Category Archives: theropods

The Field Museum Shuffles its Dinosaurs

Rendering of Patagotitan and the Sue remount. Source

This morning, The Field Museum of Natural History announced two big changes to its dinosaur exhibits. First, the indispensable Sue the Tyrannosaurus will move from its prime location in the central Stanley Field Hall and into Evolving Planet, the museum’s permanent paleontology exhibit. Next, a cast of the South American sauropod Patagotitan will take Sue’s place in the main hall. Sue will be disassembled just a few months from now in February 2018. Patagotitan will be installed later next year, and Sue’s new home on the second floor opens in Spring 2019 (perhaps deliberately, this is within weeks of the National Fossil Hall’s reopening at the Smithsonian).

Sue has been the Field Museum’s defining attraction since the skeleton was acquired in 1997. It is the most complete Tyrannosaurus yet found, but it is also more than a natural history specimen. Sue is part of the pantheon of Chicago landmarks, and the public’s association of the mount with the city it resides in has all but eclipsed the legal battle that preceeded it’s acquisition.

The current Sue mount has a touch of “grenade-swallowing syndrome.” Photo by the author.

Nevertheless, the Sue mount that has been on display for 17 years is not perfect. Assembled by Phil Fraley Productions, the mount has been the subject of grumbling among tyrannosaur specialists for years: the coracoids are too far apart, the furcula is incorrectly placed, the posterior ribs are unnaturally bowed out, and so forth. Happily, Sue will be getting thoroughly updated during the move. In addition to correcting the various anatomical problems, the new mount will reintroduce Sue to its gastralia (belly ribs), which have been displayed separately since 2000, and change her crouching pose to a standing one. As Collections Manager Bill Simpson explains in the announcement video, “we now know more about how a T. rex skeleton should look and Sue is going to reflect those changes.”

Sue 2.0 will take over the second floor space occupied by the recently shuttered 3-D theater. Accessible as an annex to the dinosaur section of Evolving Planet, the Sue exhibit will contextualize the Tyrannosaurus with other fossils from the Hell Creek Formation.

Rendering of Patagotitan in the Stanley Field Hall. Source

Patagotitan is the same animal that the American Museum of Natural History billed as “the titanosaur” two years ago. Argentina’s newest megasauropod was first announced in 2014 but was formally named and published by José Carballido and colleagues just three weeks ago. While not technically the biggest known sauropod, Patagotitan is the only dinosaur in its class known  from reasonably complete remains. The skeleton itself will be more or less identical to the cast Research Casting International produced for AMNH. However, instead of being crammed into a small room, this Patagotitan will have space to stretch out, its neck craning to look over the second story mezzanine. The Field Museum exhibits team also wants visitors to be able to walk under and even touch the cast skeleton.

What do I think about all this (asked nobody)? I’m thrilled with the plans for Sue – it’s great that even though Sue is such an important symbol for the Field Museum, they don’t consider it a static piece. Much credit is due for the museum’s willingness to invest in their star attraction by keeping it up to the latest scientific standard. In addition, I never entirely liked how disassociated Sue was from the rest of the paleontology displays, and it’s nice to know that somebody at the museum must have felt the same way. There’s something to be said for giving the skeleton pride of place, but ultimately I think museumgoers will be better served by seeing Sue contextualized within the story of life on Earth.

While I love me some megasauropods, I can’t help but be less excited by the Patagotitan. I realize that most people don’t go to every natural history museum, but two identical casts already exist. To be fair, the Field Museum Patagotitan will be in a very different setting from its AMNH predecessor (although it may turn out rather like the Royal Ontario Museum Futalognkosaurus). Still, I would rather have seen something more unique to the Field Museum. One idea would be to bring back the Brachiosaurus reconstruction, and display it side-by-side with a remount of the historic Apatosaurus currently in Evolving Planet. Both specimens are tied to the museum’s own expeditionary history, and together would tell the remarkable story of Elmer Riggs. The Apatosaurus in particular could anchor a Field Museum retrospective, while images of the three different locations it has been displayed in since 1908.

The last time a sauropod graced the Stanley Field Hall. Source

Somebody more cynical than me might point out that switching up iconic displays is becoming a predictable way for museums to generate press and manufacture controversy. For example, the Natural History Museum in London got no less than three media splashes when they announced Dippy the Diplodocus was to be replaced, actually removed Dippy, and finally unveiled the remounted blue whale in Hintze Hall earlier this summer. Nevertheless, there is a strong case to be made that stirring up public reactions in this way is an effective way to keep the people interested in their museums. As Field Museum president Richard Lariviere told the Chicago Tribune, “the public doesn’t understand that the science…we convey is changing on an almost hourly basis here. I talk to people all the time who think that since they’ve been to the Field Museum 10 years ago they’ve seen it. By transforming the central space, we hope to convey that exact message.”

At any rate, we’re in for some great new dinosaur displays at the Field Museum over the next couple years. What do you think of the upcoming changes?

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Filed under dinosaurs, exhibits, FMNH, fossil mounts, museums, opinion, sauropods, theropods

Acrocanthosaurus, the Terror of the South

Acrocanthosaurus at the North Carolina Museum of Natural Science. Photo by the author.

Following yesterday’s travelogue about the North Carolina Museum of Natural Science (NCSM), I thought I’d go into a little more depth about the museum’s star fossil. One of only five Acrocanthosaurus specimens ever found, NCSM 14345 is the most complete and the only one on public display. The mounted skeleton has been at the Raleigh museum since 2000. Among other things, its story highlights the challenging relationship between academic paleontologists and the private fossil trade.

Despite its current home in North Carolina, this Acrocanthosaurus hails from the town of Idabel in southeast Oklahoma, more than a thousand miles away. Avocational fossil hunters Cephis Hall and Sid Love (both now deceased) discovered the skeleton in 1983. After making an arrangement with the landowner, the pair spent the next three years carefully excavating the find.

The Acrocanthosaurus was recovered from the early to mid Cretaceous rocks of the Antlers Formation. Found in a deposit of fine sandstone and dark mudstone alongside lots of lignitized wood, the animal’s final resting place was probably a stagnant swamp or pond. Additional evidence for the depositional environment comes from the way the bones are preserved. They contain a great deal of pyrite, and were encrusted with dense concretions of calcium carbonate. Both of these minerals are formed by bacteria blooms in low-oxygen locales, such as the mud at the bottom of a swamp. Gouges in the skull, ribs, and foot indicate scavengers – crocodiles and possibly other Acrocanthosaurus – were feeding on the carcass before it was buried.

