Category Archives: sauropods

Bully for Camarasaurus

Note: This post was written in 2014. It predates Emanuel Tschopp’s landmark paper which, among other things, resurrected the genus “Brontosaurus.” I’ve attempted to update the taxonomy where appropriate, but it may still be a bit of a mess.

The story of the mismatched head of Brontosaurus is one of the best known tales from the history of paleontology. I think I first heard it while watching my tattered VHS copy of More Dinosaurs – scientists had mistakenly mounted the skull of Camarasaurus on an Apatosaurus skeleton, and the error went unnoticed for decades. The legend has been repeated countless times, perhaps because we revel in the idea that even experts can make silly mistakes. Nevertheless, I think it’s time we set the record straight: nobody ever mistakenly placed a Camarasaurus skull on Apatosaurus. The truth is a lot more nuanced – and a lot more interesting – than a simple case of mistaken identity.

Intrinsically related to the head-swap story is the replacement of “Brontosaurus” with “Apatosaurus” in the popular lexicon. This is well covered elsewhere, so I’ll be brief. Scientific names for animals are governed by the International Code of Zoological Nomenclature, which includes the principle of priority: if an organism has been given more than one name, the oldest published name is the correct one. Leading 19th century paleontologist O.C. Marsh named Apatosaurus ajax in 1877, based on a vertebral column discovered in the Morrison Formation of Colorado. Two years later, Marsh introduced Brontosaurus excelsus to the world, from a more complete specimen uncovered in rocks of the same age in Wyoming. Like many of Marsh’s publications, these descriptions were extremely brief, offering a scant two paragraphs for each taxon. However, Marsh did provide a longer description of Brontosaurus in 1883, complete with the first-ever restoration of the complete skeleton.

This is not a Camarasaurus skull.

Come play with us, Brontosaurus…forever and ever and ever. Photo courtesy of the AMNH Research Library.

In 1903, Elmer Riggs of the Field Museum of Natural History underwent a survey of sauropod fossils held at various east coast museums and concluded that Brontosaurus excelsus was too similar to Apatosaurus to merit its own genus. The name “Brontosaurus” was dropped, and the species became Apatosaurus excelsus for most of the 20th century. However, a substantial re-evaluation of diplodocoid sauropods by Emanuel Tschopp and colleagues in 2015 reversed Riggs’ decision. So the name Brontosaurus is back, but keep in mind that the species excelsus never actually went anywhere – it was just hidden under the Apatosaurus umbrella. Following Tschopp et al., Apatosaurus and Brontosaurus were distinct animals that lived in the same environment.

So how does the mismatched head fit into all of this? The short answer is that it doesn’t. The fact that some Apatosaurus mounts had incorrect heads for much of the 20th century has nothing to do with which name was being used at any given time, although the two issues have often been conflated in popular books. I suspect the two stories got mixed up because paleontologists were pushing to correct both misconceptions around the same time during the dinosaur renaissance.

Marsh's Brontosaurus

Marsh’s second and definitive Brontosaurus reconstruction, first published in 1891.

Let’s go back to Marsh’s 1891 Brontosaurus reconstruction*, pictured above. The Brontosaurus type specimen did not include a head, and many have reported that Marsh used a Camarasaurus skull in this illustration. However, this would not have been possible, because the first complete Camarasaurus skull wasn’t discovered until 1899. What Marsh had instead were a few fragmentary bits of Camarasaurus cranial material, plus a snout and jaw (USNM 5730) now thought to be Brachiosaurus (more on this at SV-POW). Although these pieces were found far from the Brontosaurus quarry, Marsh extrapolated from them to create the best-guess skull that appears in his published reconstruction.

*Note that this is the second of two “Brontosaurus” reconstructions commissioned by Marsh. The first drawing, published in 1883, has somewhat different skull, but it still does not resemble Camarasaurus. 

Although the venerable Stephen Gould states in his classic essay “Bully for Brontosaurus” that Marsh mounted the Brontosaurus holotype at the Yale Peabody Museum, Marsh never saw his most famous dinosaur assembled in three dimensions. In fact, Marsh strongly disliked the idea of mounting fossil skeletons, considering it a trivial endeavor of no benefit to science. Instead, it was Adam Hermann of the American Museum of Natural History, supervised by Henry Osborn, who built the original Brontosaurus/Apatosaurus mount (AMNH 460), six years after Marsh’s death in 1899.

Counterclockwise from top:

Clockwise from top: AMNH sculpted skull (Source), Peabody Museum sculpted skull, real Apatosaurus skull (Source), and real Camarasaurus skull.

