurs cared for their young. In addition to his paleontological discoveries, Horner served as the technical advisor for all the Jurassic Park films, [1] had a cameo appearance in Jurassic World, [2] and served as a partial inspiration for one of the lead characters of the franchise, Dr. Alan Grant. [3] [4] Horner studied at the University of Montana, although he did not complete his degree due to undiagnosed dyslexia, and was awarded a Doctorate in Science honoris causa. He retired from Montana State University on July 1, 2016 although he claims to have been pushed out of the Museum of the Rockies after having married an undergraduate student [5] [6] and now teaches as a Presidential Fellow at Chapman University.

The evolution of tyrannosaurs

‘Sue’ specimen of T. rex from the Chicago museum

T. rex is probably the most notorious and infamous dinosaur of all time, and somewhat of an icon in both the scientific and public spheres. After all, it was a pretty fearsome and impressive carnivore, and arguably worthy of such admiration. But there were actually a lot of other dinosaurs similar to T. rex, together forming a group known as tyrannosauroids.

Recently, a whole series of new findings is helping us to unlock the secrets of these fascinating beasts, and we can now begin to answer questions about their evolutionary relationships, biogeography, and how decent their fossil record is. In fact, half of all known tyrannosauroid species have been discovered in the last decade alone!

Tyrannosauroid species were actually around way before T. rex, which only occupied the top of the food chain right at the end of the Cretaceous reign of the non-avian dinosaurs. Actually, the largest tyrannosauroids only seemed to appear around 20 million years before this. Before they achieved such terrifyingly gigantic sizes, most were actually quite small-bodied (for a dinosaur), and quite ecologically diverse.

Steve Brusatte, Thomas Carr and their colleagues visited the question of the inter-relationships of tyrannosauroids back in 2010. Forming hypotheses of relationships like this forms the basis for assessing important evolutionary factors, such as the origins and evolution of particular anatomical features, rates of evolution, diversity, anatomical disparity, and biogeography. So when another study produced alternative results to their earlier study, Brusatte and Carr decided to go back to the Mesozoic and reanalyse tyrannosauroids, but incorporating all of the recent bits of knowledge we have gained about them over the last few years.

obtained using parsimony methods. Credit: Brusatte and Carr, 2016

In addition to this, Brusatte and Carr decided to approach this with a dual method. Typically, when palaeontologists create trees that form the basis of assessing evolutionary relationships, we use a method called parsimony. This looks at how many different anatomical changes have occurred between different species, and tries to provide the minimum number of changes in order to build a tree. They also decided to go Bayesian on their dataset though, something which hasn't really taken off in palaeontology yet, and has been more widely applied to molecular analyses. This works slightly differently by analysing anatomical data (in the form of a character matrix) in a probabilistic framework, and by using more complicated models that treat characters in different ways. By using this combination of techniques, it is possible to see which results are congruent, and therefore which conclusions can be best supported.

Fortunately for Brusatte and Carr, the results of both analyses were quite similar overall, lending support to their conclusions. There are slight differences, which you can see by comparing the two trees figured here. The overall structure reveals that tyrannosauroids can be sub-divided into a basal clade of proceratosauroids, which includes taxa such as the feathered Yutyrannus and Guanlong an intermediate grouping or grade of small- to medium-sized beasties and the gigantic apex predators such as T. rex and Tarbosaurus that we all know thanks to the best scientific minds in Hollywood.

The authors do a great job of trying to work out why their results differ slightly, but as always, the devil is in the details and it can be quite difficult to figure out. Part of the reason for some of the discrepancies might be to do with missing data – we can never fully sample every organism that has lived, and palaeontologists accept that limit of the fossil record. In the case of tyrannosauroids, there is a 20 million year gap in their fossil record from just before the time when the Western Interior Seaway covered much of North America. What this means is that animals simply weren't preserved in the right time in the right place to be preserved as fossils. Yet, at least. Discovering new tyrannosauroids from this gap might be critical in working out how more derived tyrannosauroids evolved during a clearly important time in their history.

obtained using Bayesian methods. Credit: Brusatte and Carr, 2016

But what does all of this mean then for the evolution of tyrannosauroids? Well, for starters, it shows that the evolution of their large body size appeared to happen more gradually, rather than a rapid burst. Accompanying this, it shows that bite forces increased incrementally too, and that their elaborate facial ornamentations gradually became more complicated along with increasing body size. The first truly gigantic tyrannosauroids, coming in at more than 1.5 tonnes in mass and 10 metres in body length, didn't appear in the fossil record until around 80 million years ago.

In terms of their biogeography, some interesting patterns emerge. It seems like there was episodic interchange between Asia and North America during the Late Cretaceous. What this means, and I'm sure Donald Trump will love this, is that T. rex actually appears to have been an Asian immigrant that colonised North America. However, this understanding might change as we recover ever more tyrannosauroid fossils from the latest Cretaceous of Asia and North America.

So, that's a quick update on what we know about tyrannosauroids. Despite them clearly winning a cross-dinosaur popularity contest, there is still much we can learn about these creatures, and only time and future exploration can tell what we'll discover!

