The Other Marsh Dinosaurs


A close-up of Allosaurus. Photo by the author.

Click here to start the NMNH series from the beginning.

Some time ago, I wrote about the O.C. Marsh dinosaurs at the National Museum of Natural History. These are the mounted skeletons made from the enormous collection of fossils Marsh accumulated while working for the United States Geological Survey – if you’d like, you can catch up with Part 1 (on Edmontosaurus and Triceratops) and Part 2 (on Camptosaurus, Ceratosaurus, and Stegosaurus). Looking back, I noticed that I never actually finished, so here are the two Marsh dinosaurs with as-yet untold stories.

The Thescelosaurus

The name Thescelosaurus neglectus means “neglected wonderful lizard”, because Smithsonian paleontologist Charles Gilmore found the original specimen at the bottom of a crate, more than 10 years after it arrived at NMNH. Still buried its its field jacket, this skeleton had been long overlooked by both Marsh and the museum staff. Nevertheless, Gilmore found that it was remarkably complete and that it represented a taxon new to science.

Gilmore's illustration

An illustration of the Thescelosaurus holotype prior to reconstruction. Source

The specimen that would become the Thescelosaurus holotype (USNM 7757) was excavated by John Bell Hatcher and William Utterback in July of 1891, while they were collecting for Marsh in Niobrara County, Wyoming. 20 years later, Gilmore discovered that the skeleton was articulated and intact, save for the head, neck, and parts of the shoulder. He even found small patches of preserved skin on the tail and legs. According to Gilmore, the animal had been buried rapidly after death, since it showed no signs of dismemberment by scavengers.

After describing the fossils, Gilmore had the Thescelosaurus mounted in relief on its left side. Other than the reconstructed skull (modeled after Hypsilophodon), the specimen was displayed almost exactly as it was found. This was important to Gilmore, because as he wrote in his published description, “I am…of the opinion that specimens so exhibited hold the attention of the average museum visitor far longer and arouse a keener interest in the genuineness of the specimen than does a skeleton that has been freed from the rock and mounted in an upright, lifelike posture.” Today at least, I suspect that the opposite is true –  visitors are generally more impressed by dynamic standing mounts than by reliefs that preserve death poses. Still, it’s fascinating to gain a small amount of insight into the motivations of a pioneering mount-maker.

Thescelosaurus at USNM.

Thescelosaurus as displayed after 1981. Photo by Chip Clark.

Although it was first displayed in the Hall of Extinct Monsters, the Thescelosaurus was most prominently exhibited in the 1963 version of the NMNH fossil halls. Here, it joined the Edmontosaurus, Gorgosaurus, and partial Corythosaurus relief mounts along the south wall. In life, these animals were vastly removed from one another in time and space, but displayed together they almost appeared to be parts of a single quarry face. The Thescelosaurus moved to the north wall in 1981, unfortunately placed rather high and out of most visitors’ line of sight. Like the rest of the classic NMNH dinosaur mounts, this specimen is currently undergoing extensive restoration. Should it return in 2019, it will need a new head – in 2014, paleontologist Clint Boyd described the cranial anatomy of T. neglectus for the first time based on two recently discovered skulls.

The Allosaurus

Now that we have the boring ornithopod (oxymoron?) out of the way, let’s move on to the cool specimen! Built in 1981, the Allosaurus fragilis (USNM 4734) is the newest mount assembled from Marsh Collection fossils, although bits and pieces have been on display at NMNH since 1920. There has been considerable interest in this individual recently, in part because Kenneth Carpenter and Gregory Paul proposed in 2010 that it become the neotype for Allosaurus – more on that in a moment. Others are interested in this specimen because of its unique pathologies. In addition to several broken and healed bones, the Allosaurus has a massive puncture wound on its left scapula, which nicely matches the diameter of a Stegosaurus tail spike.

Reconstructed skull

Allosaurus skull  as reconstructed by Norman Boss. Image from Gilmore 1920.

Benjamin Mudge collected this specimen in 1877 near Cañon City, Colorado. Known as the Garden Park quarry, this site also produced the Stegosaurus, Camptosaurus, and Ceratosaurus on display at NMNH. Although the Smithsonian obtained the Allosaurus with the rest of the Marsh Collection around 1900, Gilmore did not look at it (or any of the theropod material) until at least 1911. All told, USNM 4734 consists of a partial skull and jaw, a complete set of presacral and sacral vertebrae, part of the tail, a few ribs, a pelvis, and virtually complete arms and legs. Norman Boss assembled a reconstructed skull, which was displayed through the 1970s. The articulated legs and feet were exhibited in a free-standing case until the late 1950s.

This specimen’s taxonomic history merits some discussion. The holotype Marsh selected when naming Allosaurus (YPM 1930) is notoriously poor, consisting of a single phalanx, two dorsal centra, and a tooth. Dozens of very complete skeletons attributed to Allosaurus are now known, and most specialists basically agree on what an Allosaurus is, but the lack of a usable type with which to define the taxon has been an ongoing problem.

Allosaurus legs

Mounted Allosaurus legs in the Hall of Extinct Monsters. Photo Courtesy of the Smithsonian Archives.

The far more complete USNM 4734 was recovered from the same quarry as the Allosaurus holotype, during the same 1877 field season. Marsh himself actually used this specimen, rather than his designated type, to illustrate subsequent publications on Allosaurus. In 1920, Gilmore flirted with the idea of nominating USNM 4734 as a neotype for Allosaurus, but for reasons that I find difficult to follow, he decided to lump both specimens into the older name Antrodemus valens. Joseph Leidy coined Antrodemus in 1870 based on a single caudal vertebra with no geologic provenance, so this move did little to fix the underlying issue. Nevertheless, Antrodemus remained a popular synonym for Allosaurus in some circles for several decades.

When the NMNH fossil halls were renovated in 1981, the designers presumably noticed that the exhibit badly needed a large theropod mount. Ken Carpenter was tapped to design and construct a complete mounted version of USNM 4734. The Allosaurus measures 17 feet from its grinning jaws to the tip of its tail, and a form-hugging armature makes it look particularly dynamic. This mount has been a favorite among visitors for more than 30 years, although the 2001 addition of a Stan the Tyrannosaurus cast has somewhat overshadowed the smaller theropod.


The complete Allosaurus skeleton was finally exhibited in 1981. Photo by the author.

Technicians from Research Casting International took down the Allosaurus in the summer of 2014 as part of the current round of renovations. You can watch a video of the de-installation here. The skeleton will be remounted in a few years, but Smithsonian researchers want to get a good look at it before that happens. In particular, curator Matt Carrano has been wondering for some time whether a partial jaw Marsh named “Labrosaurus ferox” actually belongs to this specimen. The “Labrosaurus” jaw, which has an unusual pathology caused by a bite or twisting force, came from the same quarry as USNM 4734, and appears to be the same portion of jaw that the more complete skeleton is missing. Time will tell whether Carrano’s hunch is correct. Meanwhile, Carpenter and Paul’s petition to replace the Allosaurus type with this more complete specimen from the same locality is still pending. We should expect to hear more about that soon, as well.


Carpenter, K., Madsen, J.H., and Lewis, L. (1994). Mounting of Fossil Vertebrate Skeletons. Vertebrate Paleontological Techniques. 285-322.

Gilmore, C. M. (1915). Osteology of Thescelosaurus, an ornithopodus dinosaur from the Lance Formation of Wyoming. Proceedings of the U.S. National Museum 49:2127:591–616.

Gilmore, C.M. (1920). Osteology of the Carnivorous Dinosauria in the United States National Museum with Special Reference to the Genera Antrodemus (Allosaurus) and CeratosaurusUnited States National Museum Bulletin 110:1-154.

Lee, J.J. (2014). The Smithsonian Disassembles its Dinosaurs. National Geographic Online.