To create the mounted skeleton Hermann combined fossil material from four separate individuals. All of the material had been collected by AMNH teams in Wyoming specifically for a display mount  – and to beat Andrew Carnegie at building the first mounted sauropod. Like Marsh, however, they failed to find an associated skull (a Camarasaurus-like tooth was allegedly found near the primary specimen, but it has since been lost). Even today, sauropod skulls are notoriously rare, perhaps because they are quick to fall off and roll away during decomposition. Instead, Hermann was forced to sculpt a stand-in skull in plaster. Osborn explained in an associated publication that this model skull was “largely conjectural and based on that of Morosaurus” (Morosaurus was a competing name for Camarasaurus that is no longer used).

Was it really, though? The sculpted skull is charmingly crude, so the overt differences between the model and a real Camarasaurus skull (top and bottom left in the image above) might be attributed to the simplicity of the model. Note that there isn’t even an open space between the upper and lower jaws! Still, Hermann’s model bears a striking resemblance to Marsh’s illustration in certain details, principally the elongate snout and the very large, ovoid orbit. It certainly isn’t out of the question that Hermann used Marsh’s speculative drawing as a reference, in addition to any actual Camarasaurus material that was available to him. At the very least, it is incorrect to say that AMNH staff mistakenly gave the mount a Camarasaurus skull, since Osborn openly states that it is a “conjectural” model.

A young Mark Norell

A young Mark Norell leads the removal of the sculpted skull from the classic AMNH Apatosaurus. Source

In 1909, a team led by Earl Douglass  of the Carnegie Museum of Natural History finally discovered a real Apatosaurus skull (third image, lower right). They were working at the eastern Utah quarry that is now Dinosaur National Monument, excavating the most complete Apatosaurus skeleton yet found (CM 3018). The skull in question (cataloged as CM 11162) was not connected to the skeleton, but Douglass had little doubt that they belonged together. Back at the Carnegie Museum, director William Holland all but confirmed this when he found that the skull fit neatly with the skeleton’s first cervical vertebra. As he wrote at the time, “this confirms…that Marsh’s Brontosaurus skull is a myth.”

The Carnegie team prepared and mounted the new Apatosaurus, and Holland initially planned to use the associated skull. However, when Osborn heard about this he threatened to ruin Holland’s career if he went through with it. You see, the new skull looked nothing like the round, pseudo-Camarasaurus model skull on the AMNH mount. Instead, it was flat and broad, like a more robust version of Diplodocus. Osborn wasn’t about to let Holland contradict his museum’s star attraction, and Holland backed down, never completing his planned publication on the true nature of Apatosaurus. Meanwhile, the mounted skeleton at the Carnegie Museum remained headless until Holland’s death in 1932. After that, museum staff quietly added a Camarasaurus-like skull. This was an important event, as it would be the first time an actual casted skull of Camarasaurus (as opposed to a freehand sculpture) would be attached to a mounted Apatosaurus skeleton. While I’ve had no luck determining precisely who was involved, Keith Parsons speculated that the decision was made primarily for aesthetic reasons.

Carnegie Museum Brontosaurus circa 1934. Source

Carnegie Museum Apatosaurus alongside the famed Diplodocus, sometime after 1934. Source

Elmer Riggs assembled a third Apatosaurus mount (FMNH P25112) at the Field Museum in 1908. Riggs had recovered the articulated and nearly complete back end of the sauropod near Fruita, Colorado in 1901, but was unable to secure funding for further collecting trips to complete the mount. Riggs was forced to mount his half Apatosaurus as-is, and the absurd display stood teetering on its back legs for 50 years. Finally, Riggs’ successor Orville Gilpin acquired enough Apatosaurus fossils to complete the mount in 1958. As usual, no head was available, so Gilpin followed the Carnegie Museum’s lead and gave the mount a casted Camarasaurus skull.

The completed mount as it stood in the 1970s, Camarasaurus head and all.

Orville Gilpin finally completed the FMNH Apatosaurus in 1958.

The last classic apatosaurine mount was built at the Yale Peabody Museum of Natural History in 1931, using Marsh’s original Brontosaurus excelsus holotype (YPM 1980) and a lot of plaster padding. The skull this mount originally sported (third image, upper right) is undoubtedly the strangest of the lot. A plaster replica sculpted around a small portion of a real Camarasaurus mandible, this model doesn’t look like any known sauropod. The overall shape is much more elongated than either Camarasaurus or the AMNH model, and may have been inspired by Marsh’s hypothetical illustration. Other details, however, are completely new. The anteorbital fenestrae are thin horizontal slashes, rather than the wide openings in previous reconstructions, while the tiny, forward-leaning nares don’t look like any dinosaur skull – real or imaginary – I’ve ever seen. The sculptor is sadly unknown, but this model almost looks like a committee-assembled combination of the Marsh drawing, the AMNH model, and CM 11162 (a.k.a. the real Apatosaurus skull).

