Tag Archives: amnh

Real or cast? If only it were that simple!

Norman Boss Brachyceratops courtesy Smithsonian archives

Norman Boss assembles  a “Brachyceratops” mount. White bones and portions thereof are sculpted. Image courtesy of the Smithsonian Institution Archives.

Back in January, London’s Natural History Museum incited a flurry of debate when it announced that Dippy, the Diplodocus skeleton that has graced the museum’s entrance hall for decades, will soon be retired and replaced with a blue whale. One of the recurring arguments in favor of the change has been that Dippy is not an original specimen – it’s a cast, or as some commentators have called it, “a fake.” As I argued last month, referring to a fossil cast in this way is a flagrant misrepresentation. An excellent post by Liz Martin covers this in more detail – “fake” implies deception, or something invented outright. Fossil casts are nothing of the sort. They are exact replicas of fossils, and they could not exist without the original specimens they are based on.

Nevertheless, the idea that fossil mounts are either original bones or casts is a bit of a false dichotomy. I’m as guilty as anyone of propagating this myth – it’s a simple way to assuage the fears of museum visitors that the fossil skeletons on display aren’t real. The truth is that most mounts include some amount of straight-up sculpted material. After all, the fossilized remains of vertebrate animals, particularly large ones, are almost never found articulated or anywhere near complete. The specimens chosen for museum mounts are among the absolute best available, but even they are not perfect. For instance, the NHM Dippy (actually one of many) is mostly a cast of a single Diplodocus specimen held at the Carnegie Museum of Natural History, but the forelimbs were reconstructed. When the mount was assembled, no Diplodocus forelimb material of comparable size was available, so Arthur Coggeshall and colleagues sculpted some based on smaller specimens.

Sculpted feet

The sculpted feet of the AMNH Tyrannosaurus. Photo by the author.

From Hadrosaurus, the first mounted dinosaur skeleton, to modern reconstructions like Anzu, fossil mounts as we know them would not be possible without some amount of informed reconstruction. Take the iconic Tyrannosaurus rex mount at the American Museum of Natural History, assembled in 1915. The skeleton is a composite of two T. rex specimens, neither of which included any of the bones of the feet. Rather than creating a skeleton that stopped short at the ankles, Adam Herman sculpted a set of feet based on Allosaurus, another large meat-eating dinosaur. When Tyrannosaurus feet were eventually discovered, the allosaur-inspired feet turned out to be a little too bulky – tyrannosaurs actually had relatively long, gracile toes. But it’s not like T. rex turned out to have hooves or wheels. In most respects, from the basic three-toed arrangement to the shape and position of each individual bone, Hermann’s hypothesized tyrannosaur feet were spot-on. In fact, they were so close that the museum didn’t bother updating them when the skeleton was remounted in 1995.

The sculpted portions of fossil mounts aren’t wild speculation. They are very reasonable hypotheses based on a solid understanding of skeletal anatomy. As anatomist Georges Cuvier wrote in 1798:

Today comparative anatomy has reached such a point of perfection that, after inspecting a single bone, one can often determine the class, and sometimes even the genus of the animal to which it belonged…this is because the number, direction, and shape of the bones that compose each part of an animal’s body are always in a necessary relation to all the other parts, in such a way that – up to a point – one can infer the whole from any one of them and vice versa.

Cuvier’s principle of the correlation of parts – the idea that all backboned animals are built on the same basic body plan – is fundamental to the science of paleontology. If we have the right forelimb of an animal, we know that it had a mirror-image left forelimb. If we find a skeleton with it’s skull missing, we can still be confident that it had a head. What’s more, specialists can often recognize the group an animal belongs to (and sometimes the species) from just a few bones or teeth. Salamander vertebrae have a characteristic hourglass shape. Frog limb bones have “double-barreled” cavities in cross section. Marsupial teeth have a stylar shelf. New world monkeys have an extra premolar in each quadrant of the mouth. With enough specialized knowledge of related taxa, it is entirely possible to produce an educated reconstruction of most any animal from a minority of its skeleton.

How much is too much?