All told, the find included a complete skull (the only one of its kind), the pelvis and sacral vertebrae, both arms and shoulder girdles, the right leg, and parts of the rib cage and tail. Paleontologist Richard Cifelli of the Sam Noble Museum in Norman, Oklahoma became aware of the discovery in 1987. Cifelli initially hoped that the museum could acquire the specimen for study and safekeeping, but Hall and Love’s asking price was beyond their means. Instead, Hall and Love loaned the fossils to the University of Texas. They were unsatisfied with this arrangement, however, and drove down to Austin to retrieve their dinosaur (the details of this event are apparently contentious). Hall and Love then sold the fossils to Geological Enterprises, a for-profit outfit based in Ardmore, Oklahoma, for $225,000 plus the promise of a cast once the prep work was completed. Geological Enterprises founder A. Allen Graffham gave the specimen the nickname “Fran,” after his wife.

The meticulously reconstructed Acrocanthosaurus skull. Photo by the author.

The calcium carbonate concretions and heavy pyrite content made the Acrocanthosaurus a particularly challenging fossil to prepare. The concretions are like natural cement and are very difficult to remove without damaging the bones. Meanwhile, pyrite breaks down into sulfur when exposed to oxygen and humidity, which can cause bones to crumble. In 1991, Graffham outsourced the preparation job to the Black Hills Institute in Hill City, South Dakota. Terry Wentz led the preparation project at BHI, which was reportedly one of the most challenging assignments of his career. The concretions encrusting the bones were so dense that they often had to be ground off, rather than chipped. This process could take several hours just to remove a few millimeters of calcium carbonate. To make matters worse, removing pyrite releases acidic particulates into the air. Preparators had to wear respirators and the bones had to be prepared in vacuum boxes.

The most daunting part of the project was reconstructing the specimen’s beautiful and intact skull. Although virtually complete, the skull was found crushed flat. Everyone involved agreed that the skull would be more informative and more impressive if it could be reinflated, but that was easier said then done. Over a year of work went into carefully separating the individual skull bones and reassembling them into their life position.

After five years of what was probably one of the most difficult fossil prep jobs ever attempted, the Acrocanthosaurus was ready to be sold. However, Graffham initially had trouble finding a buyer. There were interested parties in Japan, but he reportedly did not want the fossils to leave the United States.

On October 4, 1997, another well-preserved theropod skeleton went up for auction at Sotheby’s in New York. Sue – the most complete Tyrannosaurus ever found – was already legendary thanks to the protracted legal battle over the fossils. Now that the one-of-a-kind skeleton was being sold at a high profile auction, paleontologists feared that it would disappear into the hands of a private collector. On the night of the auction, most of the museums and other public repositories in the running were outbid within minutes. The North Carolina Museum of Natural Science appeared to be the only museum left after the price topped $5 million, and so the hopes of the paleontological community rested on their shoulders. NCSM dropped out at $7.2 million, and moments later Richard Gray, a veteran of art auctions, won Sue on behalf of a mysterious client. Happily, that client turned out to be the Field Museum (with financial backing from McDonald’s and Disney), and so Sue ended up in a public repository after all.

The Acrocanthosaurus and its sauropod companion can be seen from the ground and from a balcony. Photo by the author.

Still, NCSM had been willing to stake an enormous amount of money on a name brand dinosaur, and they weren’t about to give up. Two months after the Sue auction, the Friends of the North Carolina Museum of Natural Sciences bought the Acrocanthosaurus from Graffham’s company for $3 million. BHI prepared the mount, which debuted along with the rest of the museum’s new building on April 7, 2000. It may not be coincidental that this was just one month before the mounted skeleton of Sue was unveiled in Chicago.

The Acrocanthosaurus occupies a well-lit, circular atrium on the museum’s third floor. Visible both from the ground and from a balcony, the mount is accompanied by a rather goofy-looking sauropod statue. Model pterosaurs circle overhead on a rotating arm, and recreations of theropod and sauropod tracks from Dinosaur State Park in Paluxy, Texas can be seen throughout the room. The original skull is on display in a case outside the atrium.

Sadly, pyrite deterioration has continued to ravage the delicate fossils. Several of the original bones once included in the NCSM mount have been retired to the collections for safekeeping. As of this year, only the arms, right foot, and vertebrae appear to be original material. The rest have been replaced with casts.

Exhibit signs have also changed since the 2000 debut. NCSM exhibits staff learned from surveys that 80% of visitors thought the dinosaur on display was a T. rex, and plenty more assumed the whole skeleton was a replica. In response, most of the signage was redesigned. The displays now highlight the differences between “Acro” and T. rex, and highlight the exceptional rarity of the museum’s Acrocanthosaurus specimen.

A number of NCSM 14345 casts are on display at museums throughout North America, including the Virginia Museum of Natural History, the Houston Museum of Nature and Science, and the Kenosha Public Museum. As promised, Hall and Love were awarded a complete cast of the skeleton,  but without the means to assemble or display it, the replica sat in storage for several years. Eventually, local third and fourth graders successfully raised the $150,000 needed to display the cast at the Museum of the Red River in Idabel.

Acrocanthosaurus cast at the Virginia Museum of Natural History. Photo by the author.

Acrocanthosaurus cast at the Houston Museum of Nature and Science. Photo by the author.

Fossils are precious remains of real organisms, clues about ecosystems from long ago and the making of the world as we know it today. In an ideal world, all significant fossils would, from the moment of their discovery, be accessioned and held in a public collection at a museum or university. A fossil sitting on somebody’s mantelpiece or waiting to be sold at auction is doing nothing to grow our collective knowledge. However, public institutions don’t have the resources to find and excavate every fossil, and in the United States fossils found on private land belong to the landowners. That means that, for better or worse, there is a thriving commercial market for rare fossils.

A plurality of paleontologists do not engage with fossil dealers for ethical reasons. Indeed, even if they wanted to buy rare specimens, academic institutions can seldom match the prices individual collectors are willing to pay. Museums don’t usually have $3 million sitting around. That kind of money could fund a whole research team for years. As such, we’re left with a Catch-22. Paleontologists want important fossils to be in museums where they can be seen and studied by everyone. But if those fossils are in private hands, buying them would support and legitimize the industry that is also keeping fossils out of public collections. If there was an easy solution, it would have been worked out by now.

Nevertheless, serendipity occasionally strikes. This seems to have been the case with the Acrocanthosaurus. News about Sue generated interest in buying a name-brand dinosaur, and donors were willing to put up the money to get the specimen for NCSM. The skeleton is now in a public collection, at a free museum, no less. Meanwhile, the collectors were well compensated for their considerable investment. It’s hard to chalk that up as anything but a win, all around.

References

Carpenter, K. 2016. Acrocanthosaurus Inside and Out. Norman, OK: University of Oklahoma Press.

du Lac, J.F. 2014. The T. rex that got away: Smithsonian’s quest for Sue ends with different dinosaur. The Washington Post

Eddy, D.R. and Clarke, J.A. 2011. New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda). PLoS ONE 6:3:e17932.

Lovelady, W. 2012. Every Step You Take. Exhibits and Emerging Media, North Carolina Museum of Natural Science. 