During the mid-20th century, vertebrate paleontology lapsed into a quiet period. Although the aging dinosaur displays at American museums remained popular with the public, these animals came to be perceived as evolutionary dead-ends, of little interest to the majority of scientists. The controversies surrounding old mounts were largely forgotten, even among specialists, and museum visitors saw no reason not to accept these reconstructions (museums are, after all, one of the most trusted sources of information around).

A postcard

The Peabody Brontosaurus with its original head. Note that the Camarasaurus in the foreground also has a sculpted skull.

This changed with the onset of the dinosaur renaissance in the 1970s and 80s, which brought renewed energy to the discipline in the wake of new evidence that dinosaurs had been energetic and socially sophisticated animals. In the midst of this revolution, John McIntosh of Wesleyan University re-identified the real skull of Apatosaurus. Along with David Berman, McIntosh studied the archived notes of Marsh, Douglass, and Holland and tracked down the various specimens on which reconstructed skulls had been based. They determined that Marsh’s restoration of the Brontosaurus skull, long accepted as dogma, had in fact been almost entirely arbitrary. Following the trail of guesswork, misunderstandings, and scientific inertia, McIntosh and Berman proved that Holland had been right all along. The skull recovered at Dinosaur National Monument along with the Carnegie Apatosaurus was in fact the only legitimate skull ever found from this animal. In 1981, McIntosh himself replaced the head of the Peabody Museum Brontosaurus with a cast of the Carnegie skull. AMNH, the Field Museum, and the Carnegie Museum followed suit before the decade was out.

aess

Remounted Apatosaurus at the Carnegie Museum. Photo by the author.

Given the small size of the historic community of dinosaur specialists, it may have been particularly vulnerable to the influences of a few charismatic individuals. To wit, Marsh’s speculative Brontosaurus skull was widely accepted despite a lack of compelling evidence, and Osborn was apparently able to bully Holland out of publishing a find that contradicted the mount at AMNH. What’s more, the legend of the mismatched Brontosaurus skull somehow became distorted by the idea that either Marsh or Osborn had accidentally given their reconstructions the head of Camarasaurus. This is marginally true at best, since both men actually oversaw the creation of composite reconstructions which only passingly resembled Camarasaurus. Nevertheless, the idea that the skull of Camarasaurus was a passable substitute for that of Apatosaurus was apparently well-established by the 1930s, when Carnegie staff hybridized the two sauropods for the first time. Even today, there are numerous conflicting versions of this story, and it is difficult to sort out which details are historically accurate and which are merely assumed.

I’d like to close by pointing out that while the head-swap story is often recounted as a scientific gaffe, it is really an example of science working as it should. Although it took a few decades, the mistakes of the past were overcome by sound evidence. Despite powerful social and political influences, evidence and reason eventually won out, demonstrating the self-corrective power of the scientific process.

References

Berman, D.S. and McIntosh, J.S. 1975. Description of the Palate and Lower Jaw of the Sauropod Dinosaur Diplodocus with Remarks on the Nature of the Skull of ApatosaurusJournal of Paleontology 49:1:187-199.

Brinkman, P. 2006. Bully for Apatosaurus. Endeavour 30:4:126-130.

Gould, S.J. 1991. Bully for Brontosaurus: Reflections in Natural History. New York, NY: W.W. Norton and Company.

Osborn, H.F. 1905. Skull and Skeleton of the Sauropodous Dinosaurs, Morosaurus and BrontosaurusScience 22:560:374-376.

Parsons, K.M. 1997. The Wrongheaded Dinosaur. Carnegie Magazine. November/December:38.

Tschopp, E., Mateus, O., and Benson, R.B.J. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3:e857. https://doi.org/10.7717/peerj.857

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Filed under AMNH, CMNH, dinosaurs, field work, FMNH, fossil mounts, history of science, museums, reptiles, sauropods, systematics

The Diplodocus seen around the world

1st cast in spot of honor

The first cast of the Carnegie Diplodocus holds court at London’s Natural History Museum. Source

The story of Andrew Carnegie’s Diplodocus will surely be well known to most readers. As the legend goes, Carnegie the millionaire philanthropist saw a cartoon in the November 1898 New York Journal depicting a sauropod dinosaur peering into the window of a skyscraper. He immediately contacted the paleontology department at the newly established Carnegie Museum of Natural History in Pittsburgh, and offered ample funding to find a sauropod skeleton for display. So began a frantic competition among the United States’ large urban museums to be the first to collect and mount a sauropod – the bigger the better.