Argentinosaurus and Giganotosaurus at the Fernbank Museum of Natural History. Source

But as far as mounted skeletons in museums go, how far can we take this? Is it reasonable to build a standing mount when only 50% of the skeleton is definitively known? What about 30%? 10%? By bone count, that’s about the percentage of fossils ever found from the sauropod Argentinosaurus. And yet, the Fernbank Museum in Atlanta has a (rather spectacular) Argentinosaurus mount in its lobby. The whole thing is, of course, a fiberglass sculpture, dutifully based on better-known relatives. This mount is probably a fair reconstruction of what a complete Argentinosaurus skeleton would look like (although see this list of inaccuracies at Paleoking), but some still might consider it misleading. Your mileage may vary.

Museums generally do a good job labeling reconstructions. In particular, The Carnegie Museum and the Royal Ontario Museum are to be commended for posting charts alongside mounted skeletons that show which bones are original, which are casts, and which are reconstructions. In other cases, a little more transparency would not be unwelcome. For example, the four skulls below appear to include at least as much plaster reconstruction as bone, but they are all labeled as original specimens.

Photos by the author.

Four heavily-reconstructed fossil skulls at AMNH. Clockwise from top: Eryops, Indricotherium, Ophiacodon, and Triceratops. Photos by the author.

This is ultimately more of a philosophical question than a scientific one. Museum mounts, regardless of the amount of sculpted material, are usually well-supported reconstructions of the animal in question. If new information shows that a mount is wrong – as sometimes happens – staff are undoubtedly aware and will correct it as soon as funding and bureaucracy allow (granted, that can take decades). But as I’ve argued before, fossil mounts are unique among museum exhibits in that they are both the specimens and the interpretive context. They are hypotheses, but are presented (or at least understood) as straightforward truth. With this paradox in mind, how much is a museum ethically obligated to share about a mount’s creation? How can we do this without spurring visitors to use the dreaded f-word?

Comments are open, as always, and I’d be thrilled to hear what readers think.

11 Comments

Filed under AMNH, anatomy, dinosaurs, fossil mounts, mammals, museums, NHM, reptiles, sauropods, science communication, theropods

Framing Fossil Exhibits: Phylogeny

This is the third part of an on-again, off-again series about organizational and interpretive approaches in large-scale paleontology exhibits (see the introduction and walk through time entries). This time, I’ll be discussing exhibits arranged according to phylogenetics – that is, the evolutionary relationships among living things. Natural history museums have displayed specimens according to their place on the tree of life since the days of Charles Wilson Peale, and more than any other organizational scheme, phylogeny is the way biologists think about the living world. Perhaps unsurprisingly, this arrangement was more common in the past, when exhibits were typically designed by and for experts. Examples of these old-school displays include the fossil mammal gallery at the Peabody Museum of Natural History and the paleontology halls at the University of Kansas Natural History Museum (neither has been thoroughly overhauled since the 1950s).

peabody mammals

The jargon-heavy signage in the Peabody Museum’s classic fossil mammal exhibit is probably ignored by most visitors. Photo by the author.

Modern natural history museums rarely attempt phylogenetic exhibits. In vertebrate paleontology, an understanding of the evolutionary relationships of animals as identified via minute anatomical details is fundamental to our science. However, most people simply don’t think about the world in this way. For example, I was halfway through my first semester teaching an undergraduate anatomy course when I realized that most of the class didn’t really understand what a mammal is. The students were familiar with the word “mammal” and could provide some examples, but they couldn’t articulate what sets mammals apart from other animals, and the relationship of mammals to other vertebrates within the tree of life was all new to them. It’s easy to forget that even the most basic elements of evolutionary classification are specialized knowledge, even among biology students.

Describing the history of life on Earth chronologically is relatively easy—museum visitors intuitively understand the forward progression of time. But scientific classification (as opposed to colloquial categorization) requires a lot of explanation up front, and it’s easy to overwhelm an audience with jargon. While not impossible (see Neil Shubin’s masterful Your Inner Fish), it is very difficult to explain phylogeny to a general audience in a relatable and approachable way.

In 1995, the American Museum of Natural History attempted to do just that with the most recent renovation of its historic 4th floor fossil halls. This evolutionary arrangement was a major change for AMNH, since this space had a “walk through time” layout for most of the 20th century. In the accompanying book Discovering Dinosaurs in the American Museum of Natural History, curators Norell, Gaffney, and Dingus explain that phylogenetics (and the cladistic methodology in particular) is the only way to approach the study of prehistoric life in an objective way. Patterns of evolutionary relationships revealed by cladistic analyses are hard evidence in a field of study traditionally characterized by idle speculation. Norell and colleagues argue that the new exhibit arrangement shows visitors the credibility and scientific rigor behind modern paleontology.