S. L. Brusatte et al. Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms, Science (2010). DOI: 10.1126/science.1193304

Stephen L. Brusatte et al. The phylogeny and evolutionary history of tyrannosauroid dinosaurs, Scientific Reports (2016). DOI: 10.1038/srep20252

Meet Nanotyrannus, the dinosaur that never really existed

About 67 million years ago, in what is now north-west Montana in the United States of America, a dinosaur died.

How it died is unknown, but its death was recorded all the same. Over geological time, bone turned to rock. The skeleton was saved in stone.

In 2003, palaeontologists from the Burpee Museum of Natural History in Illinois retrieved it. Untouched by erosion at the surface and tectonic forces below, the fossilised skeleton was nearly complete, reaching 20ft (6m) long and 7ft (2m) tall.

With a skull full of sharp teeth and long hind limbs, it was clearly a predator. Its sex was unknown, but nevertheless its discoverers called it "Jane".

What was Jane? There were two possibilities.

Some thought she might be a Nanotyrannus, a kind of pygmy relative of the mighty 13m-long Tyrannosaurus rex. That would mean there were two species of tyrannosaurs roaming the forests of North America during the late Cretaceous

Others said Jane was a juvenile T. rex that died too young &ndash and that there was never any such species as Nanotyrannus. If that is true, then Jane can tell us what T. rex was like as a gangling, awkward youngster.

As many palaeontologists are coming to realise, to understand the Age of Dinosaurs, you first have to understand the age of the dinosaurs you are studying.

Jane is not the only fossil that might belong to Nanotyrannus.

In 1942, David Dunkle from the Cleveland Museum of Natural History in Ohio had unearthed a slightly compressed skull, similar in appearance to Jane's. It was labelled as CMNH 7541 and, for a long time, this is the only name that palaeontologists were sure of.

To understand the Age of Dinosaurs, you first have to understand the age of the dinosaurs you are studying

After poring over the skull's features, Charles W. Gilmore &ndash the doyen of tyrannosaur research at the time &ndash classified it as a species of Gorgosaurus. This was one of several smaller relatives of T. rex that lived during an earlier stage of the Cretaceous period.

However, in 1970 CMNH 7541 gained another moniker. A new study suggested it really belonged to a different tyrannosaur genus called Albertosaurus, named after dinosaur-rich deposits in Alberta, Canada.

Then in 1988, Bob Bakker of the University of Colorado and his colleagues changed the name again. They proposed that CMNH 7541 was something completely new among tyrannosaurs, a genus that no one had appreciated before. Based primarily on its thin face and small sharp teeth, they renamed the skull Nanotyrannus, literally translating as the "pygmy tyrant".

But even that was not the end of the story.

In 1999, using the excellent fossil record of Albertosaurus as a guide, Thomas Carr, now at Carthage College in Wisconsin, found that the skulls and teeth of tyrannosaurs became more robust over time.

Large dinosaurs &ndash just like other animals &ndash went through a remarkable sequence of sizes and shapes

Adults were big-boned, thick-toothed, and heavy, while juveniles and adolescents were sleek and lightly-built with thin teeth. In other words, the defining features of Nanotyrannus may have just been a sign of immaturity rather than a distinct identity.

Although backed by unprecedented detail and data, this idea was nothing new.

Working behind the borders of the USSR, the Russian palaeontologist Anatoly Rozhdestvensky first proposed that the Cleveland skull was just a juvenile T. rex in 1965, a time when it was still under its original name, Gorgosaurus.

Rozhdestvensky was one of the first palaeontologists to appreciate that dinosaurs changed dramatically in appearance as they grew &ndash something many of his contemporaries did not realise. After they hatched from their grapefruit-sized eggs, he realised, large dinosaurs &ndash just like other animals &ndash went through a remarkable sequence of sizes and shapes.

For instance, between 1941 and 1951 Chung Chien Young &ndash "the father of Chinese palaeontology" &ndash examined 70 specimens and managed to describe five new species of prosauropods early relatives of the sauropod group that includes giant herbivores like Diplodocus and Brachiosaurus.

Fossils can be misinterpreted as exciting evidence of a brand-new dinosaur species

However, when Rozhdestvensky looked through the same collection, he found only one: Lufengosaurus huenei. The other four "species" were actually just snapshots of L. huenei at different points in its development from egg to adult.

As Rozhdestvensky wrote in 1965: "Growth changes are therefore of the greatest importance in determining the scope and boundaries of a species."

As Carr laconically puts it: "Growth happens, and it changes everything." Without taking this fact into account, fossils can be misinterpreted as exciting evidence of a brand-new dinosaur species, when really they are just evidence of a known species at different ages.

"Just imagine if you found a skeleton of a toddler," says Stephen Brusatte of the University of Edinburgh in the UK. "If you knew very little about how humans grew, you might conclude that it was some pygmy primate species."

Although often ignored by western science during his time, Rozhdestvensky's thinking has now come to dominate dinosaur palaeontology.

"We just have a lot more knowledge about how dinosaurs grew," says Brusatte. "We recognise that when we find a new fossil and it's different from everything else, it could be a new species&hellip or, it could be just a growth stage of something already known."

