Category Archives: theropods

April 6, 2014 · 5:56 pm

Displaying the Tyrant King – Part 2

Old meets new

Old meets new: The classic Carnegie T. rex (CM 9380) is now paired with a cast of Peck’s Rex (MOR 980). Photo by the author.

Start with Displaying the Tyrant King – Part 1.

In 1915, the American Museum of Natural History unveiled the first mounted skeleton of Tyrannosaurus rex ever constructed. The Carnegie Museum of Natural History followed suit with their Tyrannosaurus mount in 1941, and for most of the 20th century New York and Pittsburgh were the only places in the world where the tyrant king could be seen in person. Nevertheless, these displays propelled Tyrannosaurus to universal stardom, and the instantly recognizable dinosaur appeared in countless books, films, and other media for years to come.

The omnipresence of T. rex was secured in part by two additional museum displays, ironically at institutions that did not have any actual Tyrannosaurus fossils on hand. The Field Museum of Natural History commissioned Charles Knight to paint a series of prehistoric landscapes in 1928, the most recognizable of which depicts a face-off between Triceratops and a surprisingly spry Tyrannosaurus. In 1947, Rudolph Zallinger painted a considerably more bloated and lethargic T. rex as part of his Age of Reptiles mural at the Peabody Museum of Natural History. Both paintings would be endlessly replicated for decades, and would go on to define the prehistoric predator in the public imagination.

Rex Renaissance

Despite enduring public enthusiasm, scientific interest in dinosaurs declined sharply in the mid-20th century, and new discoveries were few and far between. This changed rather suddenly with the onset of the “dinosaur renaissance” in the 1970s and 80s, which brought renewed energy to the discipline in the wake of evidence that dinosaurs had been energetic and socially sophisticated animals. The next generation of paleontologists endeavored to look at fossils in new ways to understand dinosaur behavior, biomechanics, ontogeny, and ecology. Tyrannosaurus was central to the new wave of research, and has been the subject of hundreds of scientific papers since 1980. More interest brought more fossil hunters into the American west, leading to an unprecedented expansion in known Tyrannosaurus fossils. Once considered vanishingly rare, Tyrannosaurus is now known from over 50 individual specimens across a wide range of ages and sizes. Extensive research on growth rate, cellular structure, sexual dimorphism, speed, and energetics, to name but a few topics, has turned T. rex into a veritable model organism among dinosaurs.

RTMP 81.6.1, aka Black Beauty, mounted in relief at the Royal Tyrell Museum. Source.

RTMP 81.6.1, aka Black Beauty, mounted in relief at the Royal Tyrell Museum. Source

The most celebrated Tyrannosaurus find from the early years of the dinosaur renaissance came from Alberta, making it the northernmost and westernmost T. rex to date. The 30% complete “Black Beauty” specimen, so named for the black luster of the fossilized bones, was found in 1980 by a high school student and was excavated by paleontologist Phil Curie. The original Black Beauty fossils were taken on a tour of Asia before finding a permanent home at the newly established Royal Tyrell Museum in Drumheller, Alberta. In lieu of a standing mount, Black Beauty was embedded in a faux sandstone facade, mirroring the environment in which the fossils were found and the animal’s presumed death pose. This relief mount set Black Beauty apart from its AMNH and CMNH predecessors, and even today it remains one of the most visually striking Tyrannosaurus displays.  Since the original specimen consisted of less than half of a skeleton, much of this display is made up of sculpted bones, including the pelvis, scapula, and most of the ribs. The mounted skull is a cast, but the real skull is displayed behind glass nearby. A complete cast of Black Beauty in a traditional free-standing mount is also on display at the Swedish Museum of Natural History in Stockholm.

The World’s Most Replicated Dinosaur

Driven by the increased public demand for dinosaurs, many museums without Tyrannosaurus fossils of their own have purchased complete casts from other institutions. In 1986, the Academy of Natural Sciences in Philadelphia opened “Discovering Dinosaurs”, the world’s first major exhibit showcasing active, endothermic dinosaurs. The centerpiece of the exhibit was a cast of the original AMNH Tyrannosaurus, posed for the first time in the horizontal posture that we now know was the animal’s habitual stance. The following year, another AMNH cast appeared in the lobby of Denver Museum of Nature and Science in a strikingly bizarre pose, with one leg kicking high in the air. The mount’s designer Robert Bakker intended to push boundaries and demonstrate what a dynamic and energetic Tyrannosaurus might be capable of, although the mount has subsequently been described as dancing, kicking a soccer ball, or peeing on a fire hydrant. Meanwhile, The Royal Tyrell Museum prepared a mount of RTMP.81.12.1 (a specimen consisting of a relatively small number of postcranial bones) that was filled in with AMNH casts, including the highly recognizable skull.

Cast

Tyrannosaurus cast at the Denver Museum of Nature and Science. Source

Since the late 1990s, however, casts of another specimen have overtaken AMNH 5027 for the title of most ubiquitous T. rex. BHI 3033, more commonly known as Stan, was excavated in South Dakota in 1992 by the Black Hills Institute, a for-profit outfit specializing in excavating, preparing, and mounting fossils. Stan is significant for being over two-thirds complete and for including the best-preserved Tyrannosaurus skull yet found. BHI has sold dozens of casts of the Stan skeleton to museums and other venues around the world. At a relatively affordable $100,000 plus shipping, even small local museums and the occasional wealthy individual can now own a Tyrannosaurus mount. With over 50 casts sold as of 2017, Stan is, by a wide margin, the most duplicated and most exhibited dinosaur in the world.

Stan the Tyrannosaurus at the National Museum of Natural History. Photo by the author.

Stan the Tyrannosaurus at the National Museum of Natural History. Photo by the author.

All these new Tyrannosaurus mounts are forcing museums to get creative, whether they are displaying casts or original fossils. Predator-prey pairings are a popular display choice: for example, the Houston Museum of Natural Science T. rex is positioned alongside an armored Denversaurus, and the Los Angeles Natural History Museum matches the tyrant dinosaur with its eternal enemy, Triceratops. Meanwhile, the growing number of juvenile Tyrannosaurus specimens has allowed for family group displays. A second T. rex exhibit at LACM features an adult, subadult and baby, while the Children’s Museum of Indianapolis pairs a Stan cast with the original skeleton of Bucky, a “teenage” T. rex. The most unique Tyrannosaurus mount so far is certainly the copulating pair at the Jurassic Museum of Asturias.

Tyrannosaurus versus Denversaurus at the Houston Museum of Nature and Science. Photo by the author.

