Category Archives: field work

Bully for Camarasaurus

Note: This post was written in 2014. It predates Emanuel Tschopp and colleagues’ 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 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 was 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 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 make 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’s reasonable to assume 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 cast 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 P 25112) 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 cast 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 an apatosaurine up to that point. 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.


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.


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.


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

Mount Making at MMFC14

This past week, I had the fantastic opportunity to be a part of the Mid-Mesozoic Field Conference. I can’t possibly offer enough praise to conference leaders ReBecca Hunt-Foster, Jim Kirkland, and John Foster for pulling off this amazingly informative journey across the Colorado plateau. Unfortunately, since we live in a world where it’s a bad idea to post images of fossil localities, and it’s downright toolish to share details about unpublished research, I won’t be posting a ton about the conference right now.

What I can share, however, are two stops we made that are especially relevant to this blog. The first is the Gaston Design workshop in Fruita, Colorado. Rob Gaston and his team specialize in casting and sculpting fossil replicas, and their mounted skeletons are on display all over North America, but especially at younger museums in the western interior. Gaston showed us how they mold, cast, and sculpt fossil replicas, a process that relies a great deal more on artistic and technical skill than fancy equipment.





This second set of photos is from the College of Eastern Utah Prehistoric Museum in Price, Utah. Ken Carpenter, the museum’s new director, has taken on the task of completely remounting the menagerie of Morrison dinosaurs in the center of the paleontology wing (some photos of the old mounts here). The original AllosaurusCamptosaurus and Stegosaurus mounts from the late 1980s suffered from an unfortunate case of the tail-drags, and the Camarasaurus had previously been relegated to a death pose. Carpenter’s new mounts, which combine original fossils with new and old reconstructed bones, are much livelier. The stated goal of the project is to encourage visitors to imagine what it would be like to encounter these animals in life. What’s really awesome, though, is that the mounts are being built right in the exhibit, so that visitors can see the progress and the tools and techniques used to build these displays. At present, Allosaurus and Camptosaurus are finished, work on Stegosaurus is underway, and the Camarasaurus skeleton is laid out in pieces.




Sorry to post such a short tease of the awesome stuff we saw at the conference. My head is absolutely packed with information and ideas, so hopefully there will be opportunities to share more soon!

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Filed under dinosaurs, field work, fossil mounts, museums, paleoart

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.


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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Filed under citizen science, Dinosaur Park, dinosaurs, field work, history of science, reviews, sauropods, systematics

Extinct Monsters: Brachyceratops

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

Most of the mounted dinosaur skeletons at the National Museum of Natural History (NMNH) represent taxa that are well-known to casual paleontology enthusiasts. But nestled amongst household names like Triceratops, Stegosaurus and Diplodocus is an easily-overlooked horned dinosaur that was historically called Brachyceratops montanensis (it’s currently labeled Styracosaurus sp). Tucked away in a glass case behind the giant Triceratops, this pocket-sized ceratopsian may not be the most spectacular display in the exhibit, but it is nevertheless an important one for the Museum. Discovered in 1913 by the Smithsonian’s own Curator of Fossil Reptiles Charles Gilmore, Brachyceratops represents one of only a few dinosaur species excavated, prepared, described and exhibited entirely in-house at NMNH. It is therefore unfortunate that modern researchers have banished the name Brachyceratops to the realm of taxonomic obscurity. What’s more, the days of the Brachyceratops mount, on exhibit since 1922, are numbered: when the NMNH paleontology halls closed for renovation in April 2014, this specimen was be retired to the collections, and is not planned for inclusion when the exhibit reopens in 2019.

The Brachyceratops mount today. Photo by the author.

The Brachyceratops mount today. Photo by the author.

During his tenure at NMNH, Gilmore was an inexhaustibly productive writer, publishing at least 170 scientific articles, including numerous important descriptions and reassessments of fossils discovered by O.C. Marsh’s teams in the 19th century. However, Gilmore was much happier studying fossils in his lab than excavating new finds in the field, taking part in a scant 16 NMNH-sponsored field expeditions over the course of his career. A 1913 trip to the Cretaceous Two Medicine Formation in Northeast Montana was therefore unusual for Gilmore. He was following in the footsteps of Eugene Stebinger of the US Geological Survey, who had reported the previous year that the region was only minimally explored but clearly awash in vertebrate fossils.

On this inaugural fossil prospecting trip, Gilmore’s team located abundant remains of fish, small reptiles and dinosaurs, especially hadrosaurs and ankylosaurs. The most notable find, however, was a small bone bed (about six feet square) of ceratopsian fossils, representing at least five individuals. Gilmore described this find in a 1917 monograph, naming the dinosaur Brachyceratops montanensis. Today we know that ceratopsians were quite diverse, particularly during the Campanian, but in the early 20th century the true extent of the group was only just being revealed. Still, it was clear to Gilmore that at an estimated six feet in length, Brachyceratops was an unusually small ceratopsian. He proposed that it may have fed on different plants or occupied a different niche than larger contemporaries like Centrosaurus and Styracosaurus.

pretty art

Reconstruction of Brachyceratops holotype skull. Plate from Gilmore 1917.

In 1917, most of the dinosaur mounts on display at NMNH came from fossils collected by Marsh for the US Geological Survey, and many represented species also on display in New York, Pittsburgh and New Haven. Accordingly, Gilmore was doubtlessly enthused by the prospect of displaying a dinosaur exclusive to Smithsonian. He awarded the task of creating a Brachyceratops mount to preparator Norman Boss, who would spend 345 working days on the project. Of the five individuals found in Montana, USNM 7953 was selected as the basis for the mount because it was the most complete, with the sacrum, pelvis, femora and complete set of caudal vertebrae found articulated in situ. Helpfully, Gilmore published a list of precisely which parts of the mount came from which individual specimen (see below). This was a marked contrast from some of his contemporaries at other museums, who would not bother to record such information, or even actively obscure how many disparate specimens they were using to build their mounts.