The American Museum of Natural History was first across the finish line, unveiling their composite “Brontosaurus” in February of 1905. By that time, the Carnegie team had already found a sauropod skeleton of their own, a Diplodocus, near Medicine Bow, Wyoming. Unfortunately, they had nowhere to display it, as the Carnegie Museum building was still far from finished. Unwilling to be bested by his New York competition, Andrew Carnegie offered his chum King Edward VII a complete plaster replica of the Diplodocus, and hired a team of modelmakers to help make it happen. The arrival of the facsimile Diplodocus at the British Museum (now the Natural History Museum) in London was celebrated with a white tie event presided over by Carnegie and Baron Avebury, who spoke on behalf of the king. The London Diplodocus was on display two months after the AMNH “Brontosaurus”, and the original skeleton was unveiled in Pittsburgh in 1907.

diplodocus_nocopyright

In March 1905, a classy shindig celebrated the arrival of the first replica Diplodocus in London.

That’s usually where the Diplodocus story ends, with a footnote that nine more Diplodocus replicas were later manufactured and presented to heads of state throughout Europe and Latin America. I’d like to explore those subsequent displays in more detail. The Carnegie Diplodocus was the first mass-produced dinosaur, and by 1932 it appeared in no less than ten virtually identical displays across three continents. Taylor characterizes Carnegie’s sauropod as “the single most viewed skeleton of any animal in the world”, and its scientific, social, and even political ramifications are both wide-reaching and fascinating.

Building a Sauropod

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

The real CM 84 has been displayed in Pittsburgh since 1907. Source

The Diplodocus in question is specimen CM 84, recovered in 1899 in Albany County, Wyoming. The skeleton was about 60% intact and remains one of the most complete sauropod specimens ever found. The ubiquitous John Bell Hatcher described the fossils in 1901, coining the new species Diplodocus carnegiei after the project’s benefactor. Arthur Coggeshall of the Carnegie Museum was primarily responsible for preparing and casting the fossils. He was initially supervised by Hatcher, but William Holland took over when Hatcher died in 1904. Holland deferred to Hatcher’s judgement in most cases, although he was not shy about voicing his disagreement. For example, Hatcher had reconstructed the Diplodocus forefeet with slightly elevated digits, but Holland (incorrectly) thought they should be flat and splayed.

As is typical of dinosaur mounts, the incomplete primary specimen was supplemented with other fossils to produce a full skeleton. The skull, for instance, was a cast of USNM 2673, a specimen that was until recently on display at the Smithsonian. A number of missing bones, including most elements of the forelimbs, were sculpted using a smaller Diplodocus specimen for reference. Although it took longer to produce than the AMNH “Brontosaurus”, contemporary paleontologists generally agreed that Carnegie’s Diplodocus was the superior sauropod mount. Not only was it’s pose more natural and lifelike, but the underlying steel armature was cleverly hidden. It’s difficult to overstate the challenges of assembling a mounted skeleton on this scale, and in its day the Diplodocus was the best in the world.

Roll Call

dip_mexico

The Chopo University Museum in Mexico City received the 9th Diplodocus cast in 1929. Source

As mentioned, the first replica Diplodocus was unveiled in London in 1905, and the original fossils were ready for display in 1907. French and German dignitaries were present at an event in Pittsburgh celebrating its completion, and Andrew Carnegie promised both countries Diplodocus casts of their own. Once again, Coggeshall and Holland led the creation of the new mounts, a task they would repeat many times in the years to come. Playing precisely to cartoonish national stereotypes, the Germans provided a detailed plan and ambitious schedule for the project, while the French acted coy, then threw a lavish party when the mount was ready. Diplodocus replicas were on display at the National Natural History Museum in Paris and the Humboldt Museum in Berlin before the end of 1908, but the Pittsburgh team already had orders for a new batch of mounts. By early 1910, three new Diplodocus were on exhibit at the Museum for Paleontology and Geology in Bologna, Italy, the Natural History Museum in Vienna, Austria, and the Zoological Museum in St. Petersburg, Russia. The La Plata Museum in Buenos Aires, Argentina and the National Museum of Natural Science in Madrid, Spain received their Diplodocus mounts in 1912 and 1913, respectively, bringing the total number of replicas up to eight by the onset of World War I.

The war put a damper on this friendly exchange of dinosaurs, and Carnegie’s death in 1919 brought the Diplodocus diaspora to a temporary end. However, in 1929 Louise Carnegie, wife of Andrew, commissioned an additional cast as a gift for Alfonso Herrera of the Chopo University Museum in Mexico City. Herrera originally asked for a bronze cast for outdoor display, but when this proved prohibitively expensive, a plaster version was produced instead. In 1932, the Carnegie Museum traded a Diplodocus replica for a collection of German fossils from the Paleontological Museum in Munich. This copy has never been mounted or displayed. The last Diplodocus cast from the original molds was forged in 1957. Made from concrete, this mount was displayed outdoors for many years at the Utah Field House Museum in Vernal, Utah.

goofy vernal field house concrete cast

The 11th and final facsimile Diplodocus made from the original molds was this concrete version, on exhibit in Vernal, Utah for many years.