Growth happens, and it changes everything

Thankfully, the dinosaur fossils themselves can help researchers decide between the two alternative interpretations.

Fossil bones contain a record of the annual rhythms of their owner's lives. Just like the rings of a tree, each year of growth is delineated against the next as growth halts in winter. This leaves a "line of arrested growth", or LAG. The number of rings provides an accurate proxy for the age at the time of death.

What's more, widely-spaced LAGs reveal that the dinosaur was growing quickly during that year, adding more bone before the harsh seasons arrived. In contrast, older dinosaurs had LAGs very close together in their final years of life. Their growing days were over.

Although researchers had the option of studying LAGs throughout the second half of the 20th Century, it only became commonplace in the last decade or so.

"It has taken so long to become really popular because of the idea that you actually have to cut a dinosaur bone to access this information," says Holly Ballard, assistant professor of anatomy at Oklahoma State University. "And a lot of people are very hesitant to do that, especially if you only have one specimen of that particular species."

But it is really not as bad as it sounds, Ballard says.

He estimated Jane's age at death as 12 years, give or take a year

First, only a tiny sample is needed &ndash a few millimetres will do the trick. And second, a replica piece, matching the original in shape and texture, can be made and reinserted back into the skeleton, making it appear whole once more.

The damage is minimal, but the rewards are great. Taking a slice of a non-weight-bearing bone is the best option, since any forces placed on bone can remodel its internal structure and blur any annual lines in the process.

That makes a fossilised skull &ndash a complex mosaic of different bones that are often subjected to extraordinary bite forces &ndash a poor choice. The Cleveland skull, therefore, remains ageless to science.

This is where Jane comes in. In 2003, Gregory Erickson of Florida State University in Tallahassee was given permission to take a small slice out of Jane's fibula the accessory shinbone to the weight-bearing tibia. After polishing the sample and placing it underneath a microscope, he estimated Jane's age at death as 12 years, give or take a year.

She was going through a growth spurt

That makes Jane a juvenile. Adult tyrannosaurs attain maturity at around 20 years of age, and lived until their early 30s.

In theory, Jane could have belonged to an unusual species of tyrannosaur with an exceptionally short lifespan. But it seems unlikely. In the years just before her death, Jane's annual growth rings were very far apart and the microstructure of the bone was highly porous, indicative of blood vessels nourishing the cells that secreted the bone.

In other words, she was nowhere near a fully-grown adult when she died. Instead, she was going through a growth spurt.

In 2005, after slicing through the bones of adult T. rex specimens, Erickson demonstrated exactly how this species grew to be a giant among giants. After comparing their LAGs to the smaller &ndash but still 33ft (10m) long &ndash Albertosaurus and Gorgosaurus, he demonstrated that tyrannosaurs all seemed to go through a growth spurt that lasted for about 10 years.

I have my whole life to decide whether I think Nanotyrannus is a T. rex

The difference was the rate. While the smaller species were struggling to put on 1lb (500g) of weight per day, T. rex was adding over 4lb (2kg). That is like adding a classic Mini Cooper, complete with driver and a passenger, in mass every year.

"There's this huge boost in growth through the teenage years," says Tom Williamson of the New Mexico Museum of Natural History and Science. "It's much greater than what you see in other tyrannosaurs. It's just more. With T. rex, everything is more."

From deep within her bones, Jane's true identity had started to emerge. If she had not died when she did, she would probably have become a giant herself. "[Jane] would fit right in with being a T. rex," says Erickson.

But he is still reluctant to conclude that Jane really was just a juvenile T. rex &ndash and that Nanotyrannus never existed as a separate species. "I have my whole life to decide whether I think Nanotyrannus is a T. rex," says Erickson. "And on my deathbed I may not even make a decision."

However, other palaeontologists are more confident in the evidence.

Carr is currently working on a monograph of the Jane specimen, detailing its every nook and cranny and profiling her features. Taken as a whole, he finds little evidence that Jane could be anything but a young T. rex.

"You have to work really hard at ignoring all of the evidence that shows that it's a juvenile and that, in terms of identity, it's T. rex," he says. "You have to close your eyes and plug your ears."

Brusatte agrees. "Jane, no doubt, is a juvenile," he says. "Absolutely no doubt. Some people have argued that it's not, which is insanity. When that monograph comes out it will mostly shut the book on Nanotyrannus."

That means Jane provides a rare glimpse into an iconic giant's early years as a smaller predator.

She was in an "awkward gangly teenage phase"

"The fossil record was really poor for young tyrannosaurs," says Carr. "And Jane is virtually complete. [She] will help set out the growth changes of how we get from a juvenile to a full adult."

Even without a monograph, many changes are obvious with little more than a cursory glance at the skeleton. Unlike the thick bones and deep skulls of adulthood, Jane's skeleton is lightly-built, sleek, and long-limbed.

Within her skull, her teeth are thin and serrated like steak knives. Jane would have been an agile hunter, more akin to a large raptor than her older kin. She was in an "awkward gangly teenage phase," says Brusatte.