Each of these displays gives a substantially different impression of Tyrannosaurus. Depending on the mount, visitors might see T. rex as a powerful brute, a fast and agile hunter, or a nurturing parent (or a gentle lover). Each mount is accurate insofar that a real Tyrannosaurus probably adopted a similar stance at some point, but the museum’s choice of pose nevertheless influences visitors’ understanding of and attitude toward the dinosaur.

Restoring the Classics

With dozens of new Tyrannosaurus mounts springing up across the country and around the world, the original AMNH and CMNH displays began to look increasingly obsolete. Unfortunately, modernizing historic fossil mounts is an extremely complex and expensive process. The early 20th century technicians that built these displays generally intended for them to be permanent: bolts were drilled directly into the bones and gaps were sealed with plaster that can only be removed by manually chipping it away. What’s more, the cumulative effects of rusting armatures, fluctuating humidity, and vibration from passing crowds have considerably damaged historic mounts over the course of their decades on display.

AMNH 5027 was restored and remounted in 1995.

AMNH 5027 was restored and remounted in 1995. Photo by the author.

Despite these challenges, AMNH and CMNH have both been able to restore and update their classic Tyrannosaurus displays. While fossil mounts used to be built in-house, often by the same people who found and described those fossils, modern mounting projects are typically outsourced to specialist companies. Phil Fraley Productions, an exhibit fabrication company based in the Pittsburgh suburbs, was responsible for both T. rex restorations. At AMNH, Jeanne Kelly spent two years disarticulating and conserving each bone before Phil Fraley’s crew took over to build the new armature. The new mount not only corrected the dinosaur’s posture, but improved visitors’ view of the fossils by removing obstructive vertical supports. Instead, most of the skeleton’s weight is now supported by steel cables hanging from the ceiling.  Each bone is secured to an individual metal bracket, allowing researchers to easily remove elements for study as necessary. A new cast of the skull was also prepared, this time with open fenestrae for a more natural appearance. Rather than attempting to match the dramatic and showy T. rex mounts at other museums, the AMNH team chose a comparatively subdued stalking pose. A closed mouth and subtly raised left foot convey a quiet dignity befitting this historically significant display.

Historically, the 1941 CMNH Tyrannosaurus had never quite lived up to its New York predecessor. Although it incorporated the Tyrannosaurus type specimen, it was mostly composed of casts from the New York skeleton, and it sported an unfortunately crude replica skull. It is therefore ironic that CMNH now exhibits the more spectacular T. rex display, one which finally realizes Osborn’s ambitious plan to construct an epic confrontation between two of the giant predators. As they had with the AMNH mount, Phil Fraley’s team dismantled the original display and painstakingly removed many layers of paint, shellac, and plaster from the bones. Michael Holland contributed a new restored skull, actually a composite of several Tyrannosaurus skulls. The restored holotype T. rex now faces off with a cast of “Peck’s Rex”, a specimen recovered from Montana in 1997. Despite the difficulty of modernizing the historic specimen, the team reportedly developed a healthy respect for turn of the century mount-makers like Adam Hermann and Arthur Coggeshall, who developed the techniques for making enduring displays of fragile fossils that are still being refined today.

Continue to Displaying the Tyrant King Part 3.

References

Colbert, E.H., Gillette, D.D. and Molnar, R.N. “North American Dinosaur Hunters.” The Complete Dinosaur, Second Edition. Brett-Surman, M.K., Holtz, T.R. and Farlow, J.O., eds.Bloomington, IN: Indiana University Press.

Dingus, L. 1996. Next of Kin: Great Fossils at the American Museum of Natural History. New York, NY: Rizzoli International Publications, Inc.

Johnson, K. and Stucky, R.K. 2013. “Paleontology: Discovering the Ancient History of the American West.” Denver Museum of Nature and Science Annals, No. 4.

Larson, N. 2008. “One Hundred Years of Tyrannosaurus rex: The Skeletons.” Tyrannosaurus rex, The Tyrant King. Larson, Peter and Carpenter, Kenneth, eds. Bloomington, IN: Indiana University Press.

Naish, D. 2009. The Great Dinosaur Discoveries. Berkeley, CA: University of California Press.

Norell, M., Gaffney, E.S. and Dingus, L. 1995. Discovering Dinosaurs: Evolution, Extinction, and the Lessons of Prehistory.  Berkeley, CA: University of California Press.

Psihoyos, L. 1994. Hunting Dinosaurs. New York, NY: Random House, Inc.

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Filed under AMNH, CMNH, dinosaurs, fossil mounts, history of science, museums, NMNH, paleoart, reptiles, theropods

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April 2, 2014 · 9:44 am

Displaying the Tyrant King – Part 1

 

The original Tyrannosaurus rex mount at the American Museum of Natural History. Photo from Dingus 1996.

The original Tyrannosaurus rex mount at the American Museum of Natural History. Photo from Dingus 1996.

Woodrow Wilson is in the white house. The first World War is raging in Europe, but the United States is not yet involved. The women’s suffrage movement is picking up speed. And you just heard that the skeleton of an actual dragon is on display at the American Museum of Natural History in New York. It is difficult to imagine a time before every man, woman, and child in the developed world knew the name Tyrannosaurus rex, but that world existed not even a century ago. In 1915, AMNH unveiled the very first mounted skeleton of the tyrant lizard king, immediately and irrevocably cementing the image of the towering reptilian carnivore in the popular psyche.

Today, Tyrannosaurus is a celebrity among dinosaurs, appearing in every form of media imaginable. More importantly, however, it is an icon for paleontology and an ambassador to science. The cult of T. rex began in the halls of museums, and museums remain the prehistoric carnivore’s symbolic home. The mounted skeletons in museums provide the legendary T. rex its credibility: these are the authentic remains of the giant predator that once stalked North America. And yet, most of the dozens of  Tyrannosaurus skeletons on display around the world are casts, and none of them represent complete skeletons (rather, they are filled in with spare parts from other specimens and the occasional sculpted bone). These are sculptures as well as scientific specimens, works of installation art composed by artists, engineers, and scientists. Herein lies the paradox presented by all fossil mounts: they are natural specimens and constructed objects, embodying a challenging duality between the realms of empiricism and imagination.

A Tyrannosaurus mount is at once educational and spectacular. Both roles were embraced at AMNH in 1915, and these dual identities have defined T. rex displays ever since. 14 years ago, FMNH PR 2081, also known as Sue, became a star attraction for the Field Museum of Natural History and the city of Chicago at large. Later this month, another T. rex will unwittingly take on a similar role: on April 15th, MOR 555, an 80% complete Tyrannosaurus specimen discovered in Montana, will be dubbed “The Nation’s T. rex“ and entered into the Smithsonian National Museum of Natural History collection with considerable fanfare.

