Category Archives: field work

Extinct Monsters: Gilmore’s Diplodocus

Click here to start the Extinct Monsters series from the beginning.

More than 80 years ago, Smithsonian paleontologist Charles Whitney Gilmore supervised the installation of the mounted Diplodocus skeleton known as USNM 10865. In December 2014, that same skeleton was finally disassembled for conservation and eventual re-mounting.This post is about the history of this particular mount: where it came from, who put it together, and what it has and continues to tell us about prehistory.

Predecessor at CMNH

The story of the NMNH Diplodocus mount actually began in Pittsburgh, Pennsylvania around the turn of the century. In November of 1898, Steel tycoon-turned-philanthropist Andrew Carnegie read that the remains of a giant “Brontosaurus” had been discovered in Wyoming. Carnegie’s interest was piqued and the following year, he contributed $10,000 to the Carnegie Museum of Natural History (which he had founded two years earlier) to find a complete “Brontosaurus” – or something like it – for display in Pittsburgh. Perhaps proving that money can indeed buy anything, on July 4th, 1989 the CMNH team found a reasonably complete sauropod skeleton in Sheep Creek Basin, Wyoming. CMNH Curator of Paleontology John Bell Hatcher declared the specimen to be a new species, which he named for the Museum’s benefactor: Diplodocus carnegii.

Back in Pittsburgh, the task of preparing and mounting the fossils fell to preparator Arthur Coggeshall and his staff.  Creating a permanent armature for a delicate 84-foot skeleton was a monumental undertaking, beyond anything that had ever been attempted before. Coggeshall used a steel rod, shaped to the contours of the vertebral column, as the basis for the mount. Once the backbone was in place, the limbs, ribs, and other extremities were mounted on steel rods of their own and attached to the rest of the skeleton. The fossils were connected to the steel armature by drilling screws and bolts directly into the bone. Since the original Diplodocus carnegii skeleton was not complete, the mount was supplemented with fossils uncovered during subsequent field seasons at Sheep Creek and elsewhere in Wyoming.

The CMNH Diplodocus was unveiled in 1907 in a brand-new wing that had been constructed to display it. Although the American Museum of Natural History had by that point completed a sauropod mount of their own, the Pittsburgh display was well-received by paleontologists and laypeople alike. Not to be bested by the New York competition, Carnegie also commissioned eight Diplodocus replicas, which he donated to museums throughout Europe and Latin America.

The original CMNH Diplodocus mount, in the hall built specifically to accomodate it. Source

The original CMNH Diplodocus mount, in the hall built specifically to accommodate it. Source

This wave of publicity allowed the paleontology staff at CMNH and elsewhere to continue to undergo large-scale fossil hunting expeditions. In 1909, a team led by Earl Douglass hit the jackpot north of Jensen, Utah. At the site now known as Dinosaur National Monument, CMNH teams excavated over 300 tons of Jurassic fossils over 13 field seasons. The immensely productive “Dinosaur Quarry” site is thought to represent a prehistoric river bar, where dead animals from upsteam accumulated over time. In addition to an assortment of crocodiles and other small reptiles, this location has yielded remains of Apatosaurus, Diplodocus, Stegosaurus, Allosaurus and many other taxa. Although the site was far from exhausted, the CMNH team moved on in 1922, at which point paleontologist Charles Gilmore from the United States National Museum took over.

USNM Excavation at Dinosaur National Monument

Gilmore led the first USNM field season at Dinosaur National Monument in May of 1923. In their final year at the site, the CMNH team had located two partial sauropod skeletons. Gilmore opted to focus on excavating these “in order to secure a mountable skeleton” for display (Gilmore 1932). As with the CMNH team before them, the primary motivation of Gilmore’s team was not scientific research, but to bring back spectacular display specimens. Gilmore was unarguably a phenomenal scientist who made lasting contributions to our knowledge about prehistory, but this focus on impressive displays was typical of early 20th century paleontology. As such, valuable taphonomic and ecological data that would been collected by modern paleontologists was probably destroyed when unearthing this and other exhibition-caliber dinosaur specimens.

Once the excavation began, Gilmore decided that the Diplodocus skeleton dubbed specimen 355 was the best candidate for a mount. The skeleton consisted of an articulated vertebral column, from the 15th cervical to the 5th caudal, a separated but virtually complete tail, the pelvis, both pectoral girdles, much of the rib cage, both humeri, and a complete left hind limb. Unfortunately, the head and most of the neck had eroded out of the hillside and  long since weathered away. Some elements not preserved with specimen 355 were reportedly cherry-picked from another specimen at the same site. Again, this sort of selective excavation is discouraged today, but was typical at the time. On August 8, the team wrapped up and shipped 25 tons of material back to Washington, DC via railway.