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Filed under dinosaurs, fossil mounts, museums, reptiles, theropods

The National Fossil Hall Rejects

In April 2014, the paleontology exhibits at the National Museum of Natural History closed for a wall-to-wall renovation. The re-imagined National Fossil Hall will reopen in 2019. We are now approaching the halfway point of this journey, which seems like a fine time to say farewell to some of the more charismatic specimens that are being rotated off display.

In comparison to the old exhibit, the new version will be influenced by a less-is-more design philosophy. While there will not be quite as many individual specimens on display, those that are included will be more visible and will be explored in more detail. This combined with the significant number of new specimens being added means that many old mainstays had to be cut from the roster. Cuts occur for a variety of reasons, including eliminating redundancy, preserving specimens that were not faring well in the open-air exhibit space, and making specimens that have been behind glass for decades available to a new generation of researchers. Retired specimens are of course not going far – they have been relocated to the collections where students and scientists can study them as needed.

Stegomastodon (USNM 10707)

Stegomastodon in 2014. Photo by the author.

The Stegomastodon in 2014. Photo by the author.

The young male Stegomastodon is the largest single specimen that is being retired from the NMNH fossil halls. James Gidley and Kirk Bryan collected this skeleton in the San Pedro Valley of Arizona, during the same 1921 collecting trip that produced the museum’s Glyptotherium (which will be returning). While the genus Stegomastodon was erected in 1912, Gidley referred his specimen to a new species, S. arizonae, due to its more “progressive” physiology and slightly younger age. By 1925, the skeleton was mounted and on display in the Hall of Extinct Monsters. While the original mount used the real fossil tusks, these were eventually replaced with facsimiles.

There are at least two reasons the Stegomastodon will not be returning in 2019. First, there are already two big elephants on display: the mammoth and the mastodon. Elephants take up a lot of space, and a third proboscidean offers diminishing returns when compared to the amount of floor space it requires. More importantly, the Stegomastodon is a holotype specimen, and the exhibit team elected to remove most of these important specimens from the public halls. This is both to keep them safe from the damaging effects of vibration, humidity, and fluctuating temperature, as well as to make them more accessible to researchers.

Paramylodon (USNM V 15164)

Collections staff

Collections staff wheel Paramylodon out of the exhibit hall. Source

During the 1960s, Assistant Curator Clayton Ray oversaw the construction of the short-lived Quaternary Hall, which was reworked into the Hall of Ice Age Mammals. This meant creating a number of brand-new mounts, including several animals from the Rancho La Brea Formation in Los Angeles County. La Brea fossils are not found articulated, but as a jumble of individual elements preserved in asphalt. The Los Angeles Natural History Museum provided NMNH with an assortment of these bones, which preparator Leroy Glenn assembled into two dire wolves, a saber-toothed cat, and the sheep cow-sized sloth Paramylodon.

Paramylodon is another cut for the sake of eliminating redundancy: the two colossal Eremotherium completely overshadow this more-modestly sized sloth. This mount also needed some TLC. For aesthetic reasons, the Paramylodon was given an internal armature, which involves drilling holes through each of the bones. Last year, preparator Alan Zdinak took on the task of disassembling and conserving these damaged fossils with assistance from Michelle Pinsdorf.

Zygorhiza (USNM PAL 537887)

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Zygorhiza cast in the Life in the Ancient Seas gallery. Source

When the Life in the Ancient Seas gallery opened in 1990, it featured a historic Basilosaurus skeleton that had been on display since the 1890s. This ancestral whale was relocated to the Ocean Hall in 2008, and a cast of the smaller whale Zygorhiza took its place in Life in the Ancient Seas. Since there is now an extensive whale evolution exhibit in Ocean Hall, this subject will not be a major part of the new paleontology exhibit. Both Zygorhiza and the dolphin Eurhinodelphis will have to go.

After the old fossil halls closed, Smithsonian affiliate Mark Uhen managed to acquire the retired Zygorhiza mount for George Mason University, where he is a professor. The whale is now on display in the Exploratory Hall atrium, suspended 30 feet in the air.

Tapirs, Horses, and Oreodonts

Photo by the author.

The tapir Hyrachyus and the mini-horse Orohippus. Photo by the author.

The last two major renovations of the NMNH fossil exhibits occurred when mammal specialists were in charge of the Paleobiology Department, and as a result the halls ended up with a lot of Cenozoic mammal mounts (at least 50, by my count). Virtually every major group was covered, often several times over. This menagerie has been culled for the new hall, which will focus on specimens that best tell the story of Earth’s changing climate during the past 66 million years. Casualties include the trio of Hagerman’s horses, the smaller horse Orohippus, the tapirs Hyrachyus and Helaletes, the ruminant Hypertragulus, and the oreodont Merycoidodon. Interestingly, the classic hall’s three large rhinos are sticking around, and will in fact be joined by at least one more.

Brachyceratops (USNM 7953)

Brachyceratops/Rubeosaurus

Brachyceratops/Rubeosaurus. Photo by NMNH Department of Paleobiology.

The pocket-sized ceratopsian historically called Brachyceratops has been on display at NMNH since 1922. Discovered in 1913 by Curator of Fossil Reptiles Charles Gilmore, this animal is one of only a few dinosaur species excavated, prepared, described, and exhibited entirely in-house at NMNH. Assembled by Norman Boss, the mount is actually a composite of five individuals Gilmore found together in northeast Montana.

Gilmore described Brachyceratops as an unusually small but full-grown ceratopsian, but in 1997 Scott Sampson and colleagues confirmed that all five specimens were juveniles. Unfortunately, the fossils lack many diagnostic features that could link them to an adult form. According to Andrew McDonald, the most likely candidate is Rubeosaurus. Nevertheless, without the ability to recognize other growth stages of the same species, the name Brachyceratops is unusable and is generally regarded as a nomen dubium.

It is not difficult to surmise why the Brachyceratops would end up near the bottom of the list of specimens for the new exhibit. It is not especially large or impressive, it doesn’t have a recognizable name (or any proper name at all, really) and it doesn’t tell a critical story about evolution or deep time. With limited space available and new specimens being prepped for display, little Brachyceratops will have to go.

Corythosaurus (USNM V 15493)

Corythosaurus as seen in 1960s

Corythosaurus as seen in the 1960s. Photo courtesy of the Smithsonian Institution Archives.

In 1910, Barnum Brown of the American Museum of Natural History launched the first of several expeditions to the Red Deer River region of Alberta. Seeing Brown’s success and under pressure to prevent the Americans from hauling away so much of their natural heritage, the Canadian Geological Survey assembled their own team of fossil collectors in 1912. This group was headed by independent fossil hunter Charles Sternberg, who was accompanied by his sons George, Levi, and Charles Jr. Having secured several articulated and nearly complete dinosaur skeletons, Brown’s team moved on five years later. The Sternbergs, however, remained at the Red Deer River, and continued to collect specimens for the Royal Ontario Museum.