Skull cast of MOR 555, soon to be "The Nation's T. rex", at NMNH.

Skull cast of MOR 555, soon to be “The Nation’s T. rex“, at the National Museum of Natural History. Photo by the author.

This three part series is a look back at how the tyrant king has defined, and been defined by, the museum experience. Part 1 will cover the circumstances surrounding the creation of the iconic original Tyrannosaurus mount in New York, as well as its successor in Pittsburgh. Part 2 will explore the changing role of Tyrannosaurus in museums caused by a surge of new fossil finds and a revolution in our understanding of dinosaurs. Finally, Part 3 will conclude with a discussion of the positives and negatives of a modern world saturated in all things T. rex.

The Original Tyrant

Between 1890 and 1910, the United States’ large urban natural history museums entered into a frenzied competition to find and display the largest and most spectacular dinosaur skeletons. Although the efforts of paleontologists O.C. Marsh and E.D. Cope in the late 19th century fleshed out the scientific understanding of Mesozoic reptiles, it was these turn-of-the-century museum displays that brought dinosaurs into the public sphere. Bankrolled by New York’s wealthy aristocrats and led by the ambitious mega-tool Henry Osborn, AMNH won the fossil race by most any measure. The New York museum completed the world’s first mounted skeleton of a sauropod dinosaur in 1905, and also left its Chicago and Pittsburgh competitors in the dust with the highest visitation rate and the most fossil mounts on display.

Osborn’s goal was to establish AMNH as the global epicenter for paleontology research and education, and in 1905 he revealed his ace in the hole: two partial skeletons of giant meat-eating dinosaurs uncovered by fossil hunter Barnum Brown. In a deceptively brief paper in the Bulletin of the American Museum of Natural History, Osborn described the fossils from Wyoming and Montana, coining the names Dynamosaurus imperiosus and Tyrannosaurus rex (a follow-up paper in 1906 reclassified “Dynamosaurus” as a second Tyrannosaurus specimen). Fully aware of what a unique prize he had in his possession, Osborn wasted no time leveraging the fossils for academic glory (and additional funding from benefactors). He placed the unarticulated Tyrannosaurus fossils on display at AMNH shortly after his initial publication, and commissioned legendary artist Charles Knight to prepare a painting of the animal’s life appearance.

In 1908, Brown collected a much more complete Tyrannosaurus specimen (AMNH 5027), with over 50% of the skeleton intact, including the first complete skull and a significant portion of the torso. With this specimen in hand, AMNH technician Adam Hermann and his team began work on a mounted Tyrannosaurus skeleton to join the Museum’s growing menagerie of mounted dinosaurs and prehistoric mammals. Inspired by the Museum’s collection of taxidermy mounts in dynamic habitat dioramas, and seeking to accentuate the spectacle of his reptilian monster, Osborn initially wanted to mount two Tyrannosaurus skeletons facing off over a dead hadrosaur. He even published a brief description complete with illustrations of the projected scene (shown below). However, the structural limitations inherent to securing heavy fossils to a steel armature, as well as the inadequate amount of Tyrannosaurus fossils available, made such a sensational display impossible to achieve.

Model of unrealized T. rex showdown mount from Osborn 1913.

Model of unrealized T. rex showdown mount. Image from Osborn 1913.

Instead, Hermann prepared a single Tyrannosaurus mount, combining the 1908 specimen with plaster casts of leg bones from the 1905 holotype. The original skull was impractically heavy, so a cast was used in its place. Finally, missing portions of the skeleton, including the arms, feet, and most of the tail, were sculpted by hand using bones from Allosaurus as reference. During the early 20th century, constructing fossil mounts was a relatively new art form, and while Hermann was one of the most talented and prolific mount-makers in the business, his techniques were somewhat unkind to the fossil material. Bolts were drilled directly into the fragile bones to secure them to the armature, and in some cases steel rods were tunneled right through the bones. Any fractures were sealed with plaster, and reconstructed portions were painted to be nearly indistinguishable from the original fossils. Like most of the early AMNH fossil mounts, preserving the integrity of the Tyrannosaurus bones was often secondary to aesthetic concerns like concealing the unsightly armature.

Tyrannosaurus and others in AMNH Dinosaur Hall, 1927. Photo courtesy of AMNH Research Library.

AMNH Tyrannosaurus, ca. 1940. Photo courtesy of the AMNH Research Library.

The completed Tyrannosaurus mount, a magnificent sculptural combination of bone, plaster, and steel, was unveiled in 1915 to stunned audiences. The December 3rd New York Times article was thick with hyperbole, declaring the dinosaur “the prize fighter of antiquity”, “the king of all kings in the domain of animal life,” “the absolute warlord of the earth” and “the most formidable fighting animal of which there is any record whatsoever” (and people say that today’s science journalism is sensationalist!). With its tooth-laden jaws agape and a long, dragging lizard tail extending its length to over 40 feet, the Tyrannosaurus was akin to a mythical dragon, an impossible monster from a primordial world. This dragon, however, was real, albeit safely dead for 66 million years.

Today, we know that the original AMNH Tyrannosaurus mount was inaccurate in many ways. The upright, tail-dragging pose, which had been the most popular attitude for bipedal dinosaurs since Joseph Leidy’s 1868 presentation of Hadrosaurus, is now known to be incorrect. More complete Tyrannosaurus skeletons have revealed that the tail reconstructed by Osborn and Hermann was much too long.  The Allosaurus-inspired sculpted feet were too robust, the legs (casted from the 1905 holotype), were too large compared to the rest of the body, and the hands had too many fingers (the mount was given proper two-fingered hands when it was moved in 1927). It would be misleading to presume that the prehistoric carnivore’s skeleton sprang from the ground exactly as it was presented, but it is equally problematic to reject it as a fake. There are many reasons to criticize Osborn’s leadership at AMNH, but he did not exhibit outright forgeries. The 1915 Tyrannosaurus mount was a solid representation of the best scientific data available at the time, presented in an evocative and compelling manner.