She may also have been clad in a coat of feathers. The fossils of T. rex's ancestors show the trademark imprints of simple hair-like outgrowths covering large portions of the body, more akin to the coat of New Zealand's kiwi than a New Caledonian crow. "The only logical conclusion is that T. rex itself had feathers," says Brusatte.

The adult T. rex was such a freak of evolution, or a feat of evolution

Jane's early death is a metaphor for her entire species. "T. rex was the James Dean of dinosaurs," says Erickson. "These things lived fast and died young."

During a decade of adulthood, T. rex was the size of a double-decker bus. Its jaws and teeth could crunch through bone, inflicting deep gouges into the skulls of adolescent Triceratops &ndash as well as the faces of other T. rexes.

"The adult T. rex was such a freak of evolution, or a feat of evolution," says Brusatte. "Whatever you want to call it, it's really both. But understanding how that adult grew, how it developed, what it had to go through to get to that stage of being seven tonnes, 13 metres long&hellip That's a fascinating biological, anatomical question. And we're really getting at it. That's really amazing. That's what we should be revelling in."

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Scientists Uncover Some Answers

It was often a mystery to scientists and paleontologists how the region&rsquos Tyrannosaurus Rexes grew to be the incredible animals they were. That is due to the major gap in North America&rsquos mid-Cretaceous fossil record. At the foundation of the era, Tyrannosaurs were nowhere near the size they are known for today. Instead of the large, intimidating animals with scary teeth and jaws, they were relatively small and often scrappy predators. Previously they did not hunt alone, but rather, they hunted alongside the larger carnivorous dinosaurs that are now known as allosaurus. Much is unknown about these incredible animals, but scientists do know they were not always their enormous size.

Photo Credit: Brigos Art Station

Approximately 80 million years ago, the North American allosaurus faded into the background, and Tyrannosaurs grew tenfold. Tyrannosaurs evolved so much that they took the allosaurus&rsquo place as the top predator. The tiny fossils of Moros intrepidus suggest that North American Tyrannosaurs stayed small until at least the time that Moros appeared. It would mean that Tyrannosaurs grew into their famous sizes in just 16 million years. For paleontologists, this is considered a sprint in evolution. Paleontologists had been searching in the area for roughly ten years, and the bones of Moros intrepidus were the only ones that were recovered. It required a lot of patience, time, and an even more amount of luck.

The fossils allow paleontologists to learn more about dinosaurs. Photo Credit: Haaretz

Fossil regulation before Sue

In 1984, the National Academy of Sciences formed the Committee on Guidelines for paleontological collecting in response to this increasing interest in fossils from various stakeholders (Raup et al. 1987). The committee included thirteen members ranging from academic vertebrate and invertebrate paleontologists to fossil dealers, industry representatives, as well as state and federal government officials. Their objective was to discuss the protection, preservation, access to, and ownership of vertebrate and invertebrate fossil material. Specifically, they sought to “to develop a general statement on the appropriate role of government in the regulation (or lack thereof) of field collecting of the fossils of prehistoric plants and animals” (Raup et al. 1987, vii). Footnote 10 Much of their discussions were about existing assumptions regarding the definition and significance of fossils. They also shared thoughts on who should have the authority to access them.

As far as the committee was concerned, they were asking an “apparently straightforward question” (Raup el et al. 1987, 216). “How should government protect and preserve fossils of extinct plants and animals while at the same time allowing other legitimate uses of the land and encouraging the scientific study of fossils?” (Raup el et al. 1987, 216). The answer was far from simple for three reasons.

First, there was no federal law regarding the collection of paleontological material on public land. Consequently, the authority to employ and enforce policies concerning fossil collection fell to numerous federal land management agencies such as the Bureau of Land Management (BLM), the National Park Service (NPS), and Forest Service (FS). Footnote 11 These agencies had authority to determine who was allowed to collect fossils via use of issued permits or other regulatory protocol. This also meant that fossil collectors—scientists, hobbyists, and dealers alike—were responsible for educating themselves of these policies if there were any, and understanding their disparities so to abide accordingly. Doing so could be a near impossible task. Indeed, there were more than sixty federal agencies with some form of regulatory responsibility concerning fossil collection on public land (Raup el et al. 1987, 2). For the most part, however, these agencies had no specific policies and if they did, they were inconsistent, ambiguous, or difficult to enforce.

Next, the committee noted that several government agencies held what were erroneous or problematic assumptions about paleontological practice. Footnote 12 For example, most agency officials assumed that paleontological material could be regulated in the same way as archeological material, the latter for which there was a clear-cut law. The Antiquities Act of 1906 specified how archeological sites and specimens on land owned or controlled by the government were to be protected for the natural and cultural heritage of the United States. The act did not specifically speak to fossil remains in the way that it addressed archeological artifacts, but it had been used to justify the arrest and trial of Farish Jenkins, a Harvard University paleontologist accused of illegally collecting fossils on public land. Footnote 13 According to the committee, this was but one example of “overzealous regulatory activities of federal agencies”—much of which was a result of a misunderstanding of the differences between archeological and paleontological material (Raup el et al. 1987, 2). Footnote 14 They also argued the need for a legal understanding of the difference between archeological and paleontological material in order to avoid future issues. Interestingly, this case was not an isolated instance in which government officials assumed likeness between paleontological and archeological material. In 1992, the federal government cited the Antiquities Act of 1906 to justify the FBI’s actions in confiscating Sue from the BHI.