Paul, G.S. and Carpenter, K. (2010). Allosaurus Marsh, 1877 (Dinosauria, Theropoda): proposed conservation of usage by designation of a neotype for its type species Allosaurus fragilis Marsh, 1877. Bulletin of Zoological Nomenclature 67:1:53-56.


Filed under dinosaurs, exhibits, Extinct Monsters, fossil mounts, museums, NMNH, ornithopods, theropods

Permo-Triassic Synapsids at NMNH

Click here to start the NMNH series from the beginning.

In the middle decades of the 20th century, museum theory and paleontological science were undergoing complementary revolutions. Museum workers shrugged off their “cabinet of curiosity” roots and embraced visitor-centric, education-oriented exhibits. Designers began to envision the routes visitors would travel through an exhibit space, and consider how objects on display could contribute to holistic stories. Meanwhile, paleontologists like Stephen J. Gould and David Raup moved their field away from purely descriptive natural history, exploring instead how the fossil record could inform our understanding of evolution and ecology. The common thread between both transitions was a focus on connections – bringing new meaning and relevance to disparate parts by placing them in a common narrative.

Between 1953 and 1963, the Smithsonian implemented an institution-wide modernization program, transforming virtually every exhibit in the museum complex. The National Museum of Natural History began renovations to its classic fossil halls in 1959, and the new exhibits were emblematic of contemporary trends in both museum design and paleontology. The plan, as devised by exhibit designer Ann Karras, was to do away with the loose arrangement of specimens and turn the east wing into a guided narrative of the biological and geological history of Earth. Responsibility for selecting specimens and writing label copy in each of the four halls fell to a different curator. In Hall 2, which housed dinosaurs and fossil reptiles, that curator was Nicholas Hotton.

Layout of the USNM east wing, circa 1963.

Layout of the NMNH east wing as of 1963.

Hotton joined NMNH in 1959 as an Associate Curator of Paleontology. Entirely onboard with Karras’s vision and the paleobiology movement as a whole, Hotton described the old exhibits as “crowded” and “unorganized.” He thought NMNH had plenty of dinosaurs, but “mammal-like reptiles”* were sorely needed if Hall 2 was to tell the complete story of amniote evolution. Following that, Hotton’s mission over the next several years was to assemble a respectable collection of synapsid specimens for NMNH, and to incorporate them into a well-illustrated exhibit on the origins of mammals. This post highlights just a few of the specimens featured in Hotton’s version of Hall 2.

*In Hotton’s day, early mammalian relatives were usually called “mammal-like reptiles”, hence their inclusion in the fossil reptile exhibit. Today, most specialists prefer a more precise definition of reptiles that excludes synapsid (mammal-line) animals. In this post, I will be using the modern classification wherever possible. 

The Dimetrodon

Prior to 1960, the non-mammalian synapsid collections at NMNH were mostly limited to early Permian pelycosaurs. The most impressive of these was a Dimetrodon gigas collected in 1917 by independent fossil hunter Charles Sternberg. One of the best collectors of his day, Sternberg worked intermittently for E.D. Cope, O.C. Marsh, and various American museums. In the summer of 1917, however, Sternberg was on a personal collecting trip with his son Levi. Their target was the Craddock Ranch bone bed of Baylor County, Texas, which was first explored in 1909 by a University of Chicago team. Sternberg was already quite familiar with this part of western Texas, having made some of the first thorough surveys of the Permian “red beds” in the 1880s, but the site itself was new to him. Nevertheless, Sternberg was extraordinarily successful that summer, collecting hundreds of fossils from a wide range of animals. He offered this bounty to the Smithsonian, and they purchased it from him immediately.

The Craddock Ranch fossils were particularly appealing because of their unique preservation. Buried in soft clay at the bottom of a shallow pond, the fossils had been removed from the ground with relative ease, and were largely free of encrusting matrix. Although few of the bones were articulated, many were identifiable. All told, the Sternberg collection included at least 35 skulls and partial skeletons from amphibians like Cardiocephalus, Diplocaulus, and Seymouria, plus hundreds of individual Dimetrodon bones, and a single articulated Dimetrodon specimen.

Note short tail

An early photograph of the Dimetrodon mount. Image from Gilmore 1919.

Dimetrodon first displaed on north wall

The Dimetrodon was first displayed on the north wall of the Hall of Extinct Monsters. Source

That Dimetrodon (USNM 8635) was the basis for a mount constructed by T.J. Horne. The articulated skeleton included a complete series of presacral vertebrae, the shoulder girdles, most of the forelimbs, and the left femur and tibia. The skull and jaw bones were found disarticulated, but bound together in the same mass of matrix as the skeleton. Horne added the pelvic bones and sacrum from smaller Dimetrodon specimens, and sculpted the rest of the missing material in plaster to complete the mount. Notably, his reconstructed tail was extremely short and stubby. Although the American Museum and Field Museum already had Dimetrodon mounts on display, the NMNH version stood out because of its open jaws, which Charles Gilmore said “gives the animal an appearance of angrily defying one who has suddenly blocked his path.”

Gilmore added the Dimetrodon to the Hall of Extinct Monsters in 1918. Like the other standing mounts constructed under Gilmore’s supervision, the skeleton was placed on a base textured and painted to resemble the rocks in which it was found. At this point in time, the NMNH fossil halls lacked any overarching organizational scheme, and interpretive content was minimal. Nevertheless, Gilmore displayed the Dimetrodon mount with both a small model and a 15-foot oil painting by Garnet Jex, which provided general audiences a better understanding of the animal’s life appearance.


Dimetrodon in the 1963 fossil reptiles exhibit. Image courtesy of the Smithsonian Institution Archives.

Dimetrodon in 2014. Photo by the author.

Dimetrodon after the 1981 renovation. Photo by the author.

During the 1962 renovation, Hotton re-contextualized the classic Dimetrodon mount as a mammal ancestor. Unmissable orange arrows pointed to the specific anatomical traits that signify the animal’s kinship with mammals, including heterodont teeth and a single temporal fenestra. By design, visitors would pass Dimetrodon before visiting the true mammals in the adjacent hall.

The Dimetrodon skeleton itself was altered during the next renovation in 1981, when it was placed on a new, untextured base and given a longer replica tail. Contemporary staff also repainted the plaster sections to more closely resemble the original fossils – a surprising reversal of Gilmore and Horne’s original intention to make the reconstructed bones obvious to viewers.

The Thrinaxodon

Pelycosaurs like Dimetrodon were the first major synapsid radiation, but by the middle Permian they were almost entirely replaced by therapsids. A more derived group which includes modern mammals, therapsids spread across the globe and became increasingly diverse as the Permian progressed. From weasel-sized burrowers to multi-ton herbivores, non-mammalian therapsids were among the first animal groups to conquer a wide range of terrestrial niches. Hotton wanted to tell this story in the modernized fossil exhibit, but there were hardly any non-mammalian therapsids in the NMNH collections. To correct this problem, Hotton took to the field for several months in 1960, and again in 1961. He joined James Kitching in exploring the Beafort Group rocks of South Africa, which were known to produce plentiful Permian and Triassic vertebrate fossils. Hotton returned to the museum with over 200 new specimens, the best of which were used in the renovated exhibit.

Thrinraxodon with Cynognathus skull

Thrinaxodon paired with Cynognathus skull. Photo by the author.

Hotton’s most prized find from South Africa was a gorgeously preserved and nearly complete Thrinaxodon liorhinus (USNM 22812). Hotton called this specimen “Baby Doll”, and while it was not prepared in time for Hall 2’s 1963 opening, it would later earn a spot of honor in the exhibit. Before that happened, though, Baby Doll was actually stolen by an over-enthusiastic volunteer. The FBI located and returned the fossil a year and a half later.

Since the 1970s, the Thrinaxodon has been displayed alongside the skull of Cynognathus crateronotus (USNM 22813), which Hotton collected on the same expedition. Both are members of the cynodont clade, which includes some of the closest relatives of modern mammals.