The AMNH Tyrannosaurus mount was no less than an icon: for paleontology, for its host museum, and for the city of New York. The mount has been a New York attraction for longer than the Empire State Building, and for almost 30 years, AMNH was the only place in the world where visitors could see a T. rex in person. In 1918, Tyrannosaurus would make its first Hollywood appearance in the short film The Ghost of Slumber Mountain. This star turn was followed by roles in 1925’s The Lost World and 1933’s King Kong, firmly establishing the tyrant king’s celebrity status. It is noteworthy that special effects artist Willis O’Brian and model maker Marcel Delgado copied the proportions and posture of the AMNH display exactly when creating the dinosaurs for each of these films. The filmmakers apparently took no artistic liberties, recreating Tyrannosaurus precisely how the nation’s top scientists had reconstructed it in the museum.

A T. rex for Pittsburgh

In 1941, AMNH ended it’s Tyrannosaurus monopoly and sold the incomplete type specimen (the partial skeleton described in Osborn’s 1905 publication) to Pittsburgh’s Carnegie Museum of Natural History. While it is sometimes reported that this transfer took place to keep the valuable fossils out of harm’s way during World War II (e.g. Larson 2008), the deal was apparently underway well before the United States became involved in the war. Having paid an astounding $100,000 ($1.7 million in today’s dollars) for the fossils, CMNH staff wasted no time in assembling a mount of their own. The Tyrannosaurus holotype only included only about 15% of the skeleton, so most of Pittsburgh mount had to be made from casts and sculpted elements. Somewhat pointlessly, the skull fragments included with the specimen were buried inside a plaster skull replica, making them inaccessible to researchers for several decades. Completed in less than a year, the CMNH Tyrannosaurus was given an upright, tail-dragging posture very much like its AMNH predecessor.

Carnegie Museum of Natural History. Photo from NPR.

CM 9380 at the Carnegie Museum of Natural History. Source

The mid-20th century is sometimes called the “quiet phase” in vertebrate paleontology. After enjoying public fame and generous federal support during the late 1800s, paleontology as a discipline was largely marginalized when experiment-driven “hard” sciences like physics and molecular biology rose to prominence. By the 1950s and 60s, the comparably small number of researchers studying ancient life were chiefly concerned with theoretical models for quantifying trends in evolution. Although the aging dinosaur displays at American museums remained popular with the public, these animals were perceived as evolutionary dead-ends, of little interest to the majority of scientists. Between 1908 (when Brown found the iconic AMNH Tyrannosaurus skeleton) and 1980, only four largely incomplete Tyrannosaurus specimens were found, and no new mounts of this species were built.

Continue to Displaying the Tyrant King Part 2.

References

Dingus, L. (1996). Next of Kin: Great Fossils at the American Museum of Natural History. New York, NY: Rizzoli International Publications, Inc.

Glut, D. 2008. “Tyrannosaurus rex: A century of celebrity.” Tyrannosaurus rex, The Tyrant King. Larson, Peter and Carpenter, Kenneth, eds. Bloomington, IN: Indiana University Press.

Hermann, A. 1909. “Modern Laboratory Methods in Vertebrate Paleontology.” Bulletin of the American Museum of Natural History 21:283-331.

Larson, N. 2008. “One Hundred Years of Tyrannosaurus rex: The Skeletons.” Tyrannosaurus rex, The Tyrant King. Larson, Peter and Carpenter, Kenneth, eds. Bloomington, IN: Indiana University Press.

“Mining for Mammoths in the Badlands: How Tyrannosaurus Rex Was Dug Out of His 8,000,000 Year old Tomb,” The New York Times, December 3, 1905, page SM1.

Naish, D. 2009. The Great Dinosaur Discoveries. Berkeley, CA: University of California Press.

Osborn, H.F. 1906. “Tyrannosaurus, Upper Cretaceous Carnivorous Dinosaur.” Bulletin of the American Museum of Natural History 22:281-296.

Osborn, H.F. 1913. “Tyrannosaurus, Restoration and Model of the Skeleton.” Bulletin of the American Museum of Natural History 32:9-92.

Rainger, Ronald 1991. “An Agenda for Antiquity: Henry Fairfield Osborn and Vertebrate Paleontology at the American Museum of Natural History, 1890-1935. Tuscaloosa, Alabama. University of Alabama Press.

Wesihampel, D.B. and White, Nadine M. 2003.The Dinosaur Papers: 1676-1906. Washington, DC: Smithsonian Books.

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Filed under AMNH, CMNH, dinosaurs, fossil mounts, history of science, movies, museums, NMNH, reptiles, theropods

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Image

The Stan Gallery

The first-ever mounted skeleton of Tyrannosaurus rex went on display at the American Museum of Natural History in 1915, and for nearly 30 years, the New York museum was the only place in the world where one could see the world’s most famous dinosaur in person. The situation today could not be more different. More than 50 individual Tyrannosaurus specimens of varying degrees of completeness are now known, and thanks to casting technology the number of Tyrannosaurus skeletons on display may well exceed one hundred.

A significant fraction of those displays are casts of BHI 3033, the T. rex specimen more commonly known as Stan. Excavated in South Dakota in 1992 by the Black Hills Institute (a for-profit outfit specializing in excavating, preparing and mounting fossils), Stan is significant for being over two-thirds complete and for including the best preserved Tyrannosaurus skull yet found. Since 1996, BHI has sold dozens of casts of the complete Stan skeleton (missing bones are filled in with casts from the original AMNH T. rex, among others) to museums and other venues around the world. At a relatively affordable $100,000 plus shipping, even small local museums and the occasional wealthy individual can now own a Tyrannosaurus mount. Stan is, by a wide margin, the most duplicated and most exhibited dinosaur in the world today. As of 2008, BHI had sold more than 30 Stan casts, and that number has grown substantially since then, particularly with the increased interest in dinosaur displays in Asia.

One might argue that this extreme amount of replication lessens the cultural value of museum displays. What allure do museums have when the specimens on display are fiberglass replicas, of which identical versions can be seen at dozens of other venues, including corporate offices and amusement parks? I would counter that this is a small price to pay when we consider the immense educational benefits of this unprecedented availability of dinosaur skeletons. Children and adults around the world now have  the opportunity to see a T. rex in person, an experience that was until recently limited to citizens of a handful of large cities. What’s more, the huge body of research on Tyrannosaurus makes it a veritable model organism for vertebrate paleontology, so increasing access to T. rex fossils for international scientists is definitely helpful.

Besides, a fossil mount is far more than the fossil bones it is composed of. Mounts are in equal measures natural specimens and man-made objects, works of installation art designed to communicate a story through pose, posture and a carefully arranged mise-en-scene. Below are 14 examples of Stan on display, highlighting the great range attainable with a single dinosaur.

Image sources: Orientation UofM, a_leistra, Bill and Sandra Wayne, Reluctant Drifter, Roadschooling America, dinonikes, Texas Tigers, Momotarou2012, Helana Handbasket and Marie Thomas.