Lastly, the committee claimed that the paleontology community held assumptions regarding the incompatibility of scientific and commercial interests, thus further problematizing the subject of fossil access. As far as the committee was concerned, commercial fossil collection was “one of the most sensitive and difficult aspects of the overall problem” (Raup el et al. 1987, 5). For the committee’s purposes, they defined commercial fossil collection as the general collecting, buying, and selling of paleontological material with other dealers or hobbyists on a national or international scale. They often traded or sold their finds to private individuals as well as public groups such as schools, universities, museums. A number of academics, explained the committee, vehemently opposed the selling fossils for economic gain as a matter of principle. The committee’s final report, for example, noted that “[m]any paleontologists find the sale of fossils repugnant on esthetic and moral grounds and because the increasing use of spectacular fossils as art objects encourages over-collecting of rare species” (Raup el et al. 1987, 5). Footnote 15 In this same report, committee members highlighted the positive impact of commercial collectors, explaining that fossil dealers were concerned with advancing the education and production of knowledge in paleontology, thus meeting both personal economic and public educational interests (Raup el et al. 1987, 12–13). Across government agencies and the paleontology community, there were different assumptions concerning a fossil’s value and a commercial collector’s intentions regarding their access to it.

After a 3-year discussion and a 200-page report of serious “soul-searching,” the committee concluded that in regards to fossil collection and preservation on federal land that the “science of paleontology” would be “best served by unimpeded access to fossils and fossil-bearing rocks in the field” where “‘access’” was defined to include “all collecting and removal of fossiliferous material for study and preservation” (Raup el et al. 1987, 2). In other words, it appeared the committee was in favor of reducing rather than promoting regulation in order to encourage fossil access. However, they were quick to note that this stance did not imply a deliberate disregard for paleontological protections: “If taken out of context, these recommendations carry the unfortunate implication that the Committee members do not think fossils are important enough to ‘protect and preserve.’ Nothing could be further from the truth. We all recognize and appreciate the great importance of fossils both to science and to society, but we also realize that an uncollected and unstudied fossil is of no value” (Raup el et al. 1987, 3).

Rather than supporting more regulations, they offered the following recommendations. First, they supported a uniform federal policy, although not necessarily a law, on paleontological collecting. They were also in support of the idea that each state should adopt a uniform policy for collecting on state-owned land. The third recommendation suggested that all federal land should be available for scientific collecting without a permit, and that activities regarding quarrying or commercial collecting should also be allowed but with permit permission. Finally, the committee suggested that any scientifically significant fossil must be reported, then deposited in an appropriate public institution (Raup el et al. 1987, 3–4).

This conclusion was an effort to balance the interests of academics, amateurs, commercial collectors, and the general public in terms of fossil access while simultaneously protecting the fossils themselves as natural, nonrenewable resources. In the end, however, the Secretary of Interior “disregarded the recommendations” altogether. The Secretary was reportedly of the opinion that “‘fossils do not constitute a resource requiring the degree of management attention initially proposed by the Department [of Interior]’” (Malmsheimer and Hilfinger 2003, 603). Despite the committee’s efforts, there was no change in law or even policy. Regulation was left to federal government agencies, and stakeholders were left to make sense of the policies, including their ambiguities. At the time of Sue’s discovery in 1990, this was the landscape of political assumptions that informed her significance and led to a decade-long custody battle over her ownership.

SUE the T. rex

Get to know the dinosaur known as Specimen FMNH PR 2081.

You may know SUE as the hilarious, pun-loving dinosaur turning Twitter into a personal smorgasbord. Or you might treasure that selfie you snapped with this fearsome fossil looming overhead. But there’s a lot more to SUE’s story than 280 characters or a passing glance might offer.

This specimen has been invaluable to the paleontological community since its discovery. And before settling into the luxurious life of a well-kept Chicago museum attraction, SUE had quite the history!

Dating back to the Cretaceous period—about 67 million years ago—this massive predator lived to the upper end of the life expectancy of a T. rex, about 28 years. (How do we know? Dinosaur bones have growth rings, just like trees. After examining these rings, scientists also determined that SUE had an adolescent growth spurt—gaining as much as 4.5 pounds per day—and reached full size at age 19.)

SUE’s sex is unknown this T. rex is named for Sue Hendrickson, who discovered the dinosaur in 1990 during a commercial excavation trip north of Faith, South Dakota.

Hendrickson spotted a few large vertebrae jutting out of an eroded bluff and followed her hunch that there were more beneath the surface. In the end, it took six people 17 days to extract the dinosaur’s bones from the ground where SUE was discovered.

Susan Hendrickson stands near her discovery.

© The Black Hills Institute, courtesy of Peter Larson

After excavating the fossilized bones, collectors wrapped the bones in protective plaster field jackets to remove them from the site.