In 1933, Levi discovered a well-preserved back end of a Corythosaurus, complete with impressions of its pebbly skin. The Smithsonian purchased this specimen in 1937 for use at the Texas Centennial Exposition. It eventually found its way into the permanent paleontology exhibit at NMNH. Unfortunately, the half-Corythosaurus ended up crowded behind more eye-catching displays and was often overlooked by visitors. In the new exhibit, it will have to move aside to make room for new Cretaceous dinosaurs.

Assorted Dinosaur Skulls

Triceratops skull

Original skull of Hatcher the Triceratops, one of many dinosaur skulls coming off exhibit. Photo by the author.

In addition to complete dinosaur mounts, the old NMNH fossil halls included several dinosaur skulls, ranging from the giant cast of the AMNH Tyrannosaurus to the miniscule Bagaceratops. Most of these standalone skulls have been cut, although a few (Diplodocus, Camarasaurus, and Centrosaurus) are sticking around, to say nothing of new specimens being added. Other retirees in this category include the original skulls of Nedoceratops (labeled Diceratops), TriceratopsEdmontosaurus, and Corythosaurus, as well as casts of Protoceratops, Pachycephalosaurus, Stegoceras, Psittacosaurus, and Prenocephalae.

As usual, the reasons these specimens are coming off exhibit are varied. The Nedoceratops skull is a one-of-a-kind holotype that has been the subject of a great deal of conflicting research over its identity and relevance to Maastrichtian ceratopsian diversity. Putting this specimen back in the hands of scientists should help clarify what this bizarre creature actually is. Meanwhile, many of the other skulls (e.g. Protoceratops, Psittacosaurus, and Prenocephalae) come from Asian taxa. In the new fossil hall, the Mesozoic displays will primarily focus on a few well-known ecosystems in North America.

Dolichorynchops (USNM PAL 419645)

Dolichorhynchops from Montana, mounted by Arnie Lewis. Photo by Chip Clark.

Dolichorhynchops in the Life in the Ancient Seas exhibit. Photo by NMNH Department of Paleobiology.

The NMNH Dolichorhynchops is a relatively new mount. It was collected in Montana in 1977 and acquired in a trade with the Denver Museum of Nature and Science. Arnie Lewis prepared it for display in 1987. 24 years later, “Dolly” is being retired to the collections. This is not due to anything wrong with the specimen, but to make way for a bigger, cooler short-necked plesiosaur. NMNH purchased a cast of Rhomaleosaurus from the Henry Ward Natural Science Establishment in the 1890s, but it has not been on exhibit since at least 1910. This cast, which is based on an original at the National Museum of Ireland (and which is identical to the cast at the London Natural History Museum) will make its first public appearance in over a century in the new National Fossil Hall. Sorry, Dolichorhynchops.

This has hardly been a comprehensive list – just a few examples that illustrate the decisions that are made when planning a large-scale exhibit. If you are curious about other favorites from the old halls, you can check on their fate by searching the Department of Paleobiology’s online database. Just go to Search by Field and enter “Deep Time” under Collection Name to see most of the specimens earmarked for the new exhibit.

References

Gidley, J.W. 1925. Fossil Proboscidea and Edentata of the San Pedro Valley, Arizona. Shorter Contributions to General Geology (USGS). Professional Paper 140-B, pp. 83-95.

Gilmore, C.W. 1922. The Smallest Known Horned Dinosaur, BrachyceratopsProceedings of the US National Museum 63:2424.

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 Vol. 90.

Gilmore, C.W. 1946. Notes on Recently Mounted Reptile Fossil Skeletons in the United States National Museum. Proceedings of the United States National Museum Vol. 96 No. 3196.

McDonald, A.T. 2011. A Subadult Specimen of Rubeosaurus ovatus(Dinosauria: Ceratopsidae), with Observations on other Ceratopsids from the Two Medicine Formation. PLoS ONE 6:8.

Sampson, S.D., Ryan, M.J. and Tanke, D.H. 1997. Craniofacial Ontogeny in Centrosaurine Dinosaurs: Taxonomic and Behavioral Implications. Zoological Journal of the Linnean Society 12:1:293-337.

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Filed under collections, dinosaurs, exhibits, Extinct Monsters, fossil mounts, history of science, mammals, marginocephalians, museums, NMNH, ornithopods, reptiles, theropods

AMNH 5027 at 100

In December 1915, the American Museum of Natural History unveiled the very first mounted Tyrannosaurus rex skeleton, irrevocably cementing the image of the towering reptilian carnivore in the popular psyche. For a generation, AMNH was the only place in the world where one could see T. rex in person. Despite the tyrant king’s fame, old books emphasize the rarity of its fossils. The situation is very different today. In the last 30 years, the number of known Tyrannosaurus specimens has exploded. Once elusive, T. rex is now one of the best known meat-eating dinosaurs, and real and replica skeletons can be seen in museums around the world. The AMNH mount is no longer the only T. rex around, nor is it the biggest or most complete. It was, however, the first, and in a few weeks it will mark the 100th anniversary of its second life. Below is a partially recycled recap of this mount’s extraordinary journey.

Photo by the author.

AMNH 5027 in November 2015. Photo by the author.

The mount known as AMNH 5027 is actually a composite of material from two individuals. The first is the Tyrannosaurus rex holotype (originally AMNH 973, now CM 9380), which was discovered by Barnum Brown and Richard Lull during an AMNH expedition to Montana in 1902. The find consisted of little more than the pelvis, a single femur, one arm and shoulder, and fragmentary portions of the jaw and skull. Nevertheless, this was enough for AMNH director Henry Osborn to publish a brief description in 1905, as well as coin the species’ brilliantly evocative name. That same year, Adam Hermann prepared a plaster replica of the animal’s legs and pelvis, using Allosaurus fossils as reference when sculpting the missing lower legs and feet. This partial mount was initially displayed alongside the skeleton of a large ground bird, in order to accentuate the anatomical similarities.

Brown located a better Tyrannosaurus specimen in 1908. Apparently fearing poaching or scooping, Osborn wrote to Brown that he wished to “keep very quiet about this discovery, because I do not want to see a rush into the country where you are working.” After vanquishing many tons of horrific sandstone overburden, Brown returned to New York with what was at the time the most complete theropod specimen ever found. In addition to an “absolutely perfect” skull, the new find included most of the rib cage and spinal column, including the first half of the tail (Osborn 1916). Lowell Dingus would later describe this second specimen (the true AMNH 5027) as “a nasty old codger”, suffering from severe arthritis and possibly bone cancer. These pathologies were undoubtedly painful and probably debilitating.