Preparation, Mounting and Description

Preparing and mounting the Diplodocus was, according to Gilmore, the single most ambitious undertaking attempted by the department during his tenure.  In his words, “the magnitude of the task, by a small force, of preparing one of these huge skeletons for public exhibition can be fully appreciated only by those who have passed through such an experience” (Gilmore 1932).  Gilmore, along with preparators Norman Boss, Thomas Horne, and John Barrett, spent  2,545 working days over the course of six years preparing the skeleton for exhibition. Gilmore reported that his team  followed the method Arthur Coggeshall had developed at CMNH over 20 years earlier for mounting their sauropod. The vertebral column was assembled first, supported by a series of steel rods. This structure was mounted at the appropriate height on four upright steel beams securely anchored to the floor. Limbs and other extremities were subsequently added, with steel rods shaped to the contours of the fossils supporting each portion of the skeleton.

Diplodocus under construction, ca. 1930. Source

Diplodocus under construction, ca. 1930. Source

Missing parts of the skeleton, including the right hindlimb and the distal portions of the forelimbs, were filled in using casts of the Carnegie Diplodocus. According to Gilmore, the casted elements were colored “to harmonize with the actual bones but with sufficient difference to be at once distinguished from the originals” (Gilmore 1932). This is noteworthy, because the creators of other dinosaur mounts at that time had been known to deliberately disguise artificial elements by painting them to match the fossils. Although the Smithsonian Diplodocus was a composite of multiple specimens and therefore does not represent any single animal that actually existed, the decision to make the casted elements readily visible represents a degree of honesty and integrity that is more common in modern museum displays than it was in Gilmore’s time.

Gilmore presents plans for the in-progress Diplodocus mount at the 1927 Conference of the Future of the Smithsonian. Photo courtesy of the Smithsonian Institution Archives.

In the process of preparing and mounting the Diplodocus (at this point designated USNM 10865), Gilmore was able to further refine our understanding of sauropod physiology. Looking at the specimen, Gilmore was easily able to dismiss notions by earlier workers that Diplodocus had sprawled like a crocodile, asserting that “the crocodilian attitude for Diplodocus involves anotomical imposibilities” (Gilmore 1932). Additionally, since the entire dorsal portion of the vertebral column was present and intact, Gilmore determined that the presacral vertebrae (in the lower back) arch downward, toward the sacrum. The CMNH Diplodocus and AMNH Apatosaurus had been mounted with completely straight backs, so Gilmore was able to create a more accurate mount. Studying the articulated vertebral column also convinced Gilmore to raise the tail higher than in previous sauropod mounts. Although it would be decades before paleontologists started raising the tail completely clear of the ground, this was certainly a step in the right direction. Gilmore refrained, however, from definitively assigning USNM 10865 to a particular species of Diplodocus, since at the time (and to this day, apparently) the differences among the named species of this genus were unclear.

Exhibition and Legacy

USNM 10865 in the Hall of Extinct Monsters, circa 1932. Photo courtesy of the Smithsonian Institution Archives.

The completed Diplodocus skeleton was 70 feet, 2 inches long and 12 feet, five inches tall at the hips, making it about 14 feet shorter in length than its CMNH counterpart. The mount was introduced to the Hall of Extinct Monsters at the United States National Museum in 1931, positioned atop three pedestals so that visitors could walk right underneath it. The Diplodocus was placed right in the center of the  gallery, facing west so that it could stare down visitors as they entered the hall.

The unveiling of the Diplodocus mount was a big deal, but did not catch the public’s attention in quite the same way as its CMNH predecessor. After all, by 1931 several of the other major natural history museums had had sauropods on display for over two decades. Nevertheless, for residents and visitors in Washington, DC the new mount was an unforgettable look at the life of the past.

The Diplodocus, as it stood from 1963 through 1981. Image courtesy of the Smithsonian Institution Archives.

The Diplodocus, as it stood from 1963 through 1981. Image courtesy of the Smithsonian Institution Archives.

The Diplodocus was not moved during the 1963 modernization of the fossil exhibits, but the walkable area around the mount was significantly reduced. Visitors could no longer walk under the skeleton, or get as close to it. The Diplodocus was not moved during the 1981 renovation, either, but the neck support coming up from the floor was replaced by less intrusive cables suspended from the ceiling. In the new exhibit, the sauropod centerpiece was surrounded by contemporaneous friends from the Morrison Formation, including Stegosaurus, Camptosaurus, Camarasaurus and Allosaurus.

National Museum of Natural History in Washington, DC.

Diplodocus as it stood from 1981-2014. Photo by the author.