Gilmore's helpful list

A helpful breakdown of the Brachyceratops mount from Gilmore 1922.

Boss based his restoration of Brachyceratops closely on the complete, articulated Monoclonius (=Centrosaurus) specimen (AMNH 5351) discovered by Barnum Brown in 1914. In particular, Boss replicated the angle of the scapulae and the number of vertebrae (22) on the American Museum of Natural History skeleton. Missing bones and portions thereof were sculpted in plaster, easily recognized by their solid color and smooth texture. Just as Gilmore and Boss had done with their 1905 Triceratops mount, the Brachyceratops was given strongly flexed elbows. According to Gilmore, a very large olecranon process on the ulna would have forced all ceratopsians into this somewhat awkward stance. Of particular note is the restoration of the skull, which was found shattered into dozens of pieces, many smaller than one inch. A close look at the specimen reveals how Boss painstakingly reassembled these fragments. Unfortunately, this is difficult in the exhibit hall because the mount is posed with the side of the skull that is mostly plaster facing visitors.

Norman Boss Brachyceratops courtesy Smithsonian archives

Norman Boss puts the finishing touches on the Brachyceratops mount. Photo courtesy of the Smithsonian Archives.

The completed Brachyceratops mount was placed on exhibit in 1922, on the same pedestal in the Hall of Extinct Monsters as the Triceratops. The substrate beneath the mount was colored and textured to match the Two Medicine Formation sandstone in which the fossils were found. Gilmore also prepared one of his charming models of Brachyceratops, mirroring the pose of the mount, but it is unclear whether it was ever exhibited.

woo triceratops

Brachyceratops on exhibit with Triceratops. Plate from Gilmore 1922.

The Brachyceratops has remained on view through each subsequent renovation of the fossil halls, always placed close to Triceratops. This close association has prompted many visitors to mistake the diminutive Brachyceratops for a baby Triceratops, and in fact these visitors are on the right track. While Gilmore always described Brachyceratops as an unusually small but full-grown ceratopsian, Scott Sampson and colleagues confirmed in 1997 that all five specimens were juveniles. A century’s worth of new fossil discoveries has provided modern paleontologists with a thorough understanding of ceratopsian ontogeny, and characteristics like the unfused nasal horn clearly mark the mounted Brachyceratops as a young animal. Unfortunately, Gilmore’s Brachyceratops specimens lack any good diagnostic features that could link it to an adult form. According to Andrew McDonald, the most likely candidate is Rubeosaurus ovatus, which was, incidentally, discovered by Gilmore on a 1922 repeat trip to the Two Medicine site. 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 mounts to include in a renovated gallery. 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. It’s not all bad, though. Taking these fossils off exhibit will make them more accessible to researchers, and allow them to be closely examined in all aspects for the first time in decades. Perhaps one day soon we will have a clearer idea of the identity of one of Gilmore’s great finds.


Gilmore, C.W. (1917). Brachyceratops, a Ceratopsian Dinosaur from the Two Medicine Formation of Montana, with Notes on Associated Fossil Reptiles. Washington, DC: US Geological Survey.

Gilmore, C.W. (1922). The Smallest Known Horned Dinosaur, Brachyceratops. Proceedings of the US National Museum 63:2424.

Gilmore, C.W. (1930). On Dinosaurian Reptiles from the Two Medicine Formation of Montana. Proceedings of the US National Museum 77:2839.

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 dinosaurs, exhibits, Extinct Monsters, field work, fossil mounts, history of science, marginocephalians, museums, NMNH, reptiles

First Full-Sized Dinosaurs: From Crystal Palace to Hadrosaurus

Last time, we covered how Albert Koch turned a tidy profit with his less-than-accurate fossil mounts, leading credible paleontologists to avoid involvement with full-sized reconstructions of extinct animals for much of the 19th century. With the exceptions of Juan Bautista Bru’s ground sloth and Charles Peale’s mastodon, all the fossil mounts that had been created thus far were horrendously inaccurate chimeras assembled by often disreputable showmen. Serious scientists were already struggling to disassociate themselves from these sensationalized displays of imaginary monsters, so naturally they avoided degrading their work further by participating in such frivolous spectacle.

The prevailing negative attitude toward fossil mounts among academics would begin to shift in 1868, when paleontologist Joseph Leidy and artist Benjamin Waterhouse Hawkins collaborated on a mount of Hadrosaurus, the first dinosaur to be scientifically described in America and the first dinosaur to be mounted in the world. While prehistoric animals were well known by the mid-19th century, the Hadrosaurus was so bizarre, so utterly unlike anything alive today, that it truly opened people’s eyes to the unexplored depths of the Earth’s primordial history. I have written about the Hadrosaurus mount before, but its creation was such a landmark event in the history of paleontology and particularly the public understanding of prehistory that it deserves to be contextualized more thoroughly.

Discovering Dinosaurs in Britain

In the early 1800s, American fossil hunters were busy poring over the bones mammoths, mastodons and other mammals. Across the Atlantic, however, it was all about reptiles. Scholars were pulling together the first cohesive history of life on earth, and Georges Cuvier was among the first to recognize distinct periods in which different sorts of creatures were dominant. There had been an Age of Mammals in the relatively recent past during which extinct animals were not so different from modern megafauna, but it was preceded by an Age of Reptiles, populated by giant-sized relatives of modern lizards and crocodilians. The marine ichthyosaurs and plesiosaurs unearthed by Mary Anning on the English coast were the first denizens of this era to be thoroughly studied, but they were soon followed by discoveries of terrestrial creatures. In 1824, geologist William Buckland received a partial jaw and a handful of postcranial bones found in the Oxfordshire shale. Recognizing the remains as those of a reptile, Buckland named the creature Megalosaurus, making it the first scientifically described non-avian dinosaur (honoring the unspoken agreement to ignore “Scrotum humanum”).