Most of the historic Diplodocus mounts remain on display today. The London Diplodocus was taken off exhibit during World War II, but in 1979 it was given a position of honor in the museum’s entrance hall. Later, it was completely restored and remounted with its tail held aloft. The Berlin, Buenos Aires, and Bologna Diplodocus mounts have also been upgraded with modern poses, but the others retain their historic, tail-dragging posture, looking exactly as they did a century ago. The St. Petersburg mount was circulated among a number of Russian museums, and may have been destroyed in an effort to make new molds from the bones (Edit: The Russian mount is still on display at the Orlov Museum for Paleontology – see comments). The concrete Diplodocus in Vernal has likewise been retired, but it was used to create two new casted skeletons, now on display in Utah and Nevada.

Opportunities for Science

St. Petersburg

The weird bow-legged Diplodocus in St. Petersburg looks more like the original USNM Triceratops than Tornier’s take on the sauropod.  Source

The sudden availability of identical Diplodocus skeletons presented an unusual opportunity for international scientists, allowing researchers based thousands of miles apart to study and compare notes on the same bones. Perhaps inevitably, a few European scientists were not happy with Holland and Coggeshall’s take on the sauropod. The best-known dissenter was Gustav Tornier, who rejected the straight-limbed reconstruction of Diplodocus, arguing instead that the sauropod sprawled like a crocodile. The German scientist provided an illustration of this alternate stance, in which the poor dinosaur’s arms appear to project from the base of its neck. Holland responded with a particularly harsh rebuttal (backed by several European scientists), and Tornier declined to push the issue further in print.

Rather than risk Holland’s wrath in writing, in at least one case local researchers may have quietly modified their Diplodocus mount after the Americans installed it (Warning: speculation ahead). The St. Petersburg Diplodocus once sported bizarrely bowed forelimbs and a strongly arched back. Holland himself directed the assembly of each and every Diplodocus mount*, and based on his impassioned (and occasionally ad-hominem laced) writing on the subject, it seems quite unlikely that he would have permitted this deviation from his standard design. Even a request from the National Natural History Museum in Paris to curl the sauropod’s tail to save space met with some hand-wringing on his part, so I can only surmise that St. Petersburg mount was altered sometime after Holland’s work was finished.

*Holland was definitely present during the initial assembly of the St. Petersburg Diplodocus, as he more than once recounted an incident in which a Russian worker almost dropped one of the steel supports on him (Edit: This may not have happened – see comments).

Dinosaurs for everyone

La plata

Diplodocus cast number seven at the La Plata Museum in Buenos Aires. Source

The most lasting influence of the Carnegie Diplodocus is certainly it’s cultural impact. If any one specimen can be credited with inspiring the global popularity of dinosaurs, it was this one. Thanks to Carnegie, citizens of 11 different nations had their first opportunity to stand in the presence of a giant dinosaur, and to experience the scale and splendor of a creature that completely dwarfed any modern land animal. In every nation where a new Diplodocus was installed, the local press adored the creature, never failing to point out it’s tiny head and presumed stupidity. Diplodocus was an endearing oaf, and for a time, its name was synonymous with dinosaurs and prehistory in general.

What was the significance of Diplodocus to all these people? It’s difficult not to think of it as a vanity project for Andrew Carnegie*, an opportunity to rub shoulders with European royalty and flaunt his wealth and generosity. One might also consider the Diplodocus an expression of America’s economic and technological might, or perhaps a harbinger of the United States’ role in globalization and mass production. French writer Octave Mirbeau seemed to be thinking along those lines when he lamented the mighty dinosaur being reduced to a crass, populist display. According to Carnegie himself, however, the goal was nothing less than world peace: he wanted to bring people together over their shared enthusiasm for the dinosaur. Too bad World War I came along and ruined the sauropod love-in.

*If the accolades went to anyone’s head, it was Holland’s. During his world tour assembling sauropod mounts, he was given countless awards, including the French Legion of Honor and German Knight’s Cross. Holland carefully added each new medal to his portrait at the Carnegie Museum.
Original Diplodocus

The original Diplodocus skeleton was remounted at the Carnegie Museum in 2007. Photo by the author.

On both sides of the Atlantic, Diplodocus was a shared point of reference and a beloved symbol. Most commonly, Diplodocus was the butt of a joke: from politicians to athletes to heavy machinery, anything big and slow and not especially bright was likened to the dinosaur. My favorite anecdote on the subject comes from Nieuwland: during World War I, soldiers from different nations with different languages had the word “Diplodocus” in common, and used it to describe the heavy, plodding tanks.