© The Black Hills Institute, courtesy of Peter Larson

How did SUE get to the Field Museum?

Shortly after Hendrickson’s landmark discovery, three parties embarked on a five-year custody battle that ended in a public auction in 1997. The highest bidder? The Field Museum (with support from McDonald’s Corporation, the Walt Disney World Resort, and private donors), at a staggering $8.4 million—the most money ever paid for a fossil at auction.

SUE finally made a dramatic debut in Stanley Field Hall on May 17, 2000, but there was a lot of work to be done to get the skeleton there. After SUE was purchased at auction, 12 museum preparators spent more than 30,000 hours preparing the skeleton (plus another 20,000 hours building the exhibit).

Why is SUE so important?

At more than 40 feet long and 13 feet tall at the hip, SUE is physically the largest Tyrannosaurus rex specimen discovered, out of more than 30 T. rex skeletons that have been found. SUE is also the most complete—around 90 percent. We have 250 of the approximately 380 known bones in the T. rex skeleton, including the furcula (wishbone) and gastralia (a set of rib-like bones stretched across the dinosaur’s belly, believed to have helped SUE breathe).

Copies of SUE’s skeleton were created from molds made by our preparators. These casts were made for a variety of purposes. One complete skeleton is stored unassembled in our research collections for further study by visiting scientists. Others were assembled into mounted cast skeletons, which travel to museums and science centers around the world for international dinosaur lovers to marvel at.

All that expense and hard work has been well worth it: SUE is the most celebrated representative of T. rex and arguably the most famous fossil in the world. SUE has enabled scientists all over the world to do more detailed studies of the species’ evolutionary relationships, biology, growth, and behavior than ever before.

SUE lived in the Late Cretaceous period, depicted here in a painting by John Gurche.

What SUE has taught us

SUE has taught scientists about biomechanics and movement, dinosaurs’ intellect, and even how much SUE weighed, says Peter Makovicky, the Field Museum’s curator of paleontology. Other fossils discovered during the same excavation can also tell us about the environment SUE lived in, what the dinosaur ate, and more.

“All of this can tell a very powerful, very vivid story to the public that gives insight into how science is done,” Makovicky says. “There are questions about biology of dinosaurs—and Tyrannosaurus in particular—that you can only answer with SUE.”

For example: How did T. rex use their arms?

In 2016, one of SUE’s tiny forelimbs took a solo field trip to Argonne National Laboratory in Lemont, Illinois, where researchers took micro-CT scans of the arm to produce high-resolution images of its interior. Those scans allowed us to get a look at SUE’s bone structure—and study how our favorite dinosaur used its arms.

SUE’s skull alone has fascinated researchers for decades.

The skeleton’s skull is a cast, with the real one displayed in a freestanding case for easy access to visiting scientists. (It also weighs 600 pounds!) Much research has centered around telltale holes in SUE's lower jaw. Some scientists used to believe the holes were bite marks, but it's now more widely accepted that they were caused by a infection. (Dinosaurs: They’re just like us!)

“It’s fun to open the case with SUE’s skull inside and study this specimen in front of the public,” Makovicky says. “These things aren’t just out in the hall to be looked at.”

SUE’s skull is displayed separately from the rest of the skeleton, allowing scientists easier access.

Scotty: the dinosaur skeleton which is a contender for the largest T. rex ever

In March 2019, a Tyrannosaurus rex made headlines 66 million years after it had died. Was its skeleton the largest of its kind ever discovered?

Dubbed "Scotty", the skeleton had been discovered in Saskatchewan, Canada. In fact, these bones had been unearthed decades before. They were found in 1991, by then-school teacher Robert Gebhardt, but were so deeply encased in sandstone that it has taken decades to painstakingly remove them.

Until now, the largest T. rex skeleton known to science was that of "Sue". It was uncovered in South Dakota, USA, on 12 August 1990, by explorer and fossil collector Sue Hendrickson, after whom it was named.

On 4 October 1997, Sue's skeleton sold at auction for $8.3 million (£5.1 million) to The Field Museum in Chicago, Illinois, USA, becoming the most expensive dinosaur bones.

So how do Scotty and Sue size up?

Unfortunately, it's practically impossible to make a direct comparison, as the two specimens are not equally whole. Sue is approximately 90% complete, compared to 65% for Scotty – indeed, Sue is the most complete T. rex skeleton – comprising 250 of the 380 bones that the body would have featured. That also makes it possible to calculate this dinosaur's original size – 12.5 m (41 ft) long and 4 m (13 ft) tall at the hip – fairly precisely.

From what we can tell, Scotty was probably slightly longer – perhaps up to 13 m (42 ft 7 in), according to the University of Alberta's Dr W Scott Persons, who led a study into calculating Scotty's dimensions.

But scientists always allow a margin of error when comparing such ancient skeletons, and it's likely that it may not have been demonstrably longer or taller than Sue. The research estimates that Scotty weighed in the region of 8,870 kg (19,555 lb), around 410 kg (900 lb) heavier than Sue, which would make it the most massive T. rex ever discovered. (That's around two-and-a-half times the weight of a white rhino – the largest rhinoceros.)