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February 2, 2014 · 11:55 am
December 26, 2013 · 10:11 pm

Review: Ultimate Dinosaurs at the Cincinnati Museum Center

Ultimate Dinosaurs: Giants from Gondwana premiered in June 2012 with considerable fanfare at the Royal Ontario Museum (ROM) in Toronto. Developed by a ROM team led by David Evans and Matthew Vavrek, Ultimate Dinosaurs showcased the dinosaurs of the southern hemisphere, demonstrating how geographic isolation created Mesozoic ecosystems remarkably different from the menageries we are used to seeing in North American museum displays. The exhibit included 20 dinosaur mounts in all, including many taxa never before seen in museums above the equator.

I never made it to the inaugural showing of Ultimate Dinosaurs, but fortunately the show is now on the road. I saw it at the Cincinnati Museum Center (CMC) earlier this week, where it will remain through January 5th before moving on to Minneapolis. The exhibit assuredly does not disappoint…read on for many pictures and my musings on the design.

DPP_0001

The first room features Triassic and early Jurassic archosaurs.

Huge banners displayed outside the CMC and in the main lobby are impossible to miss, but the Ultimate Dinosaurs exhibit itself is hidden away on the lower level, with the entrance at the end of a quiet corridor. Aside from a video screen showing a shifting map of Gondwana, no proper introduction is provided. Visitors immediately find themselves in the first large room of fossil mounts, featuring Triassic and early Jurassic archosaurs like Herrerasaurus, Eoraptor, Cryolophosaurus and the rauisuchian Prestosuchus. This first batch of mounts is lined up on an elevated platform that runs along the right side of the room. Like all the mounts in Ultimate Dinosaurs, these are casts, and are plainly assembled in “chunks”: numerous bone elements casted together as single pieces. While these shortcuts are obvious up close, this mode of construction does allow for remarkably dynamic poses, and there is no obstructive armature to block one’s view. Behind the dinosaurs is the first of several gorgeous Julius Csotonyi murals, a lively panorama of life reconstructions in a naturalistic setting.

In front of every mount is an array of attractive signs in bright, solid colors. Information is mostly provided in short sound bites or bullet points, highlighting sensible information like the animal’s diet, the meaning of its name, where it was discovered, and why it is scientifically noteworthy. There is also at least one touchscreen in front of each mount, which includes several more pages of information for the more dedicated visitor. I really liked the similar touchscreen displays at the Carnegie Museum, and these are equally impressive. This is technology used intelligently, contributing to but not overwhelming the primary display, while using space in an economical way. I was also impressed by the succinctness of the text. It is very difficult to condense information into short blurbs that visitors can absorb with no more than a quick glance, but the Ultimate Dinosaurs writers balanced accuracy, intrigue and brevity on every single sign. Hats off to them!

Visitors were having a hell of a time pronouncing Cryolophosaurus.

Visitors were having a hell of a time pronouncing Cryolophosaurus.

Turning left at the Massospondylus at the far end of the first room, visitors enter a long and largely empty corridor. The left wall is adorned with a series of signs explaining the historical discovery of and evidence for continental drift, and herein lies my primary concern with the exhibit as a whole. The story being told in Ultimate Dinosaurs, regarding plate tectonics and its effect on evolution, is an important one. Paleobiogeography is key to understanding how the natural world we know today came to be. What’s more, it’s a great example of science in action, consisting of a handful of intuitive, evidence-based concepts that can be applied to new situations and clarify new discoveries.  As such, paleobiogeography ought to frame the entire exhibit. I would have placed the big ideas and central questions (Why are similar organisms sometimes found on opposite sides of oceans? What happens when populations or ecosystems are isolated from one another?) at the beginning, and ensured that they were reinforced in every display with recurring terms, imagery and motifs. The paleobiogeography story should guide the visitor’s experience and understanding of the exhibit.

Instead, Ultimate Dinosaurs at the CMC relegates the big ideas to secluded corners and easily-missed signs. The text itself is very clear and well-written, and supported by attractive, intuitive graphics, but it’s hidden away and or otherwise overshadowed by lists of factoids about each dinosaur. My largely unsubstantiated suspicion is that the original designers of Ultimate Dinosaurs at the ROM intended for the paleobiogeography story to be much more explicit, but this vision was compromised somewhat in order to fit the exhibit into the space available at the CMC. The unfortunate result is that the most critical information is introduced in an unorganized manner, and the exhibit is weaker for it.

Suchomimus peers in from the right, Amargasaurus and

Suchomimus peers in from the right, Malawisaurus in the middle, Argentina in back.

After passing through the switchbacking corridor, visitors reach the primary showroom. This is an enormous space filled with huge, impressive dinosaur mounts. Like the rest of the exhibit, this gallery is quite dark, with floor lights and the occasional overhead light highlighting the dinosaurs. The darkness helps to hide the unadorned walls and ceilings of the multipurpose space being used, but thankfully does not hinder one’s view of the dinosaurs. And the dinosaurs certainly do not disappoint. Even though they are casts, this exhibit was my first opportunity to see the likes of Armagasaurus, Suchomimus, Ouranosaurus and many others in person. I could walk around them, take in their scale and compare them to one another and to myself, experiences that no image or documentary can provide.

Majungasaurus and Rapetosaurus strike an extreme pose.

Majungasaurus and Rapetosaurus strike an extreme pose.

Most of the dinosaurs are in lively poses, as though the animal was frozen midstride, but a few are especially dynamic. Little Rahonavis is suspended from the ceiling, as though leaping for prey or perhaps engaging in a controlled glide to the forest floor. The Majungasaurus and Rapetosaurus, which are the only mounts directly interacting with one another, are particularly interesting. The attacking Majungasaurus has its foot up on the flank of the Rapetosaurus, and the sauropod is in a rather unusual squatting pose, with its forelimbs at what appears to be maximum flexion. I will leave it to the experts to decide whether this extreme pose is plausible, but this nevertheless serves as a reminder of what can be learned by assembling a skeleton in three-dimensional space.

Carnotaurus

Carnotaurus and Amargasaurus.