Today, we think of Diplodocus and its ilk very differently. Sauropods weren’t ungainly dolts – they were surprisingly nimble and extremely successful megaherbivores, unchallenged in their dominance for 140 million years. Still, it’s difficult to think of single fossil that has matched the global cultural impact of CM 84. There are far more copies of Stan the T. rex on display, and Sue is widely known by name, but really, the only contender that even comes close is Archaeopteryx. With eleven versions still on display, Carnegie’s legendary Diplodocus lives on.

References

Brinkman, P.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.

Holland, W.J. 1906. The osteology of Diplodocus Marsh with special reference to the restoration of the skeleton of Diplodocus carnegiei Hatcher, presented by Mr. Andrew Carnegie to the British Museum, May 12, 1905. Memoirs of the Carnegie Museum. Vol. 2, No. 6, 225-278.

Nieuwland, I. 2010. The colossal stranger: Andrew Carnegie and Diplodocus intrude European Culture, 1904-1912. Endeavour. Vol 34, No. 2.

Taylor, M.P. 2010. Sauropod dinosaur research: a historical review. Geological Society, London, Special Publications. Vol. 343, pp. 361-386.

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Filed under CMNH, dinosaurs, fossil mounts, history of science, museums, reptiles, sauropods

What’s the deal with Astrodon?

In Laurel, Maryland, a trail of banners depicting a herd of the sauropod dinosaur Astrodon johnstoni leads the way to Dinosaur Park, the site of a historically significant fossil deposit. At the Maryland Science Center in Baltimore, a life-sized Astrodon sculpture towers over the “Dinosaur Mysteries” exhibit. And since 1998, Astrodon has been the official state dinosaur of Maryland, joining other state symbols like the black-eyed susan and Baltimore oriole. In short, Astrodon is a sort of mascot for mid-Atlantic paleontology. Named in 1858 for fossils found in a Prince George’s County iron mine, the appeal of Astrodon for Marylanders is obvious: it’s a home-grown dinosaur in a region that is not widely recognized for its fossil resources, and the story of its discovery also calls attention to the state’s industrial heritage.

But what sort of animal was Astrodon, and how much do paleontologists truly know about it? Compared to many other extinct animals found around the world, the fossil record for Astrodon is and always has been fairly poor. The name Astrodon was first bestowed upon nothing more than isolated teeth, and although other fragmentary remains attributed to Astrodon have been uncovered over the past 150 years, reconstructions of the Maryland sauropod are mostly derived from the fossils of relatives found elsewhere. What’s more, the name Astrodon has a convoluted history, having been applied haphazardly to fossils found across the country and even around the world. For these reasons, some paleontologists would prefer that the name Astrodon not be used at all.

Lacking a scientific consensus on what sort of animal the Maryland sauropod was or even what it should be called, I find myself in a difficult position as an educator. How can the messy and contentious taxonomy of Astrodon be condensed into something teachable? Is simplifying or downplaying this controversy doing our audience a disservice, and to what degree?

The taxonomic history of Astrodon

The first scientifically recognized North American dinosaur fossils were found in the Mid-Atlantic region, a scant 17 years after dinosaurs were first recognized as a biological group in 1842. Joseph Leidy’s Hadrosaurus from the New Jersey coast is credited as the first American dinosaur to be described, but Astrodon was a close second. During the mid-19th century, iron mining was big business in central Maryland. Miners extracted large boulders of siderite, or iron ore, from open pit mines throughout Prince George’s County, and these miners were the first in the region to discover dinosaur bones and teeth. The siderite was being mined from clay deposits now known as the Arundel Formation, part of the larger Potomac Group that extends throughout Maryland (the Potomac Group was laid down during the Early Cretaceous period, between 125 and 113 million years ago). Members of the Maryland Academy of Sciences recognized the fossils from the Arundel clay as similar to the English fossil reptiles that Richard Owen had recently unified as Dinosauria. In 1858, academy member Christopher Johnston published a description of a set of teeth from the iron mines in the American Journal of Dental Science, which he named “Astrodon” (Joseph Leidy turned this informal name into a proper binomial, Astrodon johnstoni, in his 1865 review of North American fossil reptiles).

Today, most paleontologists consider it poor judgment to name a new taxon based only on teeth. When scientists describe a newly discovered organism, they designate a type specimen, which is used to define that taxon in perpetuity. But when the type specimen is especially fragmentary, or only consists of a small part of the organism, it poses a problem for future researchers. In the case of Astrodon, no newly discovered fossils other than teeth can be confidently referred to the same species. In 1858, however, paleontological norms were very different. All dinosaur fossils known at the time were exceedingly incomplete: scientists knew that dinosaurs were reptiles and that they were very big and not much else. Any new fossils, even teeth, represented a major addition to our understanding of the life appearance and diversity of these extinct animals. For modern paleontologists, Johnston’s published description of the Astrodon teeth is vague and uninformative, but in his day, these fossils were distinct from anything else yet known.