But again, by factoring in a degree of scientific leeway, Scotty may not have outweighed Sue by a significant amount. Longer dinosaurs weren't always heavier than shorter ones.

"There are many different approaches to estimating dinosaur size," Dr Persons explains. "You could try making a scale model of what you think the dinosaur looked like in the flesh, directly calculate the mass of your model, and then scale your calculation up. You could create a 3D scan of the dinosaur's entire skeleton and model the flesh over it.

"But that technique only works if you have a very complete skeleton (better for Sue than Scotty). Both of these approaches involve many assumptions about what the missing flesh would have been like."

An alternative approach, and one adapted by Dr Persons and his team, is to estimate the animal's size based on the leg bones. "The legs of T. rex were the pillars that held the mighty dinosaur up. It makes sense that the girth of those pillars would correlate with the amount of weight they were adapted to support.

"Based on the strength of Scotty's leg bones, we have calculated the dinosaur's weight at roughly 8,800 kg [19,400 lb]. But take that mass lightly, because such leg-based estimations are not an exact science. Perhaps Tyrannosaurus rex put extra pressure on its legs, because it frequently chased after fast prey. If so, its leg bones may be evolutionarily overengineered. So, our number could be off by a few tons!"

Until palaeontologists reach a definitive and universally accepted decision, then, Guinness World Records (GWR) believes that Scotty and Sue should jointly share the title of largest T. rex skeleton.

Dr Persons was delighted when we contacted him about the new joint record, adding: "I hope the honour will draw attention to the very cool work being done in the fossil-rich badlands of Saskatchewan. Excavating, cleaning and studying Scotty's enormous skeleton has been a correspondingly tremendous undertaking.

"I am delighted to have been part of a huge team of researchers, volunteers and expert diggers that has dedicated years towards exhuming the dinosaur."

Scotty and Sue may have male and female nicknames, but in reality scientists struggle to accurately determine dinosaur gender. "Determining the sex of prehistoric mammals is usually much easier," Dr Persons tells us.

"Because most mammals give live birth, females tend to have diagnostically wider hips. But dinosaurs seem to have all been egg layers. Big dinosaurs, like T. rex, laid relatively small eggs, which required hip bones of no greater width or unique form."

Recently, palaeontologists have experimented with a different sexing technique, based on mother birds. When they're preparing themselves to produce eggs – the shells of which will need calcium – they produce a calcium-rich layer of bone ("medullary bone") inside thicker parts of their skeleton, such as the legs. None was found in Scotty.

"Now, this does not prove that Scotty was a 'him'," acknowledges Dr Persons. "Unfortunately, medullary bone doesn't stick around for very long. It is only present at and near the time of egg laying. So, while the presence of medullary bone would prove that a dinosaur is female (because only females ever produce eggs), its absence only proves that the dinosaur wasn't pregnant when it died.

"Scotty's gender identity remains ambiguous. And I'm cool with that."

Find out about more record-breaking animals in our records showcase

The name Tyrannosaurus rex literally means "tyrant lizard king", a reference to this apex predator's fearsome reputation. One of the largest prehistoric carnivores, it lived during the Late Cretaceous period, 67–65 million years ago.

T. rex mainly populated forests and river plains in prehistoric North America, although in 2012 fossils of one of its ancestors, the feathered Yutyrannus huali, were discovered in north-eastern China.

Recent research into the size and weight of T. rex suggests that it moved less speedily than previously thought, walking rather than running at around 19 km/h (12 mph) – although its prey was usually even slower. So that classic scene from Jurassic Park (USA, 1993) when the jeep is being chased probably had longer to get away from the pursuing dinosaur than we once thought!

By contrast, the fastest dinosaur was the ostrich-like Gallimimus, which scientists believe could maintain speeds of 60 km/h (35 mph). It would comfortably outpace Jamaica's Usain Bolt, who reached a top speed of 44.16 km/h (27.44 mph) during his record-breaking fastest 100 m run in 2009.

T. rex had up to 60 conical, serrated teeth, each about the size of a banana, and could bite with a force of up to 57,000 N (12,814 lb/f) – the strongest land-animal bite ever. To put that in context, it's five times greater than the canine bite of a saltwater crocodile (the strongest caniniform bite force for a crocodile today).

The "tyrant lizard king" mostly hunted herbivorous dinosaurs such as Triceratops and Edmontosaurus, although one study from 2010 also suggested that it willingly fed on its own kind as well. Given the need to eat whenever possible, it probably hunted live prey but also scavenged too. But there’s much that is still unclear about its dining habits – for example, whether it was a lone hunter or attacked in packs.

While it may better known than most of its prehistoric peers, T. rex wasn't the largest carnivorous dinosaur. That title goes to Spinosaurus. Analysis of skull fragments suggests that it grew to 17 m (56 ft) in length and weighed up to 9 tonnes (19,850 lb). Indeed, Spinosaurus may well have been the largest terrestrial predator ever known.