From 1931 to 2014, the Diplodocus remained an unchanging fixture of the Museum’s east wing. Although this specimen’s story has not been as widely told as that of the CMNH Diplodocus, the Smithsonian sauropod is certainly just as interesting. For more than 80 years, USNM 10865 has mesmerized generations of viewers with its size and elegance.  What’s more, this specimen, and the associated measurements and drawings meticulously prepared by Gilmore, are frequently referred to in publications by modern paleontologists. For its contributions to public education and to scientific inquiry, USNM 10865 is one to celebrate.


Brinkman, P.D. The Second Jurassic Dinosaur Rush: Museums and Paleontology in America at the Turn of the 20th Century. Chicago: University of Chicago Press, 2010.

Gilmore, C.W. “On a Newly Mounted Skeleton of Diplodocus in the United States National Museum.” Proceedings of the United States National Museum 81:1-21, 1932.

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


Filed under anatomy, CMNH, dinosaurs, exhibits, Extinct Monsters, field work, fossil mounts, history of science, museums, NMNH, reptiles, sauropods

A brief history of mounted dinosaur skeletons

Mounted fossil skeletons, especially those of dinosaurs, are common at medium and large natural history museums. These mounts play a central role in the public’s perception of not only dinosaurs and other prehistoric animals, but of museums as well. However, just as dinosaurs are relatively new to science, fossil mounts have not always been a part of museums. The word dinosaur was coined in 1842 by British anatomist Richard Owen, based on a handful of fragmentary remains of large, extinct reptiles. Nevertheless, the study of dinosaurs did not start in earnest until 1865, when Joseph Leidy of Philadelphia’s Academy of Natural Sciences described Hadrosaurus, the first dinosaur found in the United States, and eventually, the first dinosaur skeleton to be mounted. The western frontier of North America proved to be a richer dinosaur hunting ground than Europe had been, and so vertebrate paleontology was among the first realms of science that American researchers could claim as their own.

The American fossil rush that followed came in two waves. In the 1870s, the field was dominated by the well-publicized but ultimately counterproductive feud between Othneil Charles Marsh of Yale and Edward Drinker Cope of the Academy of Natural Sciences. While these collectors amassed enormous collections of fossils for their respective institutions, their research remained largely out of the public eye.

1868 Hadrosaurus mount at the Academy of Natural Sciences. From

The second wave came at the turn of the 20th century, and was intrinsically related to the rise of the large museums that sprang up in America’s cities at this time. The American Museum of Natural History in New York, the Carnegie Museum of Natural History in Pittsburgh, the Field Museum of Natural History in Chicago and other, similar institutions became involved in a fierce competition to find and display the largest dinosaur (Spalding 1993). At this point, the discipline of paleontology had been marginalized in American universities, in part because of a rising interest in experiment-driven “hard” sciences like molecular biology and physics, but also because the demands of space, labor and money required by paleontological research was prohibitive.

1905 Brontosaurus mount at AMNH. From Dinosaur Tracking.

Instead, paleontologists made their homes at the large natural history museums, which were backed by wealthy benefactors who were impressed by their collections of giant fossils. At the time, it was fashionable for wealthy businesspeople to donate extravagantly to cultural institutions, including museums, in the cities where they made their fortunes. To the benefactors, there was no doubt that paleontologists and their fossil specimens could draw larger crowds than a chemist or physicist ever could. Steel tycoon Andrew Carnegie is credited with conceiving of the idea to display a mounted dinosaur skeleton as the centerpiece of his new museum in Pittsburgh. Carnegie gave CMNH $10,000 to find a giant sauropod dinosaur, preferably just like the Apatosaurus (then called “Brontosaurus”) collected by Marsh 30 years earlier. Patrons of the other large museums followed suit, and by 1905 the Carnegie Museum, the American Museum and the Field Museum all had sauropod mounts on display, along with a menagerie of other dinosaurs and prehistoric animals.

Unfortunately, by modern standards these displays favored spectacle over good science. As mentioned, vertebrate fossils almost never found as complete skeletons, but as scattered and isolated elements. As such, the museum collectors were not racing to find a single, perfect skeleton, but to amass enough individual dinosaur bones to complete a mount. The early 20th century dinosaur mounts are typically composed of fossils found in rocks separated by hundreds of miles and millions of years in age. The collectors did not keep good records of where the fossils came from, so modern museum workers can only guess how many individual dinosaurs make up the mounts they have inherited. For example, the Stegosaurus at the Peabody Museum of Natural History is composed of at least five individuals, and researchers disagree whether the Giraffatitan  at Berlin’s Museum fur Naturkunde is made up of three or five different animals.

A preparator at AMNH assembles the “Brontosaurus” mount. From

Additionally, the technicians that created the mounts were attempting something that had never been done before, and perhaps inevitably, poor choices were made during the construction process. Adam Hermann, lead fossil preparatory at the American Museum of Natural History during the early 20th century, used highly destructive techniques when creating fossil mounts. Fossils were connected to steel armatures by drilling screws and bolts directly into the bone, and broken bones and visible sections of the armature were hidden with liberal applications of plaster (Evander 2004). These practices turned out to be essentially irreversible, and modern workers are hesitant to attempt to dismantle old mounts for fear of destroying the fossils entirely.