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

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

Osborn initially wanted to mount both Tyrannosaurus specimens facing off over a dead hadrosaur. He even commissioned E.S. Christman to sculpt wooden models which which to plan the scene (shown above). 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. Instead, the available fossils complemented one another remarkably well in the construction of a single mounted skeleton. Osborn noted this good fortune in 1916, but his statement that the two specimens were “exactly the same size” wasn’t quite accurate. The holotype is actually slightly larger and more robust than the 1908 specimen, and to this day the AMNH Tyrannosaurus mount has oversized legs.

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

The original Tyrannosaurus rex mount at AMNH. Note the original 1905 replica legs in the background. Photo from Dingus 1996.

Instead, Hermann’s team prepared a single Tyrannosaurus mount, combining the 1908 specimen with the reconstructed pelvis and legs based on the 1905 holotype. When the completed mount was unveiled in 1915, the media briefly lost their minds. In contemporary newspapers, the skeleton was called “the head of animal creation”, “the prize fighter of antiquity”, and “the absolute warlord of the earth”, among similarly hyperbolic proclamations. Even Osborn got in on the game, calling Tyrannosaurus “the most superb carnivorous mechanism among the terrestrial Vertebrata, in which raptorial destructive power and speed are combined.” 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.

Image courtesy of the AMNH Archives.

T. rex in the Cretaceous Hall, 1960. Image courtesy of the AMNH Research Library.

The AMNH’s claim to the world’s only mounted Tyrannosaurus skeleton ended in 1941, when the holotype was sold to the Carnegie Museum of Natural History. The Pittsburgh museum’s hunch-backed reconstruction of the tyrant king was on display within a year. Although no longer the only T. rex on display, the AMNH mount certainly remained the most viewed as the 20th century progressed. It became an immutable symbol for the institution, visited again and again by generations of museum goers. Its likeness was even used as the iconic cover art of Michael Crichton’s Jurassic Park.

By the 1980s, however, a new wave of dinosaur research had conclusively demonstrated that these animals had been active and socially sophisticated. The AMNH fossil galleries had not been updated since the 1960s, and the upright, tail-dragging T. rex in particular was painfully outdated. AMNH had once been the center of American paleontology, but now its displays were lagging far behind newer museums.

finished mount, room under construction

Restoration of AMNH 5027 was completed nearly three years before the hall reopened. Photo from Dingus 1996.

Between 1987 and 1995, Lowell Dingus coordinated a comprehensive, $44 million renovation of the AMNH fossil exhibits. As part of the project, chief preparator Jeanne Kelly led the restoration and remounting of the most iconic specimens, Apatosaurus and Tyrannosaurus. Of the two mounts, the Tyrannosaurus presented the bigger challenge. The fossils were especially fragile, and some elements, specifically the cervical vertebrae, had never been completely freed from the sandstone matrix. It took six people working for two months just to strip away the layers of shellac applied by the original preparators. All told, the team spent a year and a half dismantling, conserving, and rebuilding the T. rex.

Phil Fraley’s exhibit company constructed the new armature, which gave the tyrant king a more accurate horizontal posture. While the original mount was supported by obtrusive rods extending from the floor, the new version is actually suspended from the ceiling by a pair of barely-visible steel cables. Playing with Christman’s original wooden models, curators Gene Gaffney and Mark Norrell settled on a fairly conservative stalking pose, imbuing the mount with a level of dignity befitting this historic specimen. The restored AMNH 5027 was completed in 1992, but would not be unveiled to the public until the rest of the gallery was finished in 1995. Since that time, tens of millions of visitors have flocked to see this new interpretation of Tyrannosaurus. This is the skeleton that showed the world that dragons are real, and it is still holding court today.

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.F. 2008. Tyrannosaurus rex: A Century of Celebrity. Tyrannosaurus rex, The Tyrant King. Larson, Peter and Carpenter, Kenneth, eds. Bloomington, IN: Indiana University Press.

McGinnis, H.J. 1982. Carnegie’s Dinosaurs: A Comprehensive Guide to Dinosaur Hall at Carnegie Museum of Natural History, Carnegie Institute. Pittsburgh, PA: The Board of Trustees, Carnegie Institute.

Norell, M, Gaffney, E, and Dingus, L. 1995. Discovering Dinosaurs in the American Museum of Natural History. New York, NY: Alfred A. Knopf, Inc.

Osborn, H.F. 1906. Tyrannosaurus, Upper Cretaceous Carnivorous Dinosaur: Second Communication. Bulletin of the American Museum of Natural History vol. 22, pp. 281-296.

Osborn, H.F. 1913. Tyrannosaurus, Restoration and Model of the Skeleton. Bulletin of the American Museum of Natural History vol 32, pp. 9-12.

Osborn, H.F. 1916. Skeletal Adaptations of Ornitholestes, Struthiomimus, and TyrannosaurusBulletin of the American Museum of Natural History vol 35, pp. 733-771.

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Filed under AMNH, dinosaurs, fossil mounts, history of science, museums, theropods

The Nation’s T. rex Revealed

The Nation's T. rex was temporarily assembled in the RCI workshop for inspection by Smithsonian staff. Source

The Nation’s T. rex was temporarily assembled in the RCI workshop for inspection by Smithsonian staff. Source

Yesterday, a press embargo lifted and the world got it’s first look at the pose the Nation’s T. rex will assume in the new fossil hall at the National Museum of Natural History. I don’t have much to add to the solid coverage at The Washington Post, NPR, and Smithsonian Magazine except holy crap, that’s awesome.

The photo above (by Nikki Kahn of The Washington Post) was taken when Smithsonian staff visited the Research Casting International workshop to inspect the mount’s progress. Located outside of Toronto, RCI is the industry leader in the art of creating mounted fossil skeletons, and their work is on display in museums all over the world. The Nation’s T. rex is one of 52 mounts the company will create for NMNH over the next three years.

Dr. Carrano gestures toward the awesomeness behind him.

Dr. Carrano gestures toward the awesomeness behind him. Source

The Nation’s T. rex (also known as Wankel Rex) is new to NMNH, but it is not a new specimen. It was discovered by Montana rancher Kathy Wankel in 1988 on land owned by the Army Corps of Engineers. The skeleton, which was for a time the most complete Tyrannosaurus known, was held in trust at the Museum of the Rockies until last April, when the Corps loaned the specimen to the Smithsonian for the next 50 years. This is the first time the original fossils have been displayed in a standing mount, but RCI has been producing casts of the specimen for years. Examples can be seen at the Great North Museum, the Royal Ontario Museum, the Perot Museum of Nature and Science, and even the Google Campus.

The Smithsonian team inspecting every inch of the 2,000 pound mount included Curator of Dinosauria Matt Carrano, Exhibit Project Manager Siobhan Starrs, and Preparator Steve Jabo. The violent scene, with the Tyrannosaurus preparing to decapitate its Triceratops prey, was first suggested by Carrano over two years ago. The inspiration came from research by Denver Fowler and colleagues, which proposed that Tyrannosaurus regularly dismembered Triceratops by pulling the head off by the frill. The dynamic pose sets the Nation’s T. rex apart from the more “regal” stances other museums have chosen for their Tyrannosaurus mounts, and also reminds visitors that this animal was a living, acting being within its environment.