Astrodon teeth lower left.

Astrodon teeth are on the lower left.

In December of 1887, famed paleontologist Othneil Charles Marsh sent his best fossil hunter, John Bell Hatcher, to search the area in Prince George’s County where Astrodon was discovered. Judging from Hatcher’s journal entries, he didn’t have a great time. It rained and snowed almost constantly, and on several days his team didn’t bother to show up for work. Although Hatcher managed to find numerous dinosaur, crocodile and turtle fossils, these finds did not match the quality of the fossils Hatcher had been finding in the western states, and no return trips were made. Nevertheless, Marsh saw fit to name two new dinosaur species from the material Hatcher collected: Pluerocoelus altus and Pluerocoelus nanus. Neither taxon was named for material that would be considered diagnostic if found today: P. altus was based on a tibia and fibula, while P. nanus was based on four nonadjacent vertebrae.

By this time, more complete dinosaur fossils from the American west were beginning to reveal a clearer picture of dinosaur diversity. Based on the shape and size of the fossils collected by Hatcher, Marsh determined that they belonged to sauropods, the group of long-necked herbivores that includes Diplodocus and Apatosaurus. More specifically, Marsh recognized that the Arundel sauropods were similar to “Morosaurus” (now called Camarasaurus) from Colorado. Today, the lineage of stocky, broad-nosed sauropods that includes Camarasaurus and its closest relatives are called macronarians. Unfortunately, by modern standards Marsh’s descriptions of P. altus and P. nanus are rudimentary in nature, and no distinguishing characteristics not common to all macronarian sauropods were offered.

Pleurocoelus elements. Image from NMNH Backyard Dinosaurs.

Pleurocoelus (or Astrodon?) fossils collected by Hatcher. Image from NMNH online exhibit Backyard Dinosaurs.

Contra Marsh, Hatcher suspected that there was only one sauropod in the Arundel Formation. P. altus and P. nanus were probably growth stages of one species, and the Astrodon teeth, now recognized as typical of macronarians, probably came from the same animal, as well. Since the International Code of Zoological Nomenclature decrees that the first published name given to a taxon has priority, Astrodon would take precedence over Pluerocoelus. Later, Charles Gilmore published a review of the Arundel fossils, in which he concurred with Hatcher that P. altus was a junior synonym of Astrodon, but retained P. nanus as a separate species.  

Then things started getting really complicated. While paleontologists were still debating how many sauropod species existed in the Arundel clay, Marsh and others had started naming lots of new species of Pluerocoelus. Fossils found in Texas, Oklahoma and even the U.K. were all thrown into the Pluerocoelus bucket, including P. montanusP. valdensisP. becklesii and P. suffosus. For much of the 20th century, Pluerocoelus was a classic wastebasket taxon, into which any and all sauropod fossils from early Cretaceous strata were casually thrown. Since the Pluerocoelus type specimens designated by Marsh were insufficient to define the taxon based on morphology, the name became little more than a temporal marker. Adding to the confusion, researchers continued to disagree over whether all these new Pluerocoelus species should be sunk into the earlier genus Astrodon.

In recent years, some progress has been made toward untangling this mess of early Cretaceous sauropods. There is a general consensus that fossils not found in Maryland’s Potomac Group differ substantially from the Arundel sauropods and should never have been referred to Pluerocoelus or Astrodon. New names have been proposed for the midwestern sauropods, including Astrophocaudia and Paluxysaurus. However, removing the non-Maryland fossils from the discussion merely returns us to the original set of problems: how many sauropods are represented in the Arundel clay, what were they like in life, and what should we call them?

Creating a coherent picture of Astrodon

Unfortunately, the answers to these questions depend on who you ask. The most thorough review of Arundel sauropods from the last decade was published by Kenneth Carpenter and Virginia Tidwell in 2005. Carpenter and Tidwell reaffirmed Hatcher’s conclusion that Pluerocoelus is synonymous with Astrodon, and that as the earliest published name, Astrodon has priority. This decision is apparently based only on the fact that the fossils came from the same stratum, however, since the Astrodon holotype cannot be compared to anything besides other teeth. For this reason, Michael D’Emic proposed in 2012 that the names Astrodon and Pluerocoelus are nomen dubia and should both be dropped entirely. Ultimately, neither solution is practical for identifying the sauropod fossils that continue to be collected from the Arundel Formation. Either we blindly refer any and all sauropod fossils to Astrodon, even though we lack a usable holotype, or we have no label available at all.  One solution would be to establish a new type specimen (called a neotype) for Astrodon, but this has yet to be done.