 The Daptocephalus

Less than a month after hall 2 reopened, Nicholas Hotton returned to South Africa. This time, he was accompanied by his spouse Ruth Hotton and their three young children. For seven months, the Hottons traveled among fossil sites on different ranches, camping most nights. They collected some 300 specimens for the Smithsonian, and Hotton’s biostratigraphic mapping of the Beaufort Group brought a measure of clarity to this region’s historically convoluted geology.

Ruth Hotton made one of the trip’s most impressive finds while prospecting in a dry riverbed with her daughter, Carol (who is now a paleobotanist at NMNH). Turning a corner, she stumbled upon a dicynodont skeleton, completely exposed and lying in the middle of the channel. One can only imagine the surprise and delight of finding an articulated fossil skeleton completely uncovered. If the Hottons had been there one season earlier or one season later, the river would have undoubtedly destroyed the fossils.


“Daptocephalus” as exhibited after 1981. Source

Photo by Christian Kammerer

Close up of the erroneously reconstructed skull. Photo by Christian Kammerer.

Back at the museum, Nicholas Hotton prepared the specimen (USNM 299746) and determined it to be Daplocephalus leoniceps, one of the plethora of dicynodonts known from the Beaufort Group. Based on this classification, he reconstructed the badly damaged skull to resemble more complete Daplocephalus specimens, and added casts of Daplocephalus limbs. As it turns out, however, USNM 299749 is not a Daplocephalus – it is a somewhat distantly related dicynodont currently called Odontocyclops (also subject to change). To varying degrees, fossil mounts are hypotheses made of bone and plaster. They are based on the best information available at the time, but sometimes they need to be corrected. The NMNH “Daplocephalus” has been mislabeled and erroneously reconstructed for many years, but the current renovation of the NMNH fossil halls now presents an opportunity to deconstruct the specimen and study it up close.

Thanks to Christian Kammerer for kindly sharing images and insight on “Daptocephalus”!


Gilmore, C.W. (1919). A Mounted Skeleton of Dimetrodon gigas in the United States National Museum, with Notes on the Skeletal Anatomy. Proceedings of the United States National Museum 56:2300:525-539.

Kammerer, C. (2015). Personal communication.

Lay, M. (2013). Major Activities of the Division of Vertebrate Paleontology During the 1960s.

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.

Sepkoski, D. (2012). Rereading the Fossil record: The Growth of Paleobiology as an Evolutionary Discipline. Chicago, IL: The University of Chicago Press.


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

Fossil sandboxes are terrible

Are these kids learning yet?

Are these kids learning yet? Source

Today, I need to take a moment to rail against one of the most reliably entertaining and beloved of museum attractions – fossil sandboxes. These activities are nearly ubiquitous at paleontology-related parks and museums, and some of them can be quite large and elaborate. There are a few variations, but they generally involve children using simple hand tools to dig through sand or loose gravel to uncover planted fossils (usually replicas, but I’ve seen a few places sacrifice real Pleistocene bones for this activity). Kids and families absolutely adore fossil sandboxes, and they generate all kinds of goodwill for the museums that feature them. In fact, many visitors have come to expect sandbox digs at paleontology exhibits, and become annoyed when one isn’t available.

I understand the appeal of sandboxes. For kids, they’re an opportunity to play pretend, engage in a physical activity after a day of looking at stuff, and generally have fun making a mess. Museum educators, myself included, are all about Gardner’s theory of multiple intelligences – the idea that different people learn best in different ways. While some easily absorb and retain information by reading or listening quietly, others prefer to solve a problem, talk through a topic with others, or engage in some sort of hands-on activity. That last one is called bodily-kinesthetic intelligence, and it is common among athletes and actors, among others. A fossil sandbox allegedly provides an activity for bodily-kinesthetic learners to develop and hone a physical skill related to the topic at hand. Kids get a chance to see and feel what it’s like to be a real paleontologist working in the field.

Except not really. A sandbox focuses kids’ attention, but that’s not the same thing as learning. What they’re doing has virtually nothing to do with actual paleontology. Digging is a comparatively minor part of field work – far more time is spent prospecting for fossils. When a team does start excavating, it’s conducted in a precise and organized manner, so that no taphonomic data is lost. By comparison, the sandbox arrangement conjures ideas of frantic treasure hunting, rather than piecing together and interpreting clues about past life. Furthermore, digging through loose sand is exceedingly rare in the field. If it were so easy to get at fossils, they would either have been found already or would have eroded away to nothing. A simulation is supposed to model a real event, or constrain that event to a limited set of variables. Sandbox digs do neither. Parents and caretakers might appreciate a place where kids can entertain themselves for a while, and educators can pat themselves on the back for providing a physically-involved experience. But there’s no use pretending that anybody is learning in what amounts to a themed playpen.

One alternative to the sandbox concept is provided by Thistle. He describes an activity in which he sets up a series of square meter “dig sites” within a room. Different specimens or artifacts are placed in each square. Participating students are then told that each square represents what was found in a layer of excavation, and are prompted to draw conclusions based on the different objects recovered from different strata. Students consider the spatial relationships among found objects, and discuss the roles of taphonomy and deep time. Unlike a sandbox dig, the results of this activity are comparable to those of a real excavation, and students are asking the same sorts of questions paleontologists would. Granted, Thistle’s activity requires much more guidance than a sandbox, but it’s a good example of something that participants might actually learn from.

The point is, we owe our audiences more than a mindless diversion with no bearing on actual science. And for that matter, we owe the scientists whose work we’re communicating more than a tacky, inaccurate simulation. If our goals are to inspire enthusiasm for science and to encourage young visitors to think scientifically, surely we can do better than a sandbox dig.


Thistle, P.C. 2012. Archaeology Excavation Simulation: Correcting the Emphasis. Journal of Museum Education 37:2:65-76.

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Filed under education, exhibits, field work, museums, opinion, science communication

History of the AMNH Fossil Halls – Part 2

Start with History of the AMNH Fossil Halls – Part 1.

During his leadership of the American Museum of Natural History’s Department of Vertebrate Paleontology and later, the museum at large, Henry Osborn oversaw an unprecedented expansion of the institution’s paleontology exhibits. As fossils poured in from the Department’s international collecting expeditions, these displays expanded into five separate galleries on the museum’s fourth floor. During the first two decades of the 20th century, AMNH staff was installing newly prepared and mounted specimens every single year. In it’s heyday, AMNH was the undisputed center of American vertebrate paleontology. The increasingly marginal role of descriptive natural history in the greater field of biology at this time made the scale of Osborn’s program all the more impressive.

Nevertheless, this golden age of fossil exhibits would not last forever. Osborn supported the expensive expeditions and monumental displays through his personal connections with wealthy benefactors. The combination of the Great Depression and Osborn’s death in 1933 all but eliminated this source of income, and the museum had to scale back its activities considerably. In 1942, the Department of Vertebrate Paleontology was dissolved. Paleontology work continued under the Department of Geology, but with only a fraction of its former staff and budget.

Phase IV: 1940 – 1955


In the post-Osborn era, responsibility for the fourth floor exhibits deservedly transferred to Barnum Brown. Indeed, Brown’s adventures as a swashbuckling fossil hunter not only brought him personal fame, but made the museum’s world-class paleontology exhibits what they were. Of the 36 dinosaurs on display by 1939, no less than 27 had been discovered by Brown. Most of these iconic finds were made in his 20s and 30s, but Brown nevertheless remained at AMNH for most of his life. Even after officially retiring in 1943, Brown still frequented the museum, often giving spontaneous personal tours of the exhibits.

brown's jurassic hall

Brown’s Jurassic Hall, around 1940. Photo from Dingus 1996.