A 3-D printed model of the skeleton was used to plan the pose. Source

The exhibit team used a 3-D printed model of the skeleton to plan the pose. Source

The tyrant king’s prey is none other than a cast of Hatcher, NMNH’s resident Triceratops. This composite skeleton was the first mounted Triceratops ever exhibited, and it has been on display in one form or another since 1905. An updated reproduction of Hatcher can be seen right now in The Last American Dinosaurs, but apparently this will be its last hurrah. As Carrano put it, “Hatcher’s done its duty.” Even relegated to the role of food, however, Hatcher is still an impressive beast. The skeleton is nearly as long as the Nation’s T. rex, and noticeably bigger than the Triceratops mounts at other major U.S. museums.

Hatcher Photo by the author.

Poor Hatcher knows nothing of his imminent demise at the claws of a 38-foot murderbird. Photo by the author.

The NMNH team had a few notes for RCI, both for the sake of accuracy and the sake of the exhibit. Carrano requested that the fibula be rotated slightly, while Starrs emphasized that the tail should be at least 10 feet off the ground, to prevent over-enthusiastic visitors from grabbing at it. The workshop visit was also an opportunity to explore how the mount would look among the other denizens of the National Fossil Hall. Hatcher and the Nation’s T. rex will be sharing space on the Creataceous platform with Edmontosaurus, Thescelosaurus, and the crocodile relative Champsosaurus, among others. Working out dynamic poses that also keep key lines of sight open is no easy task, and the gallery space needs to be planned down to the inch.

As is now industry standard, RCI’s armature is made up of intricate steel cradles that are custom fitted to hold each of the 150 real fossils in place. Unlike many historic mounts, no holes have been drilled in the bones and none of the delicate fossils are supporting the structure’s weight. Most bones can be removed individually, and with the right equipment, the entire mount can be assembled in just a few hours. As such, we can rest assured that this display will not only be incredibly cool, but the authentic 66 million-year-old fossils will be as safe as they could possibly be while on view for 7 million visitors per year.

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Filed under dinosaurs, exhibits, fossil mounts, marginocephalians, museums, NMNH, theropods

Denver’s Fighting Dinosaurs

Allosaurus and Stegosaurus mount

Allosaurus and Stegosaurus mounts at the Denver Museum of Nature and Science. Source

Just a quick post today to keep the blog moving. The Allosaurus and Stegosaurus skeletons at the Denver Museum of Nature and Science are among my all-time favorite fossil mounts. While there is no shortage of fighting dinosaur displays today, these mounts were something of a novelty when they were unveiled in 1995 as the centerpieces of the trendsetting “Prehistoric Journey” exhibition. A far cry from the stiff, macabre trophies that had dominated paleontology exhibits since the beginning of the 20th century, the Allosaurus and Stegosaurus plainly represent swift and active animals. Unlike many similar scenes, however, the action here is tempered with careful attention to anatomical detail: no limbs are hyperextended, and no bones are out of place.

The Stegosaurus

A postcard showing STegosaurus in the 50s

This postcard shows the original Stegosaurus mount around 1950.

High school teacher Frank Kessler discovered the Stegosaurus (DMNH 1483) in 1937 while leading a nature hike north of Cañon City. While the Garden Park region had been known for its Jurassic dinosaur fossils since the days of O.C. Marsh and E.D. Cope, Kessler’s find was in a previously unexplored area. Kessler contacted the Denver Museum of Natural History (now the DMNS), and Robert Landberg was dispatched to lead a thorough excavation. Landberg eventually recovered a 70% intact Stegosaurus, in addition to a multitude of turtles, crocodiles, and isolated dinosaur bones.

Back in Denver, Phillip Reinheimer assembled the Stegosaurus fossils into a standing mount. A former steelworker from Pittsburgh, Reinheimer was initially hired by the museum to maintain the furnaces, but eventually proved to be an uncommonly talented fossil preparator. Described by Johnson and Stucky as “a master craftsman,” Reinheimer remains something of a legend among preparators to this day. Reinheimer completed the Stegosaurus mount in 1938, and it remained a focal point of the museum’s fossil exhibits for decades afterward. In 1982, this specific specimen was named the state fossil of Colorado.

The Allosaurus

A close up of Allosaurus

Another look at Allosaurus and Stegosaurus. Source

In 1979, 13 year-old India Wood discovered and identified an Allosaurus skeleton on her family’s ranch in Moffat County, Colorado. She excavated the find herself over a period of three years, until her mother encouraged her to reach out to the DMNS. After seeing the fossils Wood had been collecting in a box under her bed, paleontology curator K. Don Lindsay agreed to excavate the rest of the skeleton.

The project took two more summers to complete, and Wood remained an active participant. Although many at the museum remember being impressed by her knowledge and talent, Wood ultimately did not pursue paleontology as a career – she instead went on to earn an MBA from MIT and founded a business consulting firm. Meanwhile, Wood’s Allosaurus (DMNH 2149) remained in storage for more than a decade – until it was selected to feature in an ambitious new exhibit.

Prehistoric Journey

From left to right

From left to right: Wood’s Allosaurus, Karen Alf, Bryan Small, Jon Christians, Jerry Harris, Jennifer Moerman, Ken Carpenter, and Kessler’s Stegosaurus. Image from Johnson and Stucky 2013.

The DMNS had been a powerhouse of paleontology research in the early and mid 20th century, but by the 1980s its reputation had slipped away. That changed in 1989 when Richard Stucky came on board as the new Curator of Vertebrate Paleontology. Stucky brought order to the museum’s historic collections, and laid out plans for a comprehensive new exhibit entitled “Prehistoric Journey.” He also hired a new pool of talent to make the project happen, including paleontologist and preparator Ken Carpenter. As Chief Preparator, Carpenter was tasked with moving, restoring, and in some cases remaking the classic Reinheimer mounts, including the Kessler Stegosaurus. The DMNS crew also ventured into the field to collect new material for Prehistoric Journey. Among the most impressive finds was a new Stegosaurus (DMNH 2818), discovered by Bryan Small at Garden Park only a few hundred yards from where the Kessler specimen was unearthed. This articulated specimen clarified for the first time the position of the animal’s plates and spikes, and also confirmed that Stegosaurus had throat armor made up of tiny hexagonal ossicles. All of this informed the remounting of the Kessler Stegosaurus.