The mounts are clustered on three islands, representing Argentina, Madagascar and Niger. I do wish this organization had been made clearer to visitors, perhaps with large banners over the islands naming the dinosaurs’ location of origin. Clustered at the feet of the mounts are small cases containing a mix of original and casted fossils. Some of those are quite relevant and provide further context to the mounts: for instance, a collection of North African fossil fish near the Suchomimus illustrate the spinosaur’s probable diet. Other cases are a bit more perplexing. A series of cervical vertebrae from the North American sauropod Suuwassea is arbitrarily situated among the Madagascar mounts, and cases of cephalopods and Carboniferous plants are similarly out of place. Most of these oddball fossil displays did not come from the ROM, but were added by the CMC from their own collections. Although these fossils are fascinating and should absolutely be on display, I don’t think randomly interjecting them among the Gondwanan dinosaurs was the way to go. These displays interrupt the primary storyline and probably should have been placed elsewhere.

CWC addition

These additions from the CMC are neat, but a bit out of place.

The final room showcases the exhibit’s two largest mounts, Tyrannosaurus and Giganotosaurus. It is undeniably exciting to see these two giant predators side by side, and compare how these ostensibly similar carnivores were nevertheless subtly adapted to tackle different prey. I would have made this point more obvious than the exhibit does, but I suppose sometimes you need to step back and let your specimens speak for themselves.

This room also features the much-ballyhooed “augmented reality” gimmick. These are tablet-sized screens found alongside the mounts. When you point these at the Tyrannosaurus and Giganotosaurus skeletons, a CG version of dinosaur appears on the screen. Panning and tilting the tablet in front of the mount causes your view of the CG version to adjust accordingly. I found these sort of interesting, but they were not nearly as impressive as the mounts themselves. Unfortunately, the CG dinosaurs simply didn’t look very good. I am all for the use of technology in museum exhibits, but only if it plays to our strengths. In this case, the CG dinosaurs are directly and unfavorably comparable to a wide range of films and television shows that people can see without leaving home. As hubs for lifetime learning, museums can and should offer more than that.

Tyrannosaurus and Giganotosaurus side by side. Eat it up, internet.

Tyrannosaurus and Giganotosaurus side by side. Eat it up, internet.

Despite my nitpicks, Ultimate Dinosaurs really does live up to its name. This is a very handsomely designed exhibit, and an great opportunity to see mounts of exotic dinosaur taxa. If you are at all interested in paleontology, catching this exhibit is a no-brainer. But even if you’re not, this is a rare chance to see what the vertebrate fossil record has to offer beyond T. rex and Triceratops, and learn a bit about how our world came to be.

Edit: I had mistakenly said the murals were created by Raul Martin. They are the work of Julius Csotonyi.

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September 23, 2012 · 9:10 am

Extinct Monsters: The Marsh Dinosaurs, Part II

Read the Marsh Dinosaurs, Part I or start the Extinct Monsters series from the beginning.

During the first decade of the 20th century, the United States National Museum paleontology department was located in an offsite building in northwest Washington, DC. It was here that preparators Charles Gilmore, Norman Boss, and James Gidley slowly but surely worked through the literal trainloads of fossil specimens O.C. Marsh had acquired for the United States Geological Survey. The Marsh Collection included unknown thousands of specimens, many of them holotypes, and there was no shortage of gorgeous display-caliber material. Even after the “condemnation of worthless material” Gilmore and his team quickly filled the available exhibit space in the Arts and Industries Building with mounted skeletons.

The Ceratosaurus

With no more display space and plenty more fossils, it was fortunate that the USNM moved to a new, larger building in 1910. In this iconic, green-domed building (now the National Museum of Natural History), the paleontology department received newly furnished collections spaces and the entire east wing to fill with display specimens. The evocatively titled Hall of Extinct Monsters provided a new home for the mounted skeletons already constructed for the old exhibit, as well as plenty of room for new displays.

The Ceratosaurus nasicornis holotype was originally housed in a glass case. Image courtesy of the Linda Hall Library.

Ceratosaurus. Photo by the author.

The delicate arms of Ceratosaurus were removed several years prior to the hall’s closing. Photo by the author.

One of the first new additions was the type specimen of Ceratosaurus nasicornis (USNM 4735), mounted in relief. Marshall Felch led the excavation of this specimen in 1883 at a quarry near Cañon City, Colorado. The nearly complete skeleton received a cursory description from Marsh upon its discovery, but it was Gilmore who described it properly in 1920, ten years after it was put on display. When it was introduced to the Hall of Extinct Monsters, this was the only Ceratosaurus specimen yet found, making the mount a USNM exclusive. The skeleton was originally displayed in a glass case, but during the 1963 renovation it was placed in a more open setting.

Even today, Ceratosaurus is only known from a handful of specimens. For this reason, the original Ceratosaurus fossils will not be returning when the current renovation is completed in 2019. The new hall will instead feature a three-dimensional, standing cast of this skeleton. The original fossils are now in the museum’s collections, available for proper study for the first time in over a century.

The Camptosaurus

In 1912, two mounted skeletons of Camptosaurus, one large (USNM 4282) and one small (USNM 2210), were introduced to the Hall of Extinct Monsters. William Read excavated both specimens at Quarry 13 in the Como region of Wyoming a quarter of a century earlier. Representing the first-ever mounted skeletons of Camptosaurus, these specimens have had a rather complex taxonomical history. Marsh initially described both specimens as Camptosaurus nanus, a new species within the genus Camptosaurus (the type species was Camptosaurus dispar, also coined by Marsh). After the fossils were acquired by the USNM, Gilmore re-described the larger individual as a new species, Camptosaurus browni. This designation remained until the 1980s, when Peter Galton and H.P. Powell determined that C. nanus and C. browni were actually both growth stages of C. dispar.

Regardless of what they are called, both specimens were remarkably well-preserved and reasonably complete. Most of the skeletal elements of the larger Camptosaurus came from a single individual that was found articulated in situ. However, some of the cervical vertebrae came from another specimen from the same quarry, and the skull, pubis, and some of the ribs were reconstructed. Of particular interest is the right ilium, which has been punctured all the way through by a force delivered from above. Gilmore postulated that “the position of the wounds suggest…that this individual was a female who might have received the injuries during copulation.” The smaller “C. nanus” was also found mostly complete, but two metatarsals came from a different individual and the skull and left forelimb were sculpted.

The original pair of Camptosaurus mounts. Image from Backyard Dinosaurs.

Gilmore supervised the creation of both mounts, and constructed the larger individual himself. Norman Boss took the lead on the smaller specimen. As with the other dinosaur skeletons, the mount was centered on an inch-thick steel rod bent to conform to the shape of the vertebral column. Bolts were drilled directly into the vertebrae to attach them to the armature, and the vertebral foramina were filled with liberal amounts of plaster to secure them to the rod. A similar process was used to assemble each of the limbs, and the ribs were supported by a wire cage.