The partial jaw of Megalosaurus, the first named dinosaur.

The partial jaw of Megalosaurus, the first named dinosaur.

Of course, the word “dinosaur” did not yet exist. As covered by virtually every text ever written on paleontological history, it was anatomist Richard Owen who formally defined Dinosauria in 1842 as a distinct biological group. Owen defined dinosaurs based on anatomical characteristics shared by Megalosaurus and two other recently discovered prehistoric reptiles, Iguanodon and Hylaeosaurus (fatefully, and somewhat arbitrarily, he excluded pterosaurs and doomed paleontologists and educators to forever reminding people that pterodactyls are not dinosaurs). In addition to being an extremely prolific author (he wrote more than 600 papers in his lifetime), Owen was a talented publicist and quite probably knew what he was unleashing. The widely publicized formal definition of dinosaurs, accompanied by displays of unarticulated fossils at the Glasgow Museum, was akin to announcing that dragons were real. By giving dinosaurs their name, Owen created an icon for the prehistoric past that the public could not ignore.

“Dinosaur” soon became the word of the day in Victorian England. Looking to capitalize on this enthusiasm for paleontology, the Crystal Palace Company approached Owen in 1852 to oversee the creation of an unprecedented new exhibit. The company was building a park in the London suburb of Sydenham, meant to be a permanent home for the magnificent Crystal Palace, which had been built the previous year for the Great International Exhibition of the Works and Industry of All Nations. Concerned that the palace would not draw visitors to the park on its own, the Crystal Palace Company commissioned Owen and scientific illustrator Benjamin Waterhouse Hawkins to create a set of life-sized sculptures of dinosaurs and other prehistoric creatures, the first of their kind in the world. The sculptures were a tremendous undertaking: the Iguanodon, for instance, was supported by four 9-foot iron columns, and its body was built up with brick, tile and cement. Hawkins then sculpted its outer skin from more than 30 tons of clay. All told, more than a dozen animals were built, including Megalosaurus, Iguanodon, Hylaeosaurus and an assortment of marine reptiles and mammals.

The Crystal Palace dinosaurs under construction in Hawkin's studio.

The Crystal Palace dinosaurs under construction in Hawkin’s studio.

Queen Victoria herself presided over the opening ceremony of Crystal Palace Park in 1854, which was attended by 40,000 people. This was an important milestone because up until that point, only the broadest revelations in geology and paleontology made it out of the academic sphere. But as Hawkins himself put it, the Crystal Palace dinosaurs “might be properly described as one vast and combined experiment of visual education” (Hawkins 1853, 219). The general public could see firsthand the discoveries and conclusions of the most brilliant scientists of their age, in a format that could not only be readily understood and appreciated, but experienced. Full-sized reconstructions of prehistoric animals, including fossil mounts, continue to be built today for precisely this reason.

Recently restored Iguanodon sculptures. Wikimedia Commons.

Recently restored Iguanodon sculptures at Crystal Palace Park. Source

While the Crystal Palace dinosaurs are important historic artifacts and beautiful works of art in their own right, they have not aged well as accurate reconstructions. Owen only had the scrappiest of dinosaur fossils to work with, enough to conclude that they were reptiles and that they were big but not much else. As a result, the Megalosaurus and Iguanodon sculptures look like rotund lizards, as though a monitor lizard or iguana gained the mass and proportions of an elephant. By modern standards, these beasts look pretty ridiculous as representations of dinosaurs, but they were quite reasonable given what was known at the time, at least for a few years.

Dinosaurs of the Jersey Shore

And so at last Hadrosaurus enters the story. Just four years after the unveiling of the Crystal Palace sculptures, the first American dinosaur was found on a farm near Haddonfield, New Jersey (dinosaur footprints and teeth had been found earlier, but their affinity with the European reptiles was not recognized until later). William Foulke, a lawyer and geology enthusiast affiliated with the Philadelphia-based Academy of Natural Sciences, was at his winter home in Haddonfield when he paid a visit to his neighbor, John Hopkins. Hopkins told Foulke that he occasionally found large fossils on his land, which he generally gave away to interested friends and family members. With Hopkins’ permission, Foulke searched the site where the fossils had been found with the assistance of paleontology and anatomy specialist Joseph Leidy. Also a member of the Academy of Natural Sciences, Leidy is considered the founder of American paleontology and during the mid-1800s, he was the preeminent expert on the subject. At the Haddonfield site, Foulke and Leidy uncovered approximately a third of a dinosaur skeleton, including two  nearly complete limbs, 28 vertebrae, a partial pelvis, scattered teeth and two jaw fragments.

All known Hadrosaurus fossils, presently on display at the Academy of Natural Sciences.

All known Hadrosaurus fossils, presently on display at the Academy of Natural Sciences.

Now in possession of the most complete dinosaur skeleton yet found, Leidy began studying the fossils of what he would name Hadrosaurus foulkii (Foulke’s bulky lizard) in Philadelphia. The teeth in particular told Leidy that Hadrosaurus was similar to the European Iguanodon. Like IguanodonHadrosaurus was plainly an herbivore, and for reasons left unspecified Leidy surmised that it was amphibious, spending most of its time in freshwater marshes. Leidy noted that Hadrosaurus was a leaner and more gracile animal than Owen’s Crystal Palace reconstructions, but he was particularly interested in “the enormous disproportion between the fore and hind parts of the skeleton” (Leidy 1865). Given the large hindlimb and small forelimb, Leidy reasoned that Hadrosaurus was a habitual biped, and likened its posture to a kangaroo, with an upward-angled trunk and dragging tail. As such, we can credit Leidy for first envisioning the classic Godzilla pose for dinosaurs, which has been known to be inaccurate for decades but remains deeply ingrained in the public psyche.