Carpenter’s take on this classic specimen paired it with India Wood’s Allosaurus, right in the middle of the Prehistoric Journey dinosaur gallery. The Stegosaurus is shown defending two (largely reconstructed) juveniles from the attacking theropod, while five or six Othnielia (casts) flee the scene. Twenty years after its 1995 debut, this scene is still among the most impressive fossil mounts around because of the seemingly effortless way it captures action and behavior. Carpenter and his colleagues did not only restore the shape of these animals but breathed life into them. The viewer cannot help but imagine the events that preceded this encounter, as well as the eventual outcome. The suspended bones are like brush strokes in an impressionist painting, swooping through the space and imbuing it with energy and motion. The fact that these are mostly original fossils rather than lightweight casts makes the display all the more impressive. I’ve said it many times before, but it bears repeating that fossil mounts are fascinating, challenging objects in that they are both authentic specimens and interpretive creations. In many cases these conflicting identities are jarring. However, with the right amounts of artistry, aptitude, and solid science, a fossil mount can transcend this juxtaposition and serve each identity equally well. Not an easy feat, but the DMNS Stegosaurus and Allosaurus are a defining example of the craft.

References

Carpenter, K. (1998). Armor of Stegosaurus stenops and the Taphonomic History of a New Specimen from Garden Park, Colorado. Modern Geology Vol. 22: pp. 127-144.

Johnson, K.R. and Stucky, R.K. (1995). Prehistoric Journey: A History of Life on Earth. Golden, CO: Fulcrum Publishing.

Johnson, K.R. and Stucky, R.K. (2013). Paleontology: Discovering the Ancient History of the American West. Denver Museum of Nature and Science Annals No. 4: pp. 231-282..

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Filed under dinosaurs, DMNS, fossil mounts, museums, theropods, thyreophorans

A Trio of Tyrants

The frentic search for North American dinosaur fossils in the late 19th and early 20th centuries can be divided into three phases. First came O.C. Marsh and E.D Cope, whose infamous rivalry resulted in literal trainloads of fossil material and laid the groundwork for our present understanding of dinosaur diversity. Next, teams sponsored by the newly-formed American, Carnegie, and Field museums returned to the same hunting grounds in the western interior to secure display-worthy specimens for their great halls of exhibition. The final phase was smaller in scale but yielded dinosaur specimens so spectacularly complete that most have gone unmatched to this day.

This third fossil rush occurred not in the United States but in Canada, along the cliff-like banks of Alberta’s Red Deer River. Fossil hunting in this region was pioneered in the late 1800s by George Dawson, Joseph Tyrell, and Lawrence Lambe, all working for the Canadian Geological Survey. This success did not go unnoticed by the the American Museum of Natural History’s Department of Vertebrate Paleontology. In 1910, the museum mounted an expedition led by Barnum Brown to the Red Deer River. Rather ingeniously, Brown’s team acquired a pair of 30-foot floating barges, which were used as mobile platforms from which they could excavate the steep river banks. The barges also served as floating campsites and a handy means of transportation in a region without reliable roads.The adventurous Brown was already a media favorite, and the publicity surrounding his Alberta expeditions only increased when the team started bringing back fully articulated and nearly complete dinosaur skeletons (including several with skin impressions).

Under pressure from constituents concerned that the Americans were hauling away so much of their natural heritage, the Canadian government formed its own team of fossil collectors in 1912. The new Canadian Geological Survey team was headed by independent fossil hunter Charles H. Sternberg (a veteran collector who had once worked for Cope) and his sons George, Levi, and Charles Jr. The Canadian and American teams worked in the same region for the next five field seasons. Their rivalry was usually good-natured, but on more than one occasion Brown saw fit to grumble about the Sternbergs’ ethics (never mind that he was the one permanently removing fossils from their country of origin).

Gorgosaurus at AMNH

Three tyrannosaurs mounted in relief at AMNH. Image courtesy of the AMNH Research Library.

All of this is so much preamble for the actual topic of this post – three remarkable Gorgosaurus skeletons* collected near the Red Deer River during the Canadian fossil rush. All three were eventually mounted in relief by AMNH preparator Peter Kaisen, and for a time they were displayed together in the Hall of Fossil Reptiles. These specimens are on the short list of most complete large theropod dinosaurs ever discovered, and in their day they provided researchers an unprecedented look at the physiology of these amazing animals. Nearly a century later, the three mounts are virtually unchanged. Locked behind glass for decades and largely inaccessible to researchers, the mounts themselves are now relics of a fascinating transitional period in the history of dinosaur studies.

*AMNH also recovered a fourth tyrannosaur during this period – Gorgeous George the Daspletosaurus.

As usual, a brief explanation of nomenclature is required. William Matthew and Barnum Brown originally described these specimens as Gorgosaurus, a genus that Dale Russell sank into Albertosaurus in 1970. Most specialists no longer support this synonymization, but the specimens at AMNH are still labeled as Albertosaurus.

Gorgosaurus libratus – USNM 12814

gorgo

A recent photo of USNM 12812 from the ongoing renovation of the national fossil hall. Source

USNM 12814 (originally designated AMNH 5248) was excavated by Brown’s company in 1913 and prepared for display in 1918. Kaisen elected to recreate the death pose in which the Gorgosaurus was found, with its head swept backward over its body. All told, the finished mount included a skull, a complete set of cervical and dorsal vertebrae, complete forelimbs, and a single femur – the pelvis and the rest of the hindlimbs were filled in with casts from other specimens. Since the skeleton was mounted in relief, Kaisen simply painted the tail onto the backdrop.

After at least a dozen years on display at AMNH, the Gorgosaurus was traded to the National Museum of Natural History as part of a complicated deal between the two museums. While surveying fossil collections throughout the United States, Brown realized that a single Barosaurus skeleton from Dinosaur National Monument had been divided among three different institutions. NMNH had the neck and part of one forelimb, the Carnegie Museum had the tail, and the University of Utah had the rest. Between 1929 and 1933, Brown arranged a series of trades in order to unify the Barosaurus at AMNH. The Smithsonian in particular drove a hard bargain – the museum had already invested $3400 in preparing their Barosaurus section, and paleontology staff wanted a good return for their investment. Brown’s initial offer was the fully prepared and mounted Gorgosaurus. Although AMNH valued the field and prep time spent on the fossils at $4573, it was at that point a duplicate specimen taking up valuable space in their increasingly crowded exhibit hall.

NMNH dinosaur specialist Charles Gilmore confided in Brown that he was okay with this trade, but fellow Smithsonian paleontologist Alexander Wetmore wasn’t sold. For years, NMNH staff had been trying to acquire one of the many Moropus specimens AMNH had collected at the Agate Fossil Beds in Nebraska. NMNH had offered a variety of specimens to trade, even sending AMNH a set of brontothere skulls at one point, but AMNH was adamant the Moropus fossils could only be exchanged for cash. Brown really wanted that Barosaurus neck, so in January of 1933, he finally relented and offered the Smithsonian a largely complete Moropus in addition to the Gorgosaurus. Not long after, the Gorgosaurus relief mount found its way into the Hall of Extinct Monsters at NMNH.