Both camarasaur and brachiosaur shaped Astrodon reconstructions are equally reasonable.

Both camarasaur and brachiosaur-shaped Astrodon reconstructions are reasonable. Artwork by Dmitry Bogdanov, via Wikipedia.

While many more sauropod fossils have been found in the Arundel clay since Hatcher’s 1887 expedition, we do not have enough material to fully elucidate what these animals looked like. Size estimates have varied enormously, from as little as 30 feet to as much as 80 feet in length. The assortment of fossil bones and teeth that have been found tell us we have a macronarian sauropod, and we can reconstruct its general shape based on more completely known relatives. However, macronarians were a fairly diverse bunch, ranging from the comparatively stocky camarasaurs to high-shouldered, elongate brachiosaurs. Carpenter and Tidwell describe the Arundel sauropod fossils, particularly the limb bones, as being fairly slender, but still more robust than those of Brachiosaurus. They do recognize, however, that nearly all known Arundel sauropod fossils come from juveniles, which may vary proportionally from adults. Because the precise affinities of Astrodon are unclear, artistic reconstructions vary substantially. The National Museum of Natural History’s Backyard Dinosaurs exhibit and website shows a camarasaur-shaped sauropod, while the life-sized sculpture at the Maryland Science Center is based on the brachiosaur Giraffatitan. At Dinosaur Park in Laurel, meanwhile, both versions are on display. More fossils, ideally cervical vertebrae or more complete adult material, are needed to clarify what the Arundel sauropod looked really like.

Teaching Astrodon

When I show people the teeth and partial bones attributed to Astrodon during public programs, I am almost always asked, “if that’s all you’ve found, how do you know what the whole animal looked like?”  As demonstrated by this post, it takes 1,700 words and counting to give a proper answer, which is too much for all but the most dedicated audiences. Nevertheless, to do anything less is to skip crucial caveats and information. Scientists are choosy about the words they use, filling explanations with “probablys” and “almost certainlys”, but they do so with good reason: when one’s job is to create and communicate knowledge, there is no room for ambiguity about what is and is not known. It is therefore just a bit dishonest to say that a large sauropod called Astrodon that was related to Brachiosaurus lived in Maryland, and yet I do so every week. How can I possibly sleep at night?

I’ll admit it can be difficult, but I get by because using one proviso-free name for the Maryland sauropod seems to be  informative and helpful to my audience. I only have people’s attention for so long, and I’d rather not spend that time on tangents about how Astrodon should really be called Pluerocoelus or why my use of either name is imprecise and problematic. I want visitors to walk away understanding how paleontologists assemble clues from sedimentary structures and anatomical comparisons to reconstruct ancient environments and their inhabitants. I’d like for visitors to practice making observations and drawing conclusions, and understand how paleontology is a meticulous science that can be relevant to their lives. “Paleontologists are weirdly obsessed with changing names” is not one of the most important things to know about paleontology.

Taxonomy, the science of naming and identifying living things, is unquestionably valuable. Biologists would be lost without the ability to differentiate among taxa. From my perspective, however, the public face of paleontology tends to overemphasize taxonomic debates in lieu of more informative discussions. There will always be somebody willing to argue whether Tarbosaurus bataar should be sunk into Tyrannosaurus, or to give incorrect explanations for why we lost “Brontosaurus.” In the end, though, these debates have more to do with people’s preferences than the actual biology of these animals. Astrodon may not be a diagnostic taxon in the strictest sense, but we need to call our fossils something, and taxonomic labels exist to be informative and useful. If asked, I’m always happy to provide the full story. But for the time being, Astrodon seems to be working just fine.

References

Carpenter, K. and Tidwell, V. 2005. Reassessment of the Early Cretaceous sauropod Astrodon johnstoni Leidy 1865 (Titanosauriformes). In Carpenter and Tidwell (eds.), Thunder-Lizards: The Sauropodomorph Dinosaurs. Bloomington, IA: Indiana University Press.

D’Emic M.D. 2012. Revision of the sauropod dinosaurs of the Lower Cretaceous Trinity Group, southern USA, with the description of a new genus. Journal of Systematic Paleontology, iFirst 2012, 1-20.

Gilmore, C.W. 1921. The fauna of the Arundel Formation of Maryland. Proceedings of the United States National Museum. 59: 581-594.

Kranz, P.M. Dinosaurs in Maryland. 1989. Published by Maryland Geological Survey, Department of Natural Resources, Educational Series No. 6.

Marsh, O.C. 1888. Notice of a New Genus of Sauropoda and Other New Dinosaurs from the Potomac Formation.

Please note that the usual disclaimer applies: views or opinions expressed here are mine, and do not reflect any institution with which I am affiliated.

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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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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.

References

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.

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