Although the new information gleaned from Hadrosaurus made it clear that the Crystal Palace sculptures were hopelessly inaccurate, Leidy had been impressed by the Sydenham display and wanted to create a similar public attraction in the United States. Leidy invited Hawkins to prepare a new set of prehistoric animal sculptures for an exhibit in New York’s Central Park. Hawkins set up an on-site studio and began constructing a life-sized Hadrosaurus, in addition to a mastodon, a ground sloth and Laelaps, another New Jersey dinosaur. Unfortunately, Hawkins’ shop was destroyed one night by vandals, apparently working for corrupt politicians. What remained of the sculptures was buried in Central Park and the exhibit was cancelled.

Edit 4/20/2017: Leidy was not actually involved in planning the ill-fated Central Park display. Thanks to Raymond Rye for the tip!

The “Bulky Lizard” Mount

Instead of abandoning the project entirely, Hawkins and Leidy redirected the resources they had already prepared for the Central Park exhibit into a display at the Academy of Natural Sciences museum in Philadelphia. Leidy decided he wanted a mounted skeleton of Hadrosaurus, rather than a fully fleshed model as was originally planned. Such a display had not appeared in a credible museum since Charles Peale created his mastodon mount, but if anybody could get a fossil mount to be taken seriously, it was Leidy.

With only a partial Hadrosaurus skeleton to work with, Hawkins had to sculpt many of the bones from scratch, in the process inventing many of the mounting techniques that are still in use nearly a century and a half later. For instance, Hawkins created mirrored duplicates of the left limb bones for use on the animal’s right side, and reconstructed best-guess stand-ins for the skull, scapulae and much of the spinal column using modern animals as reference. Based on photographs like the one below, it appears that portions of the vertebral column were cast as large blocks, rather than individual vertebrae. The mount  was supported by a shaped metal rod running through the vertebrae, as well as a single vertical pole extending from the floor to the base of the neck. In fact, very little of the armature appears to have been externally visible, suggesting that making the skeleton as aesthetically clean as possible was a priority.

Hawkin's studio

Hadrosaurus under construction in Hawkins’ studio. Note the flightless bird mounts used for reference. From Carpenter et al. 1994.

The Hadrosaurus mount had a few eccentricities that are worth noting. First, the mount has seven cervical vertebrae, which is characteristic of mammals, not reptiles. Likewise, the scapulae and pelvis are also quite mammal-like. Hawkins was apparently using a kangaroo skeleton as reference in his studio, and it is plausible that this was the source of these mistakes. In addition, Hawkins had virtually no cranial material to work with (despite several repeat visits to the Haddonfield site by Academy members searching for the skull), so he had to make something up. He ended up basing the his sculpted skull on an iguana, one of the few exclusively herbivorous reptiles living today. Although fossils of Hadrosaurus relatives would later show that this was completely off the mark, it was very reasonable given what was known at the time.

The Hadrosaurus mount was unveiled at the Academy of Natural Sciences musuem in 1868, and the response was overwhelming. The typical annual attendance of 30,000 patrons more than doubled that year to 66,000, and the year after that saw more than 100,000 visitors. Traffic levels were so high that the Academy had to decrease the number of days it was open and enforce limits on daily attendance in order to prevent damage to the rest of the collection. Soon, the Academy was forced to relocate to a new, larger building in downtown Philadelphia, which it still occupies today.

The audience for the Hadrosaurus mount was expanded greatly in the 1870s by three plaster copies of the skeleton, which were sent to Princeton University in New Jersey, the Smithsonian Institution in Washington, DC and the Royal Scottish Museum in Edinburgh (the first dinosaur mount displayed in Europe). The Smithsonian copy had a particularly mobile existence: it was first displayed in  the castle on the south side of the National Mall, moved to the dedicated paleontology display in the Arts and Industries Building around 1890, and finally traded to the Field Museum in Chicago later in the decade. In Chicago, the Hadrosaurus was displayed in a spacious gallery alongside mounts of Megaloceros and Uintatherium, and it is in this context that the best surviving photographs of the Hadrosaurus mount were taken. Sadly, by the early 1900s all three casts had been destroyed or discarded by their host institutions, since they had either deteriorated badly or were deemed too inaccurate for continued display. The original Philadelphia mount was also dismantled, although the Hadrosaurus fossils are still at the Academy.

Hadrosaurus cast on display at the Field Museum. Field Museum Photo Archives.

Hadrosaurus cast on display at the Field Museum. Field Museum Photo Archives.

Why was the Hadrosaurus mount such a big deal? For one thing, it was different from previous fossil mounts in that it was the product of the best scientific research of the day. This was not the work of a traveling showman but a display created by the preeminent scientific society of the era, with all the mystique and prestige that came with it. Most importantly, however, the Hadrosaurus mount presented the first ever opportunity to stand in the presence of a dinosaur. By the mid-19th century, western civilization had had ample opportunity to come to terms with the fact that organisms could become extinct, but for the most part the fossils on display were similar to familiar animals like horses, elephants and deer. The Hadrosaurus, however, was virtually incomparable to anything alive today. It was a monster from a primordial world, incontrovertible evidence that the Earth had once been a very different place. By comparison, the Crystal Palace sculptures were essentially oversized lizards, and therefore fairly relateable.  The Hadrosaurus was the real turning point, the moment the public got their first glimpse into the depths of prehistory. For 15 years, the Hadrosaurus was the only real dinosaur on display anywhere in the world, so it is no wonder that people flocked to see it.

Of course, the Hadrosaurus was only the beginning of the torrent of dinosaur fossils that would be unearthed in the late 19th century. It would prove to be but a hint at the amazing diversity and scale of the dinosaurs that would be revealed in the American west, as well as the scores of fossil mounts that would soon spring up in museums.