It would never have had a prehistoric face-off with the tyrant lizard king, though: by the time T. rex was stomping the Earth, Spinosaurus had been extinct for 10 million years.

In evolutionary terms, T. rex didn't have long left either, though. Around 65.5 million years ago, a massive extinction event abruptly wiped out all the dinosaurs (except for the birds) along with about half of all animal species.

Scotty and Sue must have been remarkably strong, and resilient, to live as long as they did. Both specimens were of a similar age when they died, although Dr Persons believes that Scotty edges it as the oldest known T. rex, perhaps having reached 30-plus years old. That makes them old for their species.

Dinosaurs were constantly engaged in an often-violent struggle for survival and many didn't get past their first year. The bones of Scotty and Sue bear enough teeth marks to suggest that they'd each weathered plenty of attacks during their long lives. Scotty had poorly healed ribs, an infected jaw and possibly a tail bite from another T. rex.

It's unlikely that those injuries killed him, though. "They are old scars and all from battles the T. rex survived," Dr Persons says. "I cannot say what killed Scotty, that remains a mystery. Although I can tell you that Scotty's skeleton records none of the bite marks that would have been left by other carnivorous dinosaurs munching and gnawing on its bones. In the end, Scotty was not another dinosaur's meal."

To date, some 50 partial T. rex skeletons have been discovered. But until a truly unprecedented specimen is discovered, these two tyrannosaurs remain GWR title holders as the largest of their kind.

So how likely is it that we'll find an even larger, or more complete skeleton?

"Very likely," Dr Persons affirms. "As a species, Tyrannosaurus rex roamed across the whole of western North America, for over a million years. I find it impossible to think that we have been so lucky as to discover the two largest individuals that ever lived. There must be even bigger (though probably just slightly) T. rex skeletons waiting to be found.

"As Scotty illustrates, world records are made to be broken."

Unearth a whole chapter on record-breaking dinos in Guinness World Records: Wild Things – out now!

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Newly found species reveals how T. rex became king of dinosaurs

The remains of a new species of horse-sized dinosaur reveal how Tyrannosaurus rex became one of Earth's top predators, a study suggests.

The discovery unearthed in Uzbekistan provides key insights into how a family of small-bodied dinosaurs evolved over millions of years to become fearsome giants.

The study shows that the dinosaurs -- known as tyrannosaurs -- developed huge body sizes rapidly right at the end of the age of dinosaurs, and that their keen senses, which evolved earlier in much smaller species, enabled them to climb to the top of the prehistoric food chain.

Until now, little was known about how tyrannosaurs became the giant, intelligent predators that dominated the landscape around 66 million years ago.

The newly discovered species -- named Timurlengia euotica -- lived about 90 million years ago, the team says. It fills a 20 million year gap in the fossil record of tyrannosaurs, and provides key insights into how the family evolved.

A team of palaeontologists, led by researchers at the University of Edinburgh, studied a collection of tyrannosaur fossils found in the Kyzylkum Desert, northern Uzbekistan.

The species' skull was much smaller than that of T. rex, indicating that it did not grow to the same enormous size. However, key features of Timurlengia's skull reveal that its brain and senses were already highly developed, the team says.

Timurlengia was about the size of a horse, and could weigh up to 250kg. It had long legs and a skull studded with sharp teeth, and was likely a fast runner, researchers say.

The first tyrannosaurs lived around 170 million years ago and were only slightly larger than a human. However, by the late Cretaceous Period -- around 100 million years later -- tyrannosaurs had evolved into animals like T. rex and Albertosaurus, which could weigh more than 7 tonnes.

The fact that the new species was still small some 80 million years after tyrannosaurs first appeared indicates that huge size developed only at the very end of the group's evolutionary history, the team says.

The study, published in the journal Proceedings of the National Academy of Sciences, was funded by the European Commission, National Science Foundation, National Geographic Society and the Russian Scientific Fund Project. The work was carried out in collaboration with researchers at the Russian Academy of Sciences, Saint Petersburg State University and the National Museum of Natural History, Smithsonian Institution, US.

Dr Steve Brusatte, of the University of Edinburgh's School of GeoSciences, who led the study, said: "The ancestors of T. rex would have looked a whole lot like Timurlengia, a horse-sized hunter with a big brain and keen hearing that would put us to shame. Only after these ancestral tyrannosaurs evolved their clever brains and sharp senses did they grow into the colossal sizes of T. rex. Tyrannosaurs had to get smart before they got big."

Professor Hans Sues, of the National Museum of Natural History, Smithsonian Institution, said: "Timurlengia was a nimble pursuit hunter with slender, blade-like teeth suitable for slicing through meat. It probably preyed on the various large plant-eaters, especially early duck-billed dinosaurs, which shared its world."

Professor Alexander Averianov, of Saint Petersburg State University, said: "The middle Cretaceous is a mysterious time in evolution because fossils of land-living animals from this time are known from very few places. Uzbekistan is one of these places. The early evolution of many groups like tyrannosaurs took place in the coastal plains of central Asia in the mid Cretaceous."

Watch the video: Tyrannosaurus rex facts. Interesting facts about t rex (August 2022).