Gilmore aimed to correct many specifics of Marsh’s  original illustrated reconstruction of Camptosaurus. To start, he shortened the presacral region to make a more compact torso. Marsh had also inexplicably illustrated Camptosaurus with lumbar vertebrae (a characteristic exclusive to mammals), which Gilmore corrected. Finally, Marsh had reconstructed the animal as an obligate biped, but Gilmore  determined that “Camptosaurus used the quadrupedal mode of progression more frequently than any other known member of Ornithopoda.” Accordingly, the larger Camptosaurus mount was posed on all fours. The completed Camptosaurus mounts were placed together in a freestanding glass case toward the rear of the Hall of Extinct Monsters. In 1962 the pair was moved to the left of the Diplodocus on the central pedestal of the redesigned exhibit. During the 1981 renovation they were moved a few feet back, so that they were alongside the sauropod’s tail.

This cast replaced the original Camptosaurus mount in 2010. Photo by the author.

This cast replaced the original Camptosaurus mounts in 2010. Photo by the author.

The retired plaster skulls of the original Camptosaurus mounts. Photo by the author.

The retired plaster skulls of the original Camptosaurus mounts. Photo by the author.

Both Camptosaurus skeletons taken off exhibit in 2010 and replaced with a cast of the adult. The delicate fossils, which had suffered from considerable wear and tear over the past hundred years, were stabilized and stored individually for their protection. The new mount has a number of upgrades to reflect our improved understanding of dinosaur anatomy. The arms are closer together and the palms face inward, because the pronated (palms down) hands on Gilmore’s version have been determined to be a physical impossibility. The new mount also features a completely different skull. The rectangular model skull used on the original mount was based on Iguanodon, but new discoveries show that the skull of Camptosaurus was more triangular in shape. Both the adult and juvenile Camptosaurus will appear in the new National Fossil Hall.

The Stegosaurus

The Smithsonian’s first Stegosaurus exhibit was a life-sized model built for the 1904 World’s Fair in St. Louis. This model found its way into the Hall of Extinct Monsters in 1910. In 1913, the model was joined by a mounted Stegosaurus skeleton found at the same Cañon City quarry as the Ceratosaurus. A third Stegosaurus, the holotype of S. stenops, was introduced in 1918. Lovingly called the “roadkill” Stegosaurus, USNM 4934 is remarkable in part because it was found completely articulated. In fact, before its 1886 discovery by Marshall Felch, it was unknown exactly how the animal’s plates were positioned on its back.

Standing Stegosaurus mount and life-size model, circa 1950. Photo courtesy of the Smithsonian Institution Archives.

Stegosaurus

Stegosaurus model, standing mount, and “roadkill” on display in the Hall of Extinct Monsters. Source

All three Stegosaurus displays were moved in 1963 and 1981. In Fossils: The History of Life, the Stegosaurus skeletons were positioned flanking the Diplodocus in the central display area, with the standing mount on the right and the roadkill skeleton on the left. The model Stegosaurus stood opposite the mount. Just like the Triceratops and Camptosaurus, many decades on display took their toll on the standing Stegosaurus, so in 2003 the fossils were removed from the exhibit. Dismantling the Stegosaurus was particularly challenging because of the large amount of plaster applied by the mount’s creators. In some cases the plaster infill had to be removed with hand tools, which put further pressure on the fossils. Additionally, the rod supporting the backbone had been threaded right through each of the vertebrae, and was extremely difficult to remove. A casted Stegosaurus mount in a more active pose was returned to the exhibit in 2004.

Cast of Stegosaurus and Camptosaurus. Photo by the author.

Casts of Stegosaurus and Camptosaurus. Photo by the author.

Roadkill stego

“Roadkill” Stegosaurus in 2014. Photo by the author.

After 110 years on display at the Smithsonian, the model Stegosaurus has been donated to the Museum of the Earth in Ithaca. The roadkill Stegosaurus, however, will feature prominently in the new National Fossil Hall, mounted upright on the wall by the exhibit’s secondary entrance. The 2004 Stegosaurus cast had a number of anatomical issues and will not be returning – instead, it will be replaced by an updated cast made from the same original fossils.

The Marsh dinosaurs have been of critical importance in our understanding of the Mesozoic world, but at this point these fossils are historic artifacts as well. When they were uncovered, the American civil war was still a recent memory, and railroads had only recently extended to the western United States. Before the first world war they had been assembled into mounts, and for more than a century these fossils have been mesmerizing and inspiring millions of visitors. Several of these mounts, including the Triceratops, Ceratosaurus and Camptosaurus, were the first reconstructions of these species to ever appear in the public realm, and therefore defined popular interpretations that have lasted for generations. Some visitors may lament that many of the original specimens have been recently been replaced with replicas, but the fact is that these are irreplaceable and invaluable national treasures. They inform us of our culture, and our dedication to expanding knowledge and our rich natural history. We only get one chance with these fossils, and that is why the absolute best care must be taken to preserve them for future generations.

References

Gilmore, C.W. 1912 “The Mounted Skeletons of Camptosaurus in the United States National Musuem.” Proceedings of the US National Museum 14:1878.

Gilmore, C.W. 1941 “A History of the Division of Vertebrate Paleontology in the United States National Museum.” Proceedings of the United States National Museum 90.

Jabo, S. 2012. Personal communication.

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Aside

Medullary Bone and the Dinosaur-Bird Link

One of the coolest lines of evidence that birds are extant dinosaurs is the presence of medullary bone in multiple dinosaur species. Medullary bone (hereafter referred to as MB, to avoid confusion with the medullary surface) is a temporary tissue that forms on the interior surfaces of the long bones of birds. MB is identified by unique collagen organization: it is both densely mineralized and strongly vascularized. This structure helps MB serve its purpose as a readily retrieved source of calcium for use in forming eggshells, and prevents incapacitating bone resorption during this process. Among extant animals, MB is only found in mature female birds in the process of producing eggs. Its creation is triggered by hormones during the onset of ovulation, and it disappears during the laying process. Among extant animals, MB is only known in birds. However, in 2005 Mary Schweitzer and colleagues reported their discovery of medullary bone in a Tyrannosaurus rex individual. Lee and Werning followed up on this research in 2007 by reporting MB in the theropod Allosaurus and the ornithopod Tenontosaurus.

Medullary bone in modern Gallus and fossil Tyrannosaurus. From http://www.abc.net.au/science.