Carpenter, K., Madsen, J.H. and Lewis, L. (1994). “Mounting of Fossil Vertebrate Skeletons.” In Vertebrate Paleontological Techniques, Vol. 1. Cambridge, UK: Cambridge University Press.

Leidy, J. (1865). “Cretaceous Reptiles of the United States.” Smithsonian Contributions to Knowledge. 14: 1-102. 

Waterhouse Hawkins, B. (1853). “On Visual Education as Applied to Geology.” Journal of the Society of Arts. 2: 444-449.


Filed under anatomy, dinosaurs, field work, fossil mounts, history of science, museums, ornithopods, paleoart, reptiles

The Artist in His Museum: Peale’s Mastodon

In 1806, naturalist and painter Charles Wilson Peale assembled in Philadelphia the skeleton of a mastodon (Mammut americanum).While Peale’s mastodon was not the first fully assembled fossil animal put on display, it was assuredly the first display of this type to capture widespread public attention, particularly in the United States. What’s more, the mastodon became an important symbol for the untold natural wonders of the American continent, which was still largely unexplored (by European colonists) at the beginning of the 19th century. Finally, Peale’s mastodon made clear to the public one of the most important principles of modern biology: the idea that organisms can become extinct.

The Peale Museum mastodon, as illustrated by Charles Peale's son, Rembrandt. The Peale Museum mastodon, as illustrated by Charles Peale’s son, Rembrandt.

An extinct giant

The story of the mastodon mount actually began a full century before the 1806 debut. In 1705, a farmer in Claverack, New York found an enormous tooth that had eroded out of a hillside. The farmer traded the tooth to a local politician, and it eventually made it its way into the hands of New York’s colonial governor, Edward Hyde, 3rd Earl of Clarendon. Hyde in turn sent the tooth to London, describing it as a remnant of an antediluvian giant. As word of the remains of a giant spread, other Americans soon began reporting similar finds. Throughout the colonies, giant bones, teeth, and tusks began to be uncovered. While early reports called these fossils the remains of “incognitum,” or “the unknown,” naturalists caught on reasonably quickly that these were not the bones of giant men but of elephant-like creatures.

At this point a brief digression on etymology and taxonomy is required. For most of the 19th century, the American fossil elephants were invariably called “mahmot” or “mammoth.” This was an Anglicization of the Old Vogul term maimanto (meaning earth-horn), which referred to giant tusks occasionally found in Siberia. It is unclear, however, who first made the correct connection between the frozen mammoths of Siberia and the American fossil skeletons. Credit for adopting “mammoth” as a synonym for “big” goes to Thomas Jefferson, who was fascinated by paleontology and the mammoth fossils in particular.

It was not until 1817 that French anatomist Georges Cuvier recognized that there were at least two types of extinct American proboscideans: the taller mammoths and stockier mastodons. Unequivocally demonstrating the staggering repression of the Victorian era, Cuvier coined the name “mastodon,” meaning nipple tooth, because apparently he thought the animal’s most distinguishing feature was that its teeth looked like breasts.

Boobs? Couvier, you poor bastard. Cuvier, you poor bastard.

The American elephantine fossils raised difficult questions for naturalists. The fossils clearly belonged to animals that had never been seen alive, which meant that the entire species must have died out. This concept of extinction was new to science, and it challenged the biblically-inspired presumption that all species had originated in a single creation event. Cuvier was a leader in the 19th century scientific movement known as catastrophism–the idea that extinctions were the result of periodic disasters, such as floods. While Cuvier himself rejected the idea that populations of organisms could avoid extinction by adapting and changing, his work on extinction would prove important when Charles Darwin worked out the process of evolution several decades later.

Unearthing the mastodon

In 1789, Nicholas Collin of the American Philosophical Society proposed a search for a complete mammoth skeleton, in order to resolve the animal’s identity and the question of its extinction once and for all. Collin’s call was answered by Charles Wilson Peale, founder of America’s first modern museum. Peale is best known today as a portrait artist during the American Revolution, but he was also the founder of the Peale Museum in Philadelphia. Although semi-formal collections of interesting natural specimens had existed before, Peale uniquely fashioned his institution as a space for public education, rather than a private vanity project. On the second floor of Philadelphia’s Independence Hall, Peale arranged displays of mammals, birds, and plants in a scala naturae, which was the contemporary understanding of natural order. Peale intended the museum to be a public resource that would improve visitors’ moral character through lessons in science, as was made clear by the slogan printed on every ticket, “the birds and beasts will teach thee.”

In 1799, a farmer named John Masten reported that he had found bones of “an animal of uncommon magnitude” on his land outside Newburgh, New York. Masten gathered a large party of friends and neighbors to help excavate the find. This proved to be a little too much fun: the crowd eventually descended into alcohol-fueled chaos, and many of the fossils were destroyed. Nevertheless, Peale decided to pay Masten a visit, with the hope of securing mammoth fossils for his museum. Peale ended up paying Masten $200 for the surviving fossils, plus another $100 for the right to search his land for more remains. Peale returned to Masten’s farm with a better-organized crew and $500 in additional funding from the American Philosophical Society. The ensuing excavation is the subject of Peale’s 1806 painting, The Exhumation of the Mastodon, shown below.

“The Exhumation of the Mastodon” by Charles Peale, 1806.

Although highly dramatized, The Exhumation of the Mastodon provides the best available record of the event. Since the pit where Masten first found the bones had filled with water, Peale oversaw the construction of a huge wooden wheel, which drove a conveyor belt hauling buckets of water out of the work site. Peale himself can be seen on the right, presiding over his small army of excavators. The well-publicized project eventually uncovered most of a mastodon. Exploring a few nearby farms, Peale’s workers eventually accumulated enough material to build a complete skeleton, most notably a mandible found on another farm down the road. In what was either showmanship or genuine confusion regarding the diets of elephants, Peale said of the find, “Gracious God, what a jaw! How many animals must have been crushed beneath it!” (quoted in Simpson 1942, 159).