In 1932, the architectural firm Trowbridge and Livingston completed the 13th building in the AMNH complex. This meant that for the first time, the paleontology exhibits formed a complete circuit, an arrangement that persists to this day. Brown opted to spread the dinosaurs into two halls, making the new space the Jurassic Hall and converting the Osborn-era Great Hall of Dinosaurs into the Cretaceous Hall. Several existing fossil mounts had to be moved as a result, including the massive “Brontosaurus.”  Eyeballing the widths of the doorways and corridors separating the present day Hall of Saurischian Dinosaurs (formerly the Jurassic Hall) and Hall of Ornithiscian Dinosaurs (formerly the Cretaceous Hall and Great Hall of Dinosaurs), it’s difficult to imagine how museum staff could have moved the 66-foot sauropod in one piece. This photograph suggests that the skeleton was divided into several sections, which then had to be brought down the freight elevator on one side of museum and carted around to an elevator on the other side. This would be the third and final position for the “Brontosaurus” – even when the mount was updated  in 1995, preparators left the torso and legs in place.

brown's cretaceous hall

Brown’s Cretaceous Hall, around 1939. Photo courtesy of the AMNH Research Library.

The 1930s and 40s saw a number of new dinosaur mounts added to the displays, nearly all of which were discovered by Brown. The new Jurassic Hall gained a Stegosaurus and Tenontosaurus (oddly not a Jurassic dinosaur), and the Cretaceous Hall gained Brown’s astonishingly intact CentrosaurusCorythosaurus, and Styracosaurus from Alberta.

Phase V: 1956 – 1990


Edwin Colbert joined AMNH in 1930 as Osborn’s assistant (he called this “a time of experiences and incidents,” whatever that means). Eventually rising to Curator of Vertebrate Paleontology, Colbert was one of only a handful of mid-century researchers studying dinosaurs. He is also notable for his public outreach – in collaboration with his spouse, Margaret Colbert, he wrote more than 20 popular books about paleontology.

In 1953, Colbert worked with exhibit specialist Katharine Beneker to redesign the Jurassic and Cretaceous Halls. The Jurassic Hall received the more dramatic aesthetic makeover – windows were covered up to create a “black box” effect, while the dinosaur mounts were illuminated dramatically from above and below. Surprisingly, the most significant addition to this space wasn’t a standing mount, but a trace fossil. Exhibit developers incorporated several slabs of sauropod tracks (collected at the Paluxy River in Texas by Roland T. Bird) into the central pedestal, as though left behind by the “Brontosaurus.” Cemented together, the slabs weighed 22 tons – apparently nobody expected that they would ever need to be moved. The fossil fish alcove, formerly part of the 1905 Hall of Fossil Reptiles, also found a home in this space.

In stark contrast to the Charles Knight oil and watercolor murals commissioned by Osborn, Colbert elected to decorate the Jurassic Hall with a series of understated chalk drawings. Joseph Guerry created the artwork, which was then projected onto the walls and traced in chalk. The initial plan was to paint over the chalk outlines, but Colbert enjoyed the blackboard-like look and left them as they were. The exhibit team didn’t even add fixative, since it would have turned the lines an unpleasant yellow.

Jurassic hall colbert. Photo from Dingus 1996.

The Jurassic – or Brontosaur – Hall opened in 1953. Photo from Dingus 1996.

Architectural modifications to the Cretaceous Hall were minimal, although the standing dinosaur mounts were all clustered on a single platform. Interestingly, both the National Museum of Natural History and the Peabody Museum of Natural History would arrange their dinosaurs in precisely the same way within the decade. While it’s possible that these museums were copying AMNH, this similarity is probably a reflection of the transition to more holistic natural history displays that was occurring in museums nationwide. Rather than displaying specimens individually, exhibit designers in the 1950s and 60s began to arrange them in meaningful ways – for example, grouping animals with a shared habitat. The Cretaceous Hall also gained some new specimens, including an array of Protoceratops skulls recovered during the Central Asiatic Expeditions. Signs and labels were updated with more approachable language, once again reflecting contemporary museum theory.

colbert cretaceous hall

The Cretaceous – or Tyrannosaur – Hall opened in 1954. Photo courtesy of the AMNH Research Library.

Meanwhile, some of the oldest AMNH fossil exhibits were retired and replaced during this period. In 1961, the classic geology hall – the oldest exhibit on the fourth floor – became the research library and was closed to regular museum visitors. Its spiritual successor was the new Earth History exhibit, which replaced Osborn’s Hall of the Age of Man. Around the same time, George Gaylord Simpson curated what was colloquially known as the “Sloth Hall.” Occupying the space that was once the Hall of Fossil Reptiles, this exhibit featured ground sloths and glyptodonts, plus a sizable display demonstrating how fossils are collected and prepared. Only the Hall of Fossil Mammals remained ostensibly untouched during this wave of modernization.

Superman visits AMNH

Superman visits Apatosaurus in the 1985 documentary, “The Dinosaurs.” Source

The 1950s and 60s iterations of the AMNH fossil halls endured for 30 years, making them the longest-lasting versions to date. Displays like the “Brontosaurus” and Tyrannosaurus became immutable symbols for the institution, visited again and again by generations of museum-goers. However, time gradually took its toll. A large section of the Hall of Fossil Mammals was boarded up, since museum staff had removed so many specimens for study or conservation. Railings were eventually added to the Jurassic Hall, because it was too tempting for visitors to join the dinosaurs on the platform, Ke$ha-style. Most importantly, the exhibit content became increasingly out-of-date with each passing year. This obsolescence permeated nearly every aspect of the exhibits, from the discussion of the dinosaurs’ extinction to the drab, earth-tone aesthetics. However, the most visibly antiquated elements were the fossil mounts themselves. A new wave of dinosaur research demonstrated that these animals had been active and socially sophisticated, a far cry from the the coldblooded tail-draggers that populated the galleries. AMNH had once been the center of American paleontology, but by the late 1980s its dated displays were lagging far behind newer museums.

Phase VI: 1995 – Present


Between 1987 and 1995, Lowell Dingus coordinated a comprehensive, $44 million renovation of the AMNH fossil exhibits (previously discussed here and here). The original plan was to renovate only the Hall of Fossil Mammals, since it had remained largely unaltered since 1895. Within a year, however, the project had expanded to encompass all six halls on the fourth floor, telling the entire story of vertebrate evolution. Two primary goals originated very early in the planning process. First, the “walk through time” layout would be replaced with one rooted in phylogenetic classification. The cladistic methodology for tracing organisms’ evolutionary history became the central theme that unified the new exhibits. This required a fairly substantial reorganization of existing specimens. The mammals could remain in the same two halls, but the denizens of the Jurassic and Cretaceous halls had to be rearranged to feature Saurischian and Ornithiscian dinosaurs, respectively. Meanwhile, the research library moved to a new location to make way for the Hall of Vertebrate Origins.

Advanced Mammals

The Hall of Advanced Mammals was the first renovated exhibit opened to the public. Photo by the author.

The second major goal was to restore the original architecture in each hall, ensuring that both the historic specimens and the spaces they occupied would come “as close to their original grandeur as possible” (Dingus 2006). In many cases original architecture elements – such as the moulded ceilings – were still intact behind panels that had been installed over them. These features were painstakingly restored, or when necessary, recreated. Classic decorative elements, from the colonnades to the elegant chandeliers, were reintroduced.

Apatosaurus remount

The updated Apatosaurus in the Hall of Saurischian Dinosaurs. Photo by the author.

The vast majority of the fossil mounts in the renovated exhibits had already been on display for years. Among the classic mounts, only the two most iconic displays were completely overhauled. The restoration of Apatosaurus (formerly “Brontosaurus”) took more than a year. A conservation team led by Jeanne Kelly worked from a temporary wooden scaffold, filling cracks in the aging fossils with epoxy and securing loose joints on the armature. The mount’s torso and legs remained in place throughout the process, but the neck and tail were dismantled and remounted by Phil Fraley’s exhibit company. In addition to a new head, the revised Apatosaurus gained several caudal and cervical vertebrae, extending its total length to 88 feet. Remounting the Tyrannosaurus rex was even more difficult, because the fossils were so fragile. Once again, Phil Fraley was responsible for disassembling and reposing the skeleton. The T. rex now sports a more accurate horizontal posture, and its weight is supported by steel cables extending from the ceiling.