Since MB is unique to reproductively active females, most popular coverage of dinosaur MB  has focused on its potential use for determining the sex and life stage of individual dinosaur specimens. We shouldn’t, however, lose sight of the fact that MB is an independent line of evidence supporting a close phylogenetic relationship between dinosaurs and birds. Nearly all paleontologists agree that the evidence that birds are dinosaurs is overwhelming, and MB is but a drop in the ocean of shared characters between birds and dinosaurs. Nevertheless, it is noteworthy that few authors have attempted to challenge Schweitzer’s initial publication.

The only work I have found  that disputes Schweitzer and colleagues is the dissertation of Dr. Devon Quick  (.pdf link), in which Dr. Quick and Dr. John Ruben investigated the reliability of the methods used to recognize MB in the fossil record using extant animals. This is not, incidentally, the only work by Quick and Ruben challenging the dinosaur-bird connection. As a doe-eyed student, I’d like to take a shot at reviewing this paper. And since I’m posting it publicly, I of course welcome anyone who’d be so kind as to call me out for being wrong.

Quick and Ruben looked at cross-sections of the femora and tibiotarsi of a crocodilian (Alligator mississippiensis) and several birds. Scanning electron microscopy revealed that the medullary surfaces of the tibiotarsi of  reproductively active birds displayed the highly contoured and floccular texture that is characteristic of MB. Likewise, the male and non-reproductively active female birds displayed smooth medullary surfaces. In this regard, Quick and Ruben are in agreement with previous work. However, the authors also reported that the medullary cavity of the alligator femur contained “material superficially similar to…avian medullary bone” (Quick and Ruben 2008). This material was limited to the immediate diaphyseal side of the metaphysis, making it much less extensive than what was observed in birds. Since the alligator individual used in the study was a juvenile male, it was almost certainly not producing reproductively-specific MB. From this observation, the authors conclude from these data that a floccular texture may indicate early-stage bone mineralization and is not a reliable indicator of MB.

Quick and Ruben’s results are unconvincing in part due to a weak experimental design. Their conclusions are dependent on observations gleaned from a single alligator specimen, which is not an adequate sample. The authors’ conclusions would carry more weight if they had looked at multiple individuals. It would also be beneficial to compare males, females, adults and juveniles. Ideally, additionally crocodilian species ought to be included in the study, as well. Schweitzer and colleagues carried out a similar investigation, in which they looked for evidence of MB in multiple alligators, including gravid females, males and juveniles (Schweitzer et al. 2007). Schweitzer and colleagues found no evidence of MB, even with estrogen stimulation, and their larger sample size allows their study to carry more weight than that of Quick and Ruben. Furthermore, although Quick and Ruben assert that that “histological aspects of Tyrannosaurus tissues that are supposedly consistent with an avian-style reproductive physiology were not analyzed carefully”, they did not look at the Tyrannosaurus material as part of their study. Accordingly, no evidence is provided that the structures the authors observed on their alligator were synonymous with those observed by Schweitzer and colleagues on Tyrannosaurus. Finally, Quick and Ruben’s observations are focused on the floccular texture used to identify MB, when in fact Schweitzer and colleagues used several other indicators, including extensive vascularization, to identify MB in Tyrannosaurus. It is notable that the structure, thickness and texture of MB in modern birds varies considerably based on the specifics of the animal’s reproductive biology and the size of the taxa. Given that Tyrannosaurus is several orders of magnitude larger than most extant birds, some structural difference is to be expected (wow, that sentence had some serious science snark).

Quick and Ruben suggest that the floccular texture on the alligator bone may be the result of early-stage mineralization, which would be consistent with the sub-adult status of the individual they used in the study. The authors go on to speculate that a similar explanation might account for the evidence of MB in Tyrannosaurus. Again, it would have been helpful if the authors had amassed more examples of sub-adult archosaurs undergoing skeletal mineralization, and compared them directly to the Tyrannosaurus material in question, rather than merely speculating. If the Tyrannosaurus was forming MB, this would be consistent with information from lines of arrested growth in Tyrannosaurus and other dinosaurs, which indicates that dinosaurs became reproductively active before reaching adult size.

Having reached the somewhat tenuous conclusion that texture is not a reliable indicator of MB, Quick and Ruben go on to argue that even if MB is present in dinosaurs, the fact that it has been reported in both saurischians and ornithiscians “offers no particular insight into the phylogenetic origins of birds.” On the contrary, MB is an independently observable feature that unites the crown group Dinosauria with Avialae, and therefore supports the consensus that Avialae is bracketed by Dinosauria. At the very least, MB suggests marked similarity in reproductive strategies employed by birds and dinosaurs. As demonstrated by Schweitzer and colleagues, MB is not known in crocodilians. Quick and Ruben freely admit this, which makes their statement that MB “may well be a plesiomorphic trait that first evolved in basal archosaurs” nonsensical (Quick and Ruben 2008). The authors could theoretically argue that MB production is primitive but was lost in modern crocodilians, but there is no evidence for this.

Overall, Quick and Ruben’s work is hindered by weak experimental design and vague, unsupported conclusions. Given that a similar but more rigorous study regarding MB in crocodilians has already been carried out by Schweitzer and colleagues, Quick and Ruben’s interpretations are not convincing. Even the broadest interpretation of the available evidence indicates that MB originated after the divergence of crocodilymorphs from the main archosaur line. The phylogeny postulated by Schweitzer and colleagues remains most tenable, in which MB originated in early dinosaurs, and was inherited by ornithiscians, tyrannosaurids and modern birds (Schweitzer et al. 2005).

References

Lee, A. H. and Werning, S. “Sexual maturity in growing dinosaurs does not fit reptilian growth models.” 2007. PNAS 105:2:582-587.

Quick, D. E. and Ruben, J. A. “Amniote bone structure and longbone histology in birds, alligators and the theropod Tyrannosaurus rex.” 2008. Oregon State University.

Schweitzer, M. H., Elsey, R. M., Dacke, C. G., Horner, J. R. and Lamm, E. T. “Do egg-laying crocodilian (Alligator mississippiensis) archosaurs form medullary bone?” 2007. Bone 40: 1152-1158.

Schweitzer, M. H., Wittmeyer, J. L. and Horner, J. R. “Gender-Specific Reproductive Tissue in Ratites and Tyrannosaurus rex.”2005. Science 308: 1456-1460.

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January 20, 2012 · 6:26 am
February 23, 2011 · 11:23 pm

More Fun at the Carnegie Museum

I just have to share this picture, also from the Carnegie Museum of Natural History (see previous post). While the “Dinosaurs in their Time” gallery is fantastic, this has to be one of the worst museum displays I’ve ever seen, as well as one of the most fascinating.

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