The mastodon on exhibit

Once the mastodon skeleton had been transported to Philadelphia, the process of building the mount fell upon Peale’s son Rembrandt and Moses Williams, an enslaved man who worked for the Peales. It took three months to articulate the skeleton, although sadly the details of how it was mounted on its armature are lost to history. Initiating a practice that would become necessity for most fossil mounts in years to come, Rembrant filled in missing parts of the mastodon skeleton (the top of the cranium and the tail) with sculpted elements. In addition, wooden discs were placed between vertebrae, slightly exaggerating the mount’s total length.

The completed mastodon mount was unveiled in 1802, in the main hall of the American Philosophical Society. Shortly thereafter, it was moved to the Peale Museum at Independence Hall. For 50 cents (plus regular admission), the visiting public could marvel at the creature Peale touted as “the first of American animals” and “the largest of terrestrial beings.” The mastodon (still being called a mammoth at that time) was a sensation, stirring up fascination with natural science, the prehistoric past, and no small amount of ours-is-bigger-than-yours patriotism in the young United States. In 1822, Peale would commemorate the unveiling of the mastodon with his self portrait, The Artist in His Museum. Ever the showman, Peale ensured that the skeleton in his painting is only barely visible below the rising curtain.

“The Artist in His Museum” by Charles Peale, 1822.

After Peale’s death in 1827 his museum floundered, and was eventually reduced from a meritorious educational institution into a circus of cheap spectacle. It shut down for good in 1848, and the mastodon (by then one of many similar mounts) was put up for auction. There are several conflicting accounts of what became of the mount, including the suggestion that it was destroyed in a fire, but in fact Peale’s mastodon has survived to the present day. Johann Jakob Kaup purchased the skeleton for the Landesmuseum in Durmstadt, Germany, and it has remained on display there ever since.

Germany Peale’s mastodon survives in Durmstadt, Germany. Source

Peale’s mastodon left an unmistakable legacy for both paleontology and public education. Today, the public conception of prehistory is inseparably connected to the image of towering mounted skeletons in museum halls. But fossils do not come out of the ground bolted to steel armatures, so it is largely thanks to Peale that mounts have become the most enduring means of sharing paleontology with the public.


Carpenter, K., Madsen, J.H. and Lewis, L. (1994). Mounting of Fossil Vertebrate Skeletons. Vertebrate Paleontological Techniques, Vol. 1. Cambridge, UK: Cambridge University Press.

Connriff, R. (2010). Mammoths and Mastodons: All American Monsters. Smithsonian Magazine.

Semonin, P. (2000). American Monster: How the Nation’s First Prehistoric Creature Became a Symbol of National Identity. New York, NY: New York University Press.

Simpson, G.G. (1942). The Beginnings of Vertebrate Paleontology in North Ameirca. Proceedings of the American Philosophical Society 86:130-188.


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

D.C. area fossils on WAMU

Matt Carrano of the National Museum of Natural History, Alan Dooley of the Virginia Museum of Natural History and Dave Hacker of Maryland’s Dinosaur Park were interviewed on the Kojo Nnamdi show this afternoon. You can listen to the stream here. Topics covered include the 2019 re-opening of the NMNH fossil halls, local Cretaceous and Miocene paleoenvironments, the harm caused by commercial fossil collecting and the Discovery Channel C. megalodon travesty. Since I work for the MNCPPC at Dinosaur Park and have been involved with NMNH in the past, this is all quite near and dear to me. If you’ve got 20-30 minutes, it’s well worth a listen!

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Filed under Dinosaur Park, dinosaurs, field work, NMNH

A Triceratops for Lawrence

In an earlier post, I described how the Smithsonian’s Triceratops was the first free-standing mount of this animal ever created, and the eccentricities of its proportions and posture would define how the species would be depicted in artwork and other reconstructions for the better part of a century. I should have clarified, however, that this was not the first time Triceratops fossils were put on public exhibit. That honor goes to the University of Kansas Natural History Museum, which was founded in 1864 and is still operational today.

Among the Museum’s basement paleontology exhibits is a case of dinosaur fossils that has literally gone unchanged since the 1950s. Although this time capsule of mid-century museum design is of some historical interest, it would be nice if those sauropod limb bones weren’t labeled “Brontosaurus” (to be clear, the whole museum doesn’t look like this, the staff has been slowly but surely modernizing the exhibits). Of particular importance is the Triceratops skull (specimen 422) on the left side of the case. While there is no historical information on its label, this specimen has been with the museum for over 115 years, having been unearthed and put on display only six years after O.C. Marsh first named and described Triceratops.

The dinosaur case at the KU Natural History Museum, untouched since the 1950s.

The dinosaur case at the KU Natural History Museum, untouched since the 1950s.

The story of the KU Triceratops is not well-known, although it is the subject of the somewhat hard-to-find book (neither the Museum nor the KU library has a copy) A Triceratops Hunt in Pioneer Wyoming. In the summer of 1895, a team from the University ventured into the frontier lands of of eastern Wyoming with the explicit goal of finding a Triceratops for display at the young Natural History Museum. The team was led by Samuel Wendell Williston, founder of the University’s geology department. Although Williston’s specialty was entomology, he had previously worked under Marsh at Yale and was well-acquainted with the plethora of dinosaurs on which his mentor had published. Also on the expedition were KU Regent James Polk Sams, and two individuals whose names are quite familiar to anyone with an interest in the history of paleontology, Barnum Brown and Elmer Riggs. Brown would, of course, go on to be the star fossil hunter at the American Museum of Natural History, while Riggs would become a curator at the Field Museum of Natural History. In 1895, however, both were students, and not especially interested in fossil collecting or paleontology. 