The new fossil mounts are easily recognized by their dynamic poses. In the Hall of Vertebrate Origins, the amphibian “Buettneria” (now Koskinodon) assumes a diving pose, while a Prestosuchus charges with its tail aloft. Among the dinosaurs, a new Deinonychus mount (assembled in part from previously-unidentified historic material) is posed in mid-leap. Finally, the dog-like Amphicyon chases the tiny antelope Ramoceros in the Hall of Advanced Mammals.

hall of ver

In the Hall of Vertebrate Origins, a new Koskinodon mount represents the vertebrates’ critical transition to terrestrial life. Photo by the author.

The AMNH fossil halls represent one of the most exhaustively complete fossil collections in the world, but these exhibits ultimately tell two stories. On one hand, we have the story represented by the fossils themselves. The exhibit is an extended genealogy, tracing our origins across 500 million years of deep time. On the other hand, we have the museum’s history, which highlights both the praiseworthy and the ugly sides of 20th century science. It reminds us where our society has been and where it needs to go. Both stories are relevant to each and every person passing through these halls, and laudably, the latest renovation highlights both.


Colbert, E.H. (1958). Chalk Murals. Curator 4:10-16.

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

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

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Filed under AMNH, dinosaurs, exhibits, fossil mounts, history of science, mammals, museums, reptiles

History of the AMNH Fossil Halls – Part 1

Much of what I write for this site starts with an attempt to find one reference or another, only to discover that it does not exist online. This time, I was curious how many times the American Museum of Natural History paleontology halls had been renovated, but I quickly found that there was no simple answer.  Unlike the fossil exhibits at the National Museum of Natural History, which have occupied the same large hall since the building opened, the AMNH counterparts have been moving and growing for more than 120 years. The museum expanded organically, eventually encompassing 27 interconnected buildings. And as its footprint grew, the paleontology exhibits grew with it.

The following is my attempt to make sense of the fourth floor exhibit halls’ convoluted history. I’ve divided it into six phases, although this should only be considered a rudimentary outline. Many specimens were added and removed during each phase, particularly during the period of frantic expansion in the early 20th century. At the very least, however, this should be enough to contextualize most of the historic photos made available by the AMNH Research Library. As with my NMNH posts, please note that I will not be discussing field expeditions or scientific discoveries by museum staff, as these topics are well-explored elsewhere. My focus here is solely on the public-facing exhibits, and the people who created them.

Phase I: 1874 – 1904


AMNH was founded in 1869, although the first buildings in Manhattan Square did not begin construction until 1874. The original structure was designed by architect Calvert Vaux. Since electric lights were not yet available, Vaux created exhibit spaces that maximized the impact of natural lighting. Large windows were divided into slits that paralleled rows of glass display cabinets. The sun would shine through the windows and directly into the cabinets, illuminating the specimens within. When the museum first opened, the single exhibit hall on the fourth floor was dedicated to geology specimens. While this space mostly housed rocks, minerals, and small fossils, a handful of mounted skeletons stood among the cabinets. Early acquisitions included a moa and the Pleistocene deer Megaloceros, shown below.

geology hall with moa

Geology Hall, before 1887. Photo from Dingus 1996.

Things changed radically shortly after Henry Osborn was hired in 1891. As a paleontologist, Osborn emerged from Princeton riding the crest of a wave of goodwill his discipline had enjoyed for most of the 19th century. Paleontology was the darling of American science, and one man in particular, O.C. Marsh of Yale, received generous federal funding to find and describe new fossils from the western interior. In the 1880s, however, an economy-minded Congress pulled that funding. Meanwhile, the rise of experimental biology led to the marginalization of descriptive natural history, including paleontology. The next generation of paleontologists needed a new home for their work, and they found it in museums. AMNH was one of several new museums backed by wealthy benefactors with an interest in public education. These benefactors gravitated toward paleontology because, as Ronald Rainger put it, fossils are “rare, valuable, and visible.” The skeletons of extinct monsters were huge and sensational, and naturally complimented the grandiose neoclassical halls of the nascent museums. But while the paleontology programs at institutions like the Carnegie Museum and the Field Museum were quite respectable, they all were overshadowed by Osborn’s Department of Vertebrate Paleontology at AMNH.  Osborn’s goal was to make AMNH the center of American vertebrate paleontology in the post-Marsh world, and by most any measure he succeeded.

Hall of Fossil Mammals, around 1906.

Hall of Fossil Mammals, around 1906. Photo from Dingus 1996.

The next Phase I exhibit was the Hall of Fossil Mammals, which opened to the public in 1895. Osborn’s research was focused on Cenozoic mammals, especially brontotheres, and he tasked his department with assembling a suitably impressive collection. Some of the fossils on display were acquired in an 1897 purchase of Edward Cope’s personal collection. Many others were collected by AMNH staff in the Big Horn Basin of Wyoming. Among these in-house finds was the famous (and famously misleading) series of fossil horses, most of which were found and prepared by William Matthew. The largest and most captivating mounted skeleton on view was the Warren mastodon. Discovered in 1845 in a bog near Newburgh, New York, this specimen was the first complete mastodon ever found. It was initially described and displayed by Boston-based anatomist John Warren, but Osborn convinced J.P. Morgan to buy it for AMNH in 1906.

Aside from a few shuffled mounts (including the aforementioned mastodon, which seems to have been in nearly every room on the fourth floor), the Hall of Fossil Mammals remained mostly intact for the duration of the 20th century. Shortly after it was completed, the Department of Vertebrate Paleontology shifted its focus to dinosaurs. The mammals were only the star attractions for a few short years, but this display would nevertheless endure in its original form for generations.

Age of Man

Hall of the Age of Man, around 1915. Photo from Dingus 1996.

At this point, it is crucial to mention that Osborn was an objectively lousy scientist, and that much of his work was motivated by a bigoted personal agenda.  He subscribed to an inaccurate orthogenetic (or as he called it, “aristogenetic”) interpretation of evolution, professing that all life forms had their place in a natural hierarchy. According to Osborn, people of Anglo-Saxon and Scandinavian ancestry were the pinnacle of existence, and he endeavored to turn his flagrantly racist beliefs into public knowledge by way of his exhibits. Nowhere is this clearer than the Hall of the Age of Man, which opened around 1900. This hall included a range of extinct animals that coexisted with early humans, but the central cases were dedicated to Osborn’s unorthodox narrative of human evolution. Hominid fossils were co-opted to illustrate Osborn’s unfounded view that modern human races were evolutionarily distinct, and to communicate his support for eugenics and racial purity. Osborn’s agenda was supported by many of the aristocratic elite that funded the museum, but apparently few of the AMNH research staff endorsed it. Margaret Mead in particular was highly critical of Osborn’s views, and especially his influence over public-facing interpretation.

Phase II: 1905 – 1920


Edit: The map above should read “Invertebrate Fossils and Minerals.” 

For all of Osborn’s bigotry and bad science, it’s difficult to imagine the modern museum field without his influence. He was very good at marketing himself and his paleontology program, and he knew how to put on a show that would attract visitors in droves. Osborn heightened the standards for public exhibitions, investing in lifelike habitat dioramas of taxidermy animals and spectacular fossil mounts in order to make science exciting for a wide audience. Osborn’s devotion to storytelling and drama in the exhibits he curated brought millions of visitors to AMNH and defined public expectations for what museums should offer.