The creation of the first fossil mounts was chiefly inspired by the vanity of museum benefactors, but their influence on audiences and their ability to draw crowds is undeniable. Although new dinosaur mounts have been constructed over the course of the 20th century, many, if not most, of the historic mounts remain on display, important not only as evidence of prehistoric life, but as icons of the history of science and museums in America.


Brinkman, Paul D. (2010.) The Second Jurassic Dinosaur Rush: Museums and Paleontology in America at the Turn of the 20th Century. Chicago, IL: University of Chicago Press.

Evander, Robert L. (2004.) “Armature Damage in a Mounted Specimen.” Presented at Society of Vertebrate Paleontology Annual Conference, Bristol, U.K.

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Filed under dinosaurs, field work, fossil mounts, history of science, mammals, museums, reptiles, science communication


Over the past couple months, as I have hoped in vain that the folks at SV-POW will post cool stuff about sauropods again, I’ve learned a great deal about open-access publishing and the Research Works Act. Kudos to them for creating awareness. The sinister implications of the RWA are well documented around the web, so I’ll just provide the short version.

At present, taxpayer funded research institutions in the U.S., namely the NIH, require that research results must be freely accessible online. This is a reasonable requirement that is hard to argue against: if the public pays for science, the public should be able to see the results. However, this open-access policy gets in the way of the profits of the academic publishing industry. Publishers like Elsevier and Springer have astonishingly high profit margins of 36% or more, dwarfing even those of Apple, and they aim to keep them that way. Academic publishers have a pretty sweet scam going, in which (largely publicly funded) researchers supply the papers and the peer review for free, while the publishers take the full copyright, and charge $30-$50 to view a single article. All the publisher does is format the manuscripts into a physical volume, which is irrelevant since most people now access papers online. Enter RWA, an effort by publishers to push back against increasing awareness of their unnecessary and monopolistic role as gatekeepers of knowledge.

Until this point, the voices of dissent from the academic community seemed to paint a fairly straightforward picture. Researchers, who know the academic publishing industry well, are more-or-less unanimously opposed to the unbridled corporate greed represented by the RWA. But then this business happened (.pdf link). The American Anthropological Association, with which I’ve taken issue before, has thrown in its lot on the side of the publishers. The previously linked AAA statement was a response to the U.S. Office of Science and Technology Policy’s ongoing Request for Information (check out all the responses to date here). The AAA claims that there is currently no problem with the accessibility of research, and that it is unfair to undermine the right of publishers to sell their property at market value. Here are the choice quotes:

We write today to make the case that while we share the mutual objective of enhancing the public understanding of scientific enterprise and support the wide dissemination of materials that can reach those in the public who would benefit from such knowledge (consistent with our association’s mission), broad public access to information currently exists, and no federal government intervention is currently necessary.

Mandating open access to such property without just compensation and lawful procedural limits constitutes, in our view, an unconstitutional taking of private property – copyrighted material – an expropriation without fair market compensation. In our view, such a practice cannot and will not withstand judicial review.

Both of these arguments are nonsense. If the AAA believes that “those in the public who would benefit from such knowledge” currently have appropriate access to research, then their definition of the public must end at researchers at large institutions. As articulated at Neuroanthropology, this insular view is unhelpful and unacceptable, and it is particularly surprising that it is coming from a group of anthropologists. Do the non-profit groups anthropologists work with in developing countries not require access to papers? What about the people the research is about? Interested lay-people? Under the current system, and to an even greater extent should the RWA pass, anybody not affiliated with an institution with a well-funded library* has to pay exorbitant prices out of pocket to view research. As a result, the research remains largely in the academic sphere. Given the political nature of anthropologists in general, it is shocking that the AAA deems this acceptable.

*Side note: Even as a grad student, getting access to papers can be a real problem. Even large universities sometimes only provide access to volumes of journals within a certain date range, and when I’m doing field work or an internship, I can no longer get access.

The second quote is bunk because, as explained previously, the services provided by academic publishers are minimal, if not counterproductive to the dissemination of knowledge, and do not constitute anything that researchers could not do themselves in this information age.

As they did a year ago when they removed the reference to science from their mission statement, the AAA has demonstrated that their interests are not in sync with researchers. Honestly, I don’t know who they are trying to represent. They are working against the interests of serious researchers, advocacy groups who help the people anthropologists work with, and the dissemination of knowledge in general. AAA, please stop.

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Pictures from the field

Just a few pictures from my time fossil prospecting in NE Arizona. Ain’t that desert pretty? More on why the late Triassic and microstrat is cool later.

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