Gorgosaurus sp. – AMNH 5458

albertosaurus

A technician (probably Kaisen) adjusts the steel strap holding the femur in place. Source

Brown’s team found their second Gorgosaurus near Steveville, Alberta in 1914. Complete save for the left leg, right arm, and parts of the rib cage and tail, the mount was ready for display in May of 1921. At 24 feet long and 14 feet high, this was by far the largest relief mount at the museum. In fact, it was too big to fit through the workshop doorway in one piece, so Kaisen constructed it in eight sections that were sealed together in the exhibit hall. Each section had its own wooden frame for support, and the bones themselves were held in place with steel straps. The skull, jaw, and left forearm could be removed for individual study. This was unusual for the period (most contemporary fossil mounts were designed to be permanent) and speaks volumes about this specimen’s unique scientific value.

This mount is particularly notable for its awkward running pose. Directly contradicting many narratives of early 20th century paleontology, Matthew and Brown envisioned Gorgosaurus as an animal that “walked and ran much like a gigantic bird.” The AMNH team posed this mount after studying photos of bipedally running lizards, particularly the western tiger lizard*. However, Matthew and Brown noted that the dinosaur’s  limb proportions and range of motion more closely resemble a bird than a lizard, and adjusted the pose accordingly. They also advised a more conservative stride length to compensate for the animal’s considerable weight.

*Matthew and Brown do not provide a scientific name, and the common name “western tiger lizard” doesn’t seem to be used any more. Anyone know what it’s called today?

The final pose was a compromise between the elevated torso of a running lizard and the comparatively tight gait of a bird. It looks more than a little strange, but AMNH 5458 is certainly closer to our present understanding of theropod posture than most mounts of the era. Matthew and Brown’s interpretation of Gorgosaurus turned out to be ahead of its time. Some contemporary researchers, including Lawrence Lambe, declared the running pose to be highly improbable, and virtually all theropod mounts constructed over the next 60 years returned to the tail-dragging posture of the 1915 AMNH Tyrannosaurus.

Gorgosaurus sternbergi” – AMNH 5664

gorgo sternbergi

Gorgosaurus “sternbergi” as it was discovered and originally mounted. Source

The most complete tyrannosaur from the Red Deer River was not collected by the AMNH party, but by the Sternbergs. The elder Charles Sternberg discovered the specimen in 1917, entirely intact save for the left arm and the very end of the tail. In fact, this was the most complete large theropod ever found in North America until it was surpassed by yet another Gorgosaurus, TCM 2001.89.1. Sternberg first attempted to sell the specimen to the British Museum. They weren’t interested, but AMNH was. In 1918, the Department of Vertebrate Paleontology bought the skeleton for $2000, thus completing the tyrannosaur trio.

Matthew and Brown described AMNH 5664 as a new species – Gorgosaurus sternbergi. In their 1921 publication, they describe the skull as longer and shallower than other Gorgosaurus specimens, with rounder orbits. However, Brown and Matthew recognized that these could be juvenile characteristics, noting as well that the unfused pelvic bones were an indication of immaturity. As early as 1970, this specimen was suspected to be a juvenile Gorgosaurus (or Albertosaurus) libratus.

Kaisen prepared the relief mount in 1921, this time assisted by Carl Sorenson. The photo above shows the original version of this mount, with the tail projecting straight back from the body. This was how Sternberg discovered the skeleton, and Kaisen wanted to keep the death pose intact. In the 1950s, the tail was “corrected” to make it drag on the ground. Although the display has not been altered since, the revised tail posture is now considered inaccurate. Indeed, the vertebrae apparently had to be angled unnaturally to make the dragging tail work at all.

AMNH 5027 was restored and remounted in 1995.

The Gorgosaurus plaque mounts hide behind Tyrannosaurus rex at AMNH. Photo by the author.

All three Gorgosaurus specimens were first displayed in the cramped quarters of the Hall of Fossil Reptiles (now the Hall of Primitive Mammals) with the rest of the growing AMNH dinosaur collection (USNM 12814 and the tail of AMNH 5664 are barely visible in this photo). 5458 and 5664 moved to the newly opened Great Hall of Dinosaurs in 1922. They flanked the gallery’s rear doorway for 70 years before being moved to the Hall of Saurischian Dinosaurs in 1994. Meanwhile, the Gorgosaurus transferred to the Smithsonian first appeared in the Hall of Extinct Monsters in the 1940s, displayed behind glass on the north wall. It switched to the south side in 1962, and moved about 30 feet up the wall in 1981, where it could only be properly seen from the mezzanine ramp.

Aside from the aforementioned alternation to AMNH 5664’s tail, the Red Deer River Gorgosaurus trio has not been modified since they were first built. This may well change in the not-to-distant future. The NMNH crew is hard at work on a thorough renovation of the national fossil hall, dismantling and restoring all of the classic dinosaur mounts. Meanwhile, the current AMNH paleontology exhibits are now 20 years old, and will soon be due for a similar overhaul. Both institutions will need to decide whether or not to free the Gorgosaurus specimens from their plaster substrate. This would be an extremely difficult process, but not impossible – Phil Fraley Productions recently rebuilt the Carnegie Museum’s Corythosaurus, Dryosaurus, and Camptosaurus as free-standing mounts. Dismantling the relief mounts would give a new generation of scientists access to these important specimens, and it would allow for the skeletons to be given more accurate poses. In addition, a standing Gorgosaurus mount alongside either museum’s Tyrannosaurus rex would be both informative and awesome.

Nevertheless, remaking these mounts would also destroy significant historical context. The carefully restored death pose of USNM 12812 seems like something worth preserving, and the AMNH specimens represent an important transitional period in the history of dinosaur science. In the past, museums have often taken a “science marches on” approach when updating aging displays, but in these mounts might be unique enough in their current form to be left as-is. What do you think?

References

Carr, T.D. (1999). Craniofacial Ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19: 497-520.

Colbert, E.H. (1968). Men and Dinosaurs: The Search in Field and Laboratory. New York, NY: E.P. Dutton & Co., Inc.

Gilmore, C.W. (1946). Notes on Recently Mounted Reptile Fossil Skeletons in the United States National Museum. Proceedings of the United States National Museum Vol. 96 No. 3196.

The Long Road to a Fossil Swap. Digging the Fossil Record, March 19, 2015. http://nmnh.typepad.com/smithsonian_fossils/2015/03/gorgosaurus-and-moropus.html

Matthew, W.D. and Brown, B. (1923). Preliminary Notices of Skeletons and Skulls of Deinodontidae from the Cretaceous of Alberta. American Museum Noviates 89: 1-10.

Russell, D. (1970). Tyrannosaurs from the Late Cretaceous of western Canada. National Museum of Natural Science Publications in Palaeontology 1: 1–34.

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Filed under AMNH, dinosaurs, field work, fossil mounts, history of science, museums, NMNH, reptiles, theropods