In 1906, Osborn became the fourth president of AMNH, and he oversaw its most rapid period of expansion. As president, he tripled municipal funding for the museum from New York City, and gained plenty more through his connections with wealthy potential donors. Much of this income was funneled into the Department of Vertebrate Paleontology’s famous dinosaur collecting expeditions, in which fossil hunters like Barnum Brown and Walter Granger earned fame and notoriety. However, the pioneering work on fossil preparation and mounting at AMNH was also significant. While many peer institutions were assembling and exhibiting new dinosaur mounts during this period, none matched the output or ambition of AMNH. With the sheer quantity of fossils coming in and institutional pressure to mount them for display as quickly as possible, chief preparator Adam Hermann had no choice but to modernize and professionalize his craft. Hermann developed a sophisticated prep lab with overhead tracks for hoisting heavy fossils, as well as electric and pnuematic hook-ups for power tools. Techniques like sand-blasting, acid preparation, and on-site metalworking developed by Hermann are still standard practice today.

trachodon crowded reptile hall

“Trachodon” pair in the Hall of Fossil Reptiles. Photo from Dingus 1996.

Dinosaurs take up a lot of space, and to accommodate them, a new gallery was opened on the far end of the Hall of Fossil Mammals. This Hall of Fossil Reptiles debuted in 1905 with “Brontosaurus” – the first mounted sauropod ever built – as its centerpiece. Actually a composite of four individuals and many sculpted elements (including the way-off-the-mark head), the “Brontosaurus” took Hermann’s team the better part of six years to construct. After that, the Hall of Fossil Reptiles filled with new dinosaur mounts very quickly, cementing the repuation of AMNH as the place to see dinosaurs. In 1906, Hermann added the “Trachodon” pair. The standing individual came from the Cope collection, but the crouching specimen was excavated that very year by Barnum Brown. The Allosaurus was also a Cope specimen, but apparently the 19th century paleontologist had never unpacked or inspected it. Several years passed before Hermann’s team discovered that the skeleton was remarkably complete, although it was missing a skull. The Allosaurus fossils were mounted in 1908, posed as though feeding on a set of Apatosaurus vertebrae.

crowded reptile hall

Tyrannosaurus stands with Allosaurus and “Brontosaurus” in the increasingly crowded Hall of Fossil Reptiles. Photo from Dingus 1996.

Arguably the most important mount added during the early 20th century mounting spree was the Tyrannosaurus rex. This specimen is no less than an icon, and has been a destination attraction in New York for longer than the Empire State Building. When the Tyrannosaurus was unveiled in 1915, it was a sensation, akin to mythical dragon made real. For a generation, AMNH was the only place in the world where visitors could stand in the presence of a T. rex, and to this day the image of the classic mount is quintessential to both paleontology and museums in general. For example, you may recognize it from the cover of a certain Michael Crichton novel.

Phase III: 1921 – 1939


In 1922, the 9th building in the AMNH complex was completed, and the paleontology exhibits expanded into what Osborn called the “Great Hall of Dinosaurs.” The largest dinosaur mounts – including Tyrannosaurus, “Brontosaurus”, “Trachodon”, and Allosaurus – were moved from the comparatively cramped Hall of Fossil Reptiles into this new space. The extra breathing room allowed for the mounts to be clustered into Jurassic and Cretaceous areas on opposite sides of the room. There were also a few new skeletons, including Leptoceratops, Thescelosaurus, and most significantly, Triceratops.

brontosaurus in great dinosaur hall

“Brontosaurus” in the Great Dinosaur Hall, around 1927. Photo courtesy of the AMNH Research Library.

Meanwhile, AMNH fossil collecting efforts had moved from the American West to Mongolia. The primary goal of Roy Chapman Andrews’ Central Asiatic Expeditions was to find evidence for Osborn’s pseudoscientific ideas about human ancestry, but no such remains were found. Instead, the expedition returned a wealth of new dinosaur fossils, including the first dinosaur nests ever found. Dispatches from the field also drummed up considerable publicity for the New York museum.

great dinosaur hall

Tyrannosaurus and Triceratops in the Great Dinosaur Hall, around 1927. Photo courtesy of the AMNH Research Library.

Osborn’s iron-fisted reign over American paleontology lasted until his death in 1933. Unfortunately for the Department of Vertebrate Paleontology, Osborn’s activities depended heavily on personal relationships with private donors. With Osborn out of the picture (and the Great Depression at its bottom), those donations dried up. Meanwhile, Osborn’s good standing in the scientific community had begun to wane, and his unorthodox anthropological ideas became something of a joke. The results of internal investigations into Osborn’s less-than-legitimate use of funds and favors during his time as president did not help matters. In 1942 the Department of Vertebrate Paleontology was dissolved. Paleontology work was folded into the Department of Geology with a much smaller budget and fewer staff. The Osborn-era fossil displays at AMNH remained largely unaltered in the years that followed, but only because of the lack of staff time, money, and interest.

Next week, we’ll wrap up this timeline, passing through the era of Edwin Colbert and into the present day. Stay tuned!


Brinkman, P.D. (2009). Dinosaurs, Museums, and the Modernization of American Fossil Preparation at the Turn of the 20th Century. Fossil Preparation: Proceedings of the First Annual Fossil Preparation and Collections Symposium 21-34.

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

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

Haraway, D. (1984). Teddy Bear Patriarchy: Taxidermy in the Garden of Eden, New York City, 1908-1936. Social Text 11:20-64.

Hermann, A. (1909). Modern Laboratory Methods in Vertebrate Paleontology. Bulletin of the American Museum of Natural History 56:283-331.

Osborn, H.F. (1921). The Hall of the Age of Man in the American Museum. Nature 107:236-240.

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

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Filed under AMNH, anthropology, dinosaurs, exhibits, fossil mounts, mammals, museums, reptiles

Framing Fossil Exhibits: Phylogeny – An Addendum

After I posted my slightly critical evaluation of the AMNH fossil halls last month, a reader suggested I take a look at Next of Kin by Lowell Dingus. Dr. Dingus was the project director for the 1995 renovation, and his book chronicles the decade-long process of overhauling these genre-defining exhibits. It also includes plenty of gorgeous photos of the AMNH fossil exhibits past and present. Although out of print, Next of Kin can be found online for next to nothing. If you find anything on this blog interesting, I would call this book required reading. I cannot recommend it enough.

Edwin Colbert designed this version of the Jurassic exhibit in 1956. This space is now the Hall of Saurichian Dinosaurs. Photo from Dingus 1996.

Next of Kin is full of fascinating information about the renovation, and the history of the halls in general. For instance, it was news to me that the original plan in 1987 was to modernize only the two fossil mammal halls. When William Moynihan took over as Director of AMNH the following year, however, he asked in a planning meeting why the dinosaur exhibits weren’t being renovated, and soon the project expanded to include all six halls on the 4th floor. Apparently the approaches to interpretation, aesthetics, and layout that characterize the exhibits today were already fully formed. The concept of a main pathway with branching alcoves representing individual clades was in place, so the exhibit team only needed to set the starting point back a ways to include the dinosaurs and the rest of the vertebrate family tree. Restoring the historic interior architecture, obscured since the 1950s, was also an early priority. Dingus relates how he wanted to eliminate the “black box” look of the midcentury exhibits and let natural light back into the halls. In my opinion, the well-lit, airy aesthetic is one of the standout features of the AMNH fossil halls, and one other museums might do well to emulate.

Dingus also points out a number of clever design choices that I missed during my last visit to the museum. For instance, the primate section was deliberately placed in the center of the mammal hall, to avoid the implications of directed evolution and human superiority that once marked the AMNH exhibits. Another cool feature is the use of minimalist metal armatures to suggest the size and shape of animals for which only limited material is available. This is an artful way to convey the dimensions of these species without resorting to fabricating most of the skeleton. Again, this is something I’d love to see more of at other museums.

Photo by the author.

Minimalist armatures suggest the size and shape of incomplete specimens. Photo by the author.

Still, I was most interested in reading Dingus’s rationale for the design and layout of the AMNH fossil halls. In my previous post, I argued that the phylogenetic arrangement was a worthwhile experiment, but in practice it may not be the most practical way to make the history of life meaningful to the museum’s primary audience. More than any other organizational scheme, phylogeny is the way biologists think about the natural world, and I applaud the effort to encourage visitors to look at fossils the way scientists do. However, even the most basic elements of evolutionary classification are specialized knowledge, and require a daunting amount of up-front explanation (especially when targeting multiple age groups). I don’t think this integrates well with the multi-entrance, non-linear exhibit space at AMNH.