The team found the Triceratops they were looking for on July 9, near the confluence of Lightning and Lance Creeks. By July 22, the skull was fully excavated and crated for a journey by train back to Lawrence. The fossil apparently garnered a fair amount of attention on the journey; while Triceratops is well known today, in 1895 few had any idea that animals such as this had ever walked the Earth. And yet, here was clear, physical evidence of an extinct animal like nothing alive in the modern world, and it would soon be displayed for all to see in the University of Kansas Museum.

Triceratops skull retrieved by the 1895 Wyoming expedition.

Triceratops skull retrieved by the 1895 Wyoming expedition.

The 1895 expedition was not tremendously productive scientifically, the fossils found that summer resulting in only three short papers. However, the journey, and the Triceratops skull that was brought back, did end up being quite important for paleontology. The expedition inspired Brown and Riggs to pursue careers in paleontology, and as Brinkman and colleagues write in Triceratops Hunt in Pioneer Wyoming, “they would hunt bones for the rest of their lives, to the great benefit of science, and might never have done so had not circumstances landed them in the circle of Williston’s influence in the summer of 1895.”

Furthermore, by setting out with the clear goal to find a dinosaur for display, the University of Kansas team were trailblazers in a movement that would lead to the inseparable connection between dinosaurs and museums in popular culture today. In the first decade of the 20th century, newly burgeoning large urban museums openly competed to find and display the largest and most spectacular dinosaurs. Exhibits like the AMNH Brontosaurus, the Carnegie Museum of Natural History Diplodocus and, of course, the Smithsonian Triceratops brought millions of Americans into museums, ensuring that to this day, when we think of museums, we think of dinosaur skeletons (and vice versa). In spite of the somewhat dingy basement display it currently finds itself in, the University of Kansas Triceratops was an early trendsetter and a profound example of the intersection of science and history.


Kohl, M.F., Martin, L.D. and Brinkman, P., eds. (2004). Triceratops Hunt in Pioneer Wyoming: The Journals of Barnum Brown and J.P. Sams. Glendoo, WY: High Plains Press.


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

Extinct Monsters: The Marsh Dinosaurs, Part II

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

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

The Ceratosaurus

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

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

Ceratosaurus. Photo by the author.

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

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

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

The Camptosaurus

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

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

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

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

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

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

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

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

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

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

The Stegosaurus

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

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


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

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

Cast of Stegosaurus and Camptosaurus. Photo by the author.

Casts of Stegosaurus and Camptosaurus. Photo by the author.

Roadkill stego

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

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

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


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

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

Jabo, S. 2012. Personal communication.

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Filed under collections, dinosaurs, exhibits, Extinct Monsters, field work, fossil mounts, history of science, museums, NMNH, ornithopods, reptiles, theropods, thyreophorans

Extinct Monsters: Ice Age Giants

Click here to start the NMNH series from the beginning.

The old fossil mammal exhibits at the National Museum of Natural History were notable for their sheer diversity. From rabbits to elephants and from bats to whales, virtually every major group of North American mammals, particularly eutherian (placental) mammals, was represented. By my count, there were no less than 48 mounted mammal skeletons on display (not including individual skulls and other parts) in 2014, arranged by time period and distributed across three sizable halls.

The comprehensive nature of these exhibits was largely thanks to C.L. Gazin, head curator of the Division of Vertebrate Paleontology in the 1950s and 60s. During the modernization of the fossil halls in the early 1960s, Gazin focused his efforts on assembling a complete narrative of Cenozoic mammal evolution. The six-part exhibit debuted in 1961 in Hall 5, and was relocated two decades later to Hall 3. Gazin also initiated the construction of the adjacent Ice Age exhibit, although it would not be permanently opened to the public until 1974.

Now that the fossil halls are being renovated, NMNH staff face the enormous task of disassembling and restoring the dozens of historic mammal skeletons. Many will return when the exhibit reopens in 2019, but others may be retired to the collections if they are deemed too fragile for continued display, or if they are not illustrative of the story being told in the new exhibit.

The Megaloceros

This Megaloceros

This Megaloceros has the distinction of being the Smithsonian’s first mounted skeleton composed of original fossils. Photo by the author.

The Smithsonian’s first mounted fossil skeletons went on display in 1871 in the building colloquially called “the castle.” The exhibit included plaster casts of the ground sloth Megatherium, the tortoise Colossochelys and the glyptodont Scistopleurum, all made from originals at the British Museum. The following year saw the addition of the giant deer Megaloceros (USNM V 7051) — the Smithsonian’s first mounted skeleton composed of original fossils. The Smithsonian purchased this complete Megaloceros, which was uncovered in an Irish peat bog, from Philadelphia-based antiques dealer Thomas and Sons. The mount was assembled by none other than Benjamin Waterhouse Hawkins, the sculptor who created the famous Crystal Palace dinosaurs.

Note basilo

Megaloceros in the southeast court of the Arts and Industries building, circa 1896. The British Museum Megatherium cast can be seen on the left. Source

When construction of the original United States National Museum (what is now called the Arts and Industries Building) was completed in 1881, all of the fossil displays were moved to the new setting. Vertebrate fossils found a home in the 80,000 square foot southeast court. Gradually, the Megaloceros and British Museum casts were joined by many more crowd-pleasing skeletons, including a copy of the Philadelphia Hadrosaurus, an Edmontosaurus, a Triceratops, and a mastodon (discussed below). By the time the USNM was preparing to move to yet another new building across the national mall in 1910, the southeast court had become quite crowded. Unfortunately, the Megatherium and Collossochelys never made it to the new location. These casts were discarded due to the damage they had accumulated while on display. Although the glyptodont cast was still on exhibit as of 1940, it too was eventually destroyed. Happily, the Megaloceros survived, and has been included in each subsequent iteration of the fossil exhibits.