During the initial planning stages of the AMNH renovation, Dingus and other staff toured several large-scale paleontology exhibits in North America and Europe. Dingus clearly did not like what he saw, lamenting that “some institutions rely heavily on easy-to-understand, anecdotal labels and robotic recreations of dinosaurs that appeal to the lowest common denominator of visitor intellect.” He rejected the “prominent contemporary school of exhibit design that advocates only giving the visitor what he or she asks for,” feeling strongly that his institution could do better. Referring to the renovation as a “scientific crusade,” Dingus was inspired to challenge his audience in a way that peer institutions did not. Dingus and his colleagues wanted to show visitors the real science behind paleontological reconstructions. The phylogeny-based arrangement was central to that goal, emphasizing rigorous anatomical analysis and empiricism in a field historically characterized by idle speculation.

Age of Man

The orientation hall is in the oldest of the 4th floor exhibit spaces. Until the 1960s, this space was occupied by the Hall of the Age of Man. Photo from Dingus 1996.

I agree wholeheartedly with all of this. There was a period in the 80s and 90s (I think the worst is behind us) when the trend toward visitor-focused, educational exhibits got mixed up with a push to make museums more competitive with other leisure activities. Customer enjoyment was valued above all else, even if it meant sacrificing the informative content and access to real specimens that made museums worthwhile institutions in the first place. The resulting displays were filled with paltry nonsense like simulators, pointless computer terminals, and the aforementioned robot dinosaurs*. These exhibits imitated amusement parks, but with only a fraction of the budget they quickly fell into disrepair and technological obsolescence. Despite being museums’ most important and unique resources, curators and research staff found themselves increasingly divorced from their institutions’ public faces.

*Fine, I admit robot dinosaurs are cool. But I’d prefer that they weren’t in museums.

Under these circumstances, a backlash is quite understandable. Nevertheless, it is a common mistake (which I am by no means accusing Dingus of making!) that a visitor-centered exhibit is the same as a frivolous one. When educators push for audience-focused exhibits, they have the same goal as curators: to communicate as much content as possible. Audience-focused exhibits aren’t about dumbing down or eliminating content. They’re about presenting content in a way that effectively reaches the museum’s diverse audience. The AMNH fossil halls would work well for an informed adult visitor with ample time to inspect every specimen and read every label. But this is not the typical audience for natural history museums, and unless AMNH is a major outlier, it’s not the core audience for these exhibits. Most visitors come in mixed-aged groups. The trip to the museum is a social experience, and interactions occur among visitors as much as they occur between visitors and the exhibits. The best museums anticipate and meet the needs of these visitors in order to provide a quality learning experience.


An updated version of the classic (and classically misleading) horse evolution exhibit. Photo by the author.

It’s admittedly fun to share horror stories about dumb comments overheard in museums. Who in this field hasn’t rolled their eyes at the parent who makes up an answer to their child’s question, when the correct information is on the sign right in front of them? And yet, some of the blame for this failed educational encounter should fall on the museum. Why was that parent unable to spot the relevant information with a quick glace? Can we design signage so that the most important information is legible on the move, or from across the room? Can we correct commonly misunderstood concepts in intuitive ways?

As Dingus argues, it’s important to aim high in the amount of information we want to convey. There’s nothing worse than a condescending teacher. But a carefully-honed message in common language will always be more successful than a textbook on the wall. Happily, this is the way the wind is blowing these days. In a strong reversal of the situation a decade ago, curators now work closely with educators on the front lines to produce exhibits that are both accessible and intellectually challenging. It’s been 20 years since AMNH opened the latest version of its fossil exhibits…perhaps a new and even better iteration is already on its way!


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


Filed under AMNH, education, exhibits, fossil mounts, mammals, museums, opinion, reviews, science communication, systematics

The Carnegie Quarry Diaspora

About 150 million years ago, a severe drought ravaged the western interior of North America. In eastern Utah, malnourished dinosaurs gathered near a dwindling river. Unwilling or unable to leave the water source, they eventually died of thirst or disease. When rain finally returned to the region, three or four successive flash floods washed dozens of animal carcasses into a relatively small depositional area to the southeast. Today, this site is known as the Carnegie Quarry at Dinosaur National Monument, and it is one of the most incredible fossil sites in the world.

Dinosaur National Monument interns collect data on the quarry wall.

Dinosaur National Monument interns collect data on the quarry wall. Source

Today, a structure encompassing a 180-foot section of the deposit (less than half its total length) allows visitors to view nearly 1400 dinosaur bones in situ. However, the fossils on display at Dinosaur National Monument represent only a portion of the material found at the Carnegie Quarry. Between the site’s discovery in 1908 and the establishment of the quarry wall exhibit, more than 20 reasonably complete dinosaur skeletons and dozens more incomplete specimens were excavated and distributed to museums in the US and Canada. No less than eleven mounted skeletons have been created from this material, and they are all still on display today. Although they are thousands of miles from their place of discovery and exhibited in four different cities, these mounts all represent individuals that lived and died in the same environment. They may have even encountered each other in life!

The Discovery

Earl Douglass was already an established fossil hunter when the Carnegie Museum of Natural History hired him in 1902. Late in the 1909 field season, Douglass was prospecting near the confluence of the Green and Yampa Rivers when he spotted a series of sauropod vertebrae eroding out of the rocks. Once Douglass and his crew began excavating the fossils, it became apparent that they had not just one remarkably complete dinosaur, but several. Douglass called it a “beautiful sight,” and CMNH director William Holland could barely contain his glee in his reports back to the Pittsburgh museum. Under Douglass’s management, CMNH crews worked at what became known as the Carnegie Quarry for 13 years. The dinosaur fossils were jumbled and often overlaid one another, so the excavators had to work on multiple skeletons simultaneously. The especially hard sandstone also slowed their work, and the team regularly resorted to huge horse-drawn plows and even dynamite to reach the fossils. Eventually railway tracks were installed to help transport blocks of sandstone out of the quarry.

In 1915, Holland successfully petitioned Woodrow Wilson to preserve the site as a national monument. CMNH crews continued to excavate until early 1923. At that point, their primary benefactor Andrew Carnegie had died, and funding for field work was dwindling. Other museums collected from the quarry periodically in the years that followed, but Douglass’s idea to contain the remaining fossils in an on-site museum was not realized until 1958.

The Mounts


CMNH Apatosaurus. Historic photo from McGinnis 1982; modern photo source.

Apatosaurus louisae – CM 3018

The CMNH Apatosaurus was the first dinosaur discovered at the Carnegie Quarry. After Douglass first spotted the articulated caudal vertebrae in August of 1909, his crew spent several months extracting the rest of the skeleton from the rocks. The excavation continued into early 1910, and by the time they were finished they had the most complete Apatosaurus ever found – a title the specimen holds to this day. Holland mounted the 77-foot skeleton alongside the museum’s Diplodocus in just three years, at the time a record for a sauropod mount.

Holland famously left his Apatosaurus headless for decades due to a disagreement with Henry Osborn of the American Museum of Natural History. Douglass recovered a skull that almost certainly belonged to the Apatosaurus, but Holland opted not to use it because it contradicted the sculpted head already in place on the AMNH Apatosaurus mount. After Holland’s death in 1932, museum staff quietly added a casted Camarasaurus skull as a placeholder. This was finally replaced with a proper Apatosaurus skull in 1979. More recently, the team at Phil Fraley Productions disassembled and restored the Apatosaurus, along with the rest of the classic CMNH dinosaurs. Since 2007, this specimen has been back on display in a more graceful modern pose.

Fancy fisheye photo.