Starting in 1974, the Megaloceros was displayed alongside the extinct bird Diornis in the Ice Age hall. It’s weight was partially supported by cables descending from the ceiling, which proved to be a problem when it came time to disassemble it in July 2014. Rather than attempting to lift the delicate skull and heavy antlers off the armature, the exhibit team strapped the skull to a mechanical lift so that it could be slowly and gently lowered to the floor. In the new National Fossil Hall, the Megaloceros will be sitting on the ground. This pose was selected in order to bring the spectacular antlers to visitors’ eye level.

The Mastodon

The Indiana mastodon in the Hall of Extinct Monsters. Photo courtesy of the Smithsonian Institution Archives.

In 1901, Michigan farmer Levi Wood found a well-preserved, nearly complete Mammut americanum (USNM 2106) in a peat swamp on his land. The USNM purchased the rights to excavate the skeleton from Wood and began work that same year. The specimen turned out to be virtually complete, save for the forelimbs and left hindlimb. Alban Stewart mounted the skeleton, adding a left hindlimb from another mastodon specimen from Missouri, and filling in other missing elements with plaster replicas. The completed mount was first exhibited at the Louisiana Purchase Exposition in St. Louis, Missouri in 1904.

For a time, there were two mastodon mounts on display in the Hall of Extinct Monsters. Photo courtesy of the Smithsonian Institution Archives.

After the Exposition, the Michigan mastodon was added to the fossil displays in the  southeast court of the Arts and Industries Building. It remained there for four years, before joining the rest of the paleontology exhibits and collections in the move to the new USNM building.

In 1915, a second mastodon (USNM V 8204) from Indiana was added to the Hall of Extinct Monsters. The matching set can be seen on the left side of the image above, with the plaster skull of a Deinotherium (USNM V 1917) positioned between them. The larger Indiana mastodon persisted through the 1963 and 1981 renovations, and will return with an energetic trumpeting pose in 2019. NMNH loaned the Michigan mastodon to the Oregon Zoo for many years. It has since been returned, dismantled, and retired to the collections.

The Stegomastodon

Stegomastodon in 2014. Photo by the author.

Stegomastodon in 2014. Photo by the author.

The young male Stegomastodon (USNM 10707) was collected by James Gidley and Kirk Bryan collected this skeleton in the San Pedro Valley of Arizona. This 1921 collecting trip also produced the museum’s Glyptotherium. 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.

Stegomastodon with

Stegomastodon with its original tusks. Photo from Gidley 1925.

The Stegomastodon will not be returning when the National Fossil Hall reopens in 2019. For one thing, 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.

The Eremotherium pair


The unique and impressive Eremotherium pair. Photo by the author.

The immense pair of giant ground sloths (USNM V 20867 and USNM V 20872) are among the most impressive and unique skeletal mounts at NMNH. Many a visitor has ascended the ramp to the Ice Age gallery only to stop and stare at them. Unlike the Megaloceros, mastodon, and many others, these were new additions added during the 1960s modernization. Gazin’s team recovered the fossils in Panama between 1950 and 1951, bringing back over 100 plaster jackets representing at least eight individual sloths of the genus Eremotherium.


John Ott and Gladwyn Sullivan attach the scapula of the standing sloth. Source

Assistant Curator of Cenozoic Mammals Clayton Ray oversaw the assembly of the two Eremotherium mounts in 1969. Both the larger standing sloth and smaller kneeling one are composites of fossils from many individuals (there are also plenty of reconstructed bones, easily spotted by their solid beige coloration). Most of the surplus bones were repatriated to Panama before the mounts went on display. The sloths were originally positioned back-to-back on a central platform, accentuated by an illuminated opening in the ceiling. However, this layout only lasted a few years. In 1974, the Quaternary Hall was completely reorganized into the Hall of Ice Age Mammals and the Age of Man. In the new arrangement, the Eremotherium pair was relocated to a corner at the north end of the gallery. In 2019, only one Eremotherium will be on display.

The Mammoth

Chimera mammoth

This mammoth was assembled from as many as 70 individual specimens. Photo by the author.

Although it was always labeled as a woolly mammoth (Mammuthus primigenius), the Smithsonian’s third proboscidian skeleton (USNM V 23792) is actually a composite of over fifty individual specimens, some of which probably belong to the more southerly Columbian mammoth (Mammuthus columbi). Most of these fossils were acquired in a trade with the American Museum of Natural History in the 1960s, specifically to build a mounted skeleton for the Ice Age hall. Perhaps because they were acquired for display, rather than study, the origin of these fossils was not well-recorded. It is only now that the mammoth has been disassembled that collections staff can begin to to learn more about this iconic chimera. Some of the bones are marked with the year and location of their collection, crucial details for piecing together their provenance.

The mammoth in its new, snow-shoveling pose. Photo courtesy of the Smithsonian Newsdesk.

In the new fossil hall, the mammoth will be leaning forward, pushing its great tusks across the ground as though it were brushing away snow. In the meantime, the original mount was digitally scanned, and the model is freely available from Smithsonian 3D.


Carrano, M. 2018. Pers. comm.

Gazin, C.L. 1956.  Exploration for the remains of giant ground sloths in Panama. Smithsonian report, 341-354.

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

Gilmore, C.W. 1906. Notes on Some Recent Additions to the Exhibition Series of Vertebrate Fossils. Proceedings of the United States National Museum No. 30.

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 No. 90.

Marsh, D.E. 2014. From Extinct Monsters to Deep Time: An ethnography of fossil exhibits production at the Smithsonian’s National Museum of Natural History.


Filed under Extinct Monsters, field work, fossil mounts, history of science, mammals, museums, NMNH