AMNH Barosaurus. Source

Barosaurus lentus – AMNH 6341

When the CMNH team discovered this skeleton in 1912, they assumed it was yet another specimen of the well-known Diplodocus. It was harvested for parts, with portions sent to CMNH, the United States National Museum, and the University of Utah to supplement their displays. When the specimen turned out to be the more obscure sauropod Barosaurus, it languished in pieces for many years. Barnum Brown of AMNH was making a circuit of the fossil collections at various natural history museums when he rediscovered this specimen. Through a series of purchases and trades, the Barosaurus was reunited at AMNH in 1929.

Nevertheless, AMNH quickly abandoned plans to mount the Barosaurus – the museum already had a sauropod on display, and there wasn’t enough floor space for another one. It wouldn’t go on display until 1991, when Lowell Dingus conceived of the idea to mount the Barosaurus in a spectacular rearing pose as part of the renovation of the Theodore Roosevelt Rotunda. Peter May took on the project – one of the first mounts produced by his company Research Casting International. The resulting display, actually a cast, is the tallest free-standing dinosaur mount in the world.

ROM Barosaurus.

ROM Barosaurus. Source

Barosaurus lentus – ROM 3670

Douglass recovered a second partial Barosaurus skeleton in 1912, which consisted of a mostly complete torso and parts of each leg. It stayed in the CMNH collections for many years, until they traded it to the Royal Ontario Museum in 1962. ROM staff intended to mount the skeleton, but once again this was cancelled due to a lack of space. David Evans was developing a new ROM paleontology exhibit in 2007 when he learned that the museum had most of a Barosaurus sitting in its collections. With only weeks remaining before the exhibit’s opening, Evans tapped Research Casting International to mount the sauropod, supplemented with a replica neck and tail from the AMNH version.

Allosaurus fragilis – CM 11844

Several Allosaurus specimens are known from the Carnegie Quarry, but the one on display at CMNH is one of the largest. Douglass and his team excavated this 35-foot skeleton between 1913 and 1915. The mount was built in 1938. Although the specimen included a partial skull, the exhibit team swapped it with a cast of a more complete skull (also found in the Carnegie Quarry) from the collections of the University of Utah. This mount also includes casts of the arms of USNM 4734, an Allosaurus collected for O.C. Marsh.

Stegosaurus ungulatus – CM 11341

The CMNH Stegosaurus is a composite of several individuals excavated from the Carnegie Quarry between 1920 and 1922. Museum staff completed the 21 foot-long mount in 1940, using a skull cast from USNM 8612. Casts of this skeleton were distributed to several other museums at some point, one of which is on display at the University of Nebraska State Museum. Phil Fraley’s company remounted the CMNH original in 2007.

Carnegie Camarasaurus.

Carnegie Camarasaurus. Source

Camarasaurus lentus – CM 11338

This juvenile Camarasaurus is the most complete sauropod ever found. It is displayed as a relief mount almost exactly as it was discovered, with two exceptions. The left leg was swapped with a more complete one from another individual, and the tail was re-positioned to create a more aesthetically pleasing mount. Casts of this skeleton are displayed at museums throughout the United States, including Dinosaur National Monument, but the original is at CMNH. This specimen is also notable because its left scapula is preserved in its life position, making it a helpful model for skeletal reconstructions and exhibit mounts.

NMNH Camarasaurus. Photo by the author.

NMNH Camarasaurus. Photo by the author.

Camarasaurus lentus – USNM 13786

The second best Camarasaurus also comes from Carnegie Quarry, but it is a considerably larger individual. Only the tail and a few odds and ends were missing. CMNH kept the specimen for several years before trading it to USNM in 1933 for a set of Pliocene horse skeletons. Norman Boss prepared the specimen in full view of the public during the 1936 Texas Centennial Exposition – one of the first known examples of such an exhibit. The completed mount appeared at USNM in the 1950s, sporting the tail of another Camarasaurus. At over 30 feet long, this skeleton is one of the largest dinosaurs on display at the Smithsonian. Unfortunately, the death pose somewhat limits the effect. The Camarasaurus was taken off exhibit in late 2014 for conservation and remounting. When it returns, it will be standing on its feet for the first time in 150 million years, taking its rightful place as one of the museum’s most impressive dinosaurs.

DMNH Diplodocus. Source

DMNH Diplodocus. Source

Diplodocus longus – DMNH 1494

Since this Dipldodocus was found somewhat disarticulated, Douglass suggested that the carcass may have been twisted apart while rolling downstream. AMNH held on to this skeleton for some time before trading it to the Denver Museum of Nature and Science in 1936 for two mammoth skeletons. Preparator Phillip Reinheimer mounted the skeleton with the help of 40 workers assigned to the museum through the Works Progress Administration. Additional Diplodocus fossils collected by William DeWeese (actually the first dinosaur specimens acquired by the museum) were also used to complete the mount. The Diplodocus remained on view until 1989, when Ken Carpenter and others restored and remounted the sauropod, elevating its tail and making its neck sweep gracefully to the left. The improved mount has been on display since 1995.

CMNH Camptosaurus.

CMNH Camptosaurus. Historic photo from McGinnis 1982; modern photo source.

Camptosaurus aphanoecetes – CM 11337

Douglass found this controversial small ornithopod in 1922, and correctly matched it with an isolated leg several feet away. It was first identified as Camptosaurus medius, but in 2008 Ken Carpenter reassigned it to the new species C. aphanoecetes. A 2011 phylogenic study by Andrew McDonald moved this specimen to a new genus, Uteodon. Carpenter, however, asserts that McDonald’s analysis was based on an incorrectly associated Dryosaurus braincase.

CMNH staff assembled the fossils into a relief mount in 1940. The skull, hindfeet, and tail were all sculpted. During the 2007 renovation, the Phil Fraley Productions team extracted the fossils from the plaster slab, even managing to preserve the delicate ossified dorsal tendons. They then created a new, three-dimensional mount, which features a revised replica skull.

Modern photo by the author.

CMNH Dryosaurus. Historic photo from McGinnis 1982; modern photo by the author.

Dryosaurus altus – CM 3392

This Dryosaurus skeleton is the most complete of several collected at Dinosaur National Monument. The tail is missing, and given the completeness of the rest of the skeleton it may well have been destroyed when Douglass’s crew was blasting through rock to get to the bone layer. The Dryosaurus entered the CMNH collections in 1922, and was assembled as a 9 foot-long relief mount in 1940. In 2007, Fraley’s team removed the fossils from the plaster matrix, and just as they did with the Camptosaurus, constructed a standing mount. To date, this is the only mounted Dryosaurus specimen in the world. It is displayed alongside a juvenile Ceratosaurus cast acquired from Western Paleontological Laboratories.

National Museum of Natural History in Washington, DC.

NMNH Diplodocus. Photo by the author.

Diplodocus sp. – USNM 10865

The National Museum of Natural History’s Diplodocus was one of the last articulated skeletons removed from the Carnegie Quarry. When the CMNH crew closed up shop, Charles Gilmore of the Smithsonian moved in to recover one of the sauropod skeletons Douglass left behind. In 1923, Gilmore’s team excavated a partial Diplodocus, and also cherry-picked a few extra bones from an adjacent specimen. The process of mounting the skeleton at USNM took six years of continuous work, and Gilmore would later describe it as the most ambitious undertaking his department hadever attempted. The 70-foot Diplodocus mount was completed in 1931, and remained unchanged for more than 80 years. It was finally taken down in December 2014, and will return in a new pose in 2019.

Addendum: Mike Taylor recently called attention to a gorgeous map of the entire deposit prepared by Ken Carpenter, which was what prompted this post. Check it out here.


Carpenter, K. (2013). History, Sedimentology, and Taphonomy of the Carnegie Quarry, Dinosaur National Monument, Utah. Annals of the Carnegie Museum 81:3:153-232.

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

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.

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


Filed under AMNH, CMNH, collections, dinosaurs, exhibits, field work, fossil mounts, history of science, museums, NMNH, ornithopods, sauropods, theropods, thyreophorans