4th floor of AMNH.

Map of the fossil halls on the 4th floor of AMNH. Source

Communicating the rigorous and trustworthy nature of scientific conclusions is a worthy goal, and the choice to ground the AMNH exhibit in this way seems almost prophetic given the litany of speculation-heavy paleontology “documentaries” that have proliferated in the years since it opened. Scientific rigor is definitely a running theme here – sign after sign explains that popularly depicted dinosaur behaviors like parental care and pack-hunting are largely untestable speculation. To a degree, this label copy takes the fun out of an undeniably fun subject, but I can appreciate the effort to legitimize paleontological science in the public eye. Overall, the AMNH exhibits represent an attempt to train visitors to look at fossils the way scientists do, and the phylogenetic layout is central to that goal.

In the exhibit, visitors are meant to walk through a cladogram of chordates. You’ll pass through large halls dedicated to broad groups like saurischian dinosaurs and advanced mammals, while visiting smaller cul-de-sacs that  represent narrower clades like ornithomimids and testudines. A central black path guides you through the evolution of life, and centrally-situated pillars along your route identify major evolutionary innovations, such as jaws or the ability to reproduce on land. The insanely comprehensive vertebrate fossil collections at AMNH make this institution uniquely capable of putting so much diversity on display (although non-tetrapods are woefully underrepresented). Meanwhile, an open floor plan allows you to spend as much or as little time in each area as you wish, and ample natural lighting goes a long way toward making it possible to study specimens in detail.

follow the path for now

Pillars mark major evolutionary milestones in the Hall of Vertebrate Origins. Photo by the author.

path disappears among dinosaurs

The evolutionary pathway becomes considerably less obvious among the dinosaurs. Photo by the author.

Nevertheless, I agree with Riley Black that the AMNH fossil halls don’t do the best job communicating the story of vertebrate evolution to their core audience. The underlying purpose of any exhibit structure is to provide meaning and context for objects – to help visitors see them as more than neat things to look at. According to visitor surveys, the default mode of understanding for most people passing through a paleontology exhibit is what I’ve been calling “dinosaur pageantry.” After seeing the exhibit, most visitors will recall a list of cool skeletons they saw. A few might consider which ones are meat-eaters and which ones are plant-eaters, but without further prompting that’s all we can usually expect from non-specialists. It’s the museum’s job to give visitors the intellectual tools to contextualize those fossils in a more sophisticated way, but there’s a fine line to walk. Provide too little information and nobody learns anything, but provide too much and the content is ignored. Unfortunately, the AMNH exhibits fall into the “overkill” category.

As discussed, phylogeny is complicated, often counter-intuitive, and largely unfamiliar to many visitors. To overcome this, the AMNH designers rely on a fairly long orientation film, which introduces the concept of categorizing organisms based on shared derived characteristics. There are a few problems with this. First there’s the film itself, which dives right into the traits that characterize different groups – like the stirrup-shaped stapes of derived mammals and the temporal fenestrae of archosaurs – without explaining why these traits are significant. To a layperson, these probably seem like really inconsequential things to hang a whole group on. The video also presents a cladogram of vertebrates without explaining how to read it. As Torrens and Barahona demonstrate, interpreting a phylogenetic tree is a specialized skill that many natural history museum visitors lack. Second, I saw no incentive or instruction to actually start my visit to the 4th floor in the orientation hall. There are no less than four entrances to the fossil exhibits, so many visitors won’t know there is an orientation film (I sure didn’t) until they’re halfway through the galleries. Finally, there’s the reliance on media in general: do we really want visitors to spend even a portion of their time in an exhibit full of real fossils watching a video in a darkened room? Telling visitors what to think in a narrated video is easy, but it’s not nearly as meaningful as showing them the same concept with specimens (or better yet, coaxing them to reach conclusions themselves).

Hall of Saurischian Dinosaurs, American Museum of Natural History. Photo by the author.

Iconic mounts in the Hall of Saurischian Dinosaurs are iconic. Photo by the author.

Within the actual fossil halls, interpretation remains stubbornly unapproachable. For example, the sign introducing proboscidians tells visitors that this group is defined primarily by eye sockets located near the snout. An observant visitor might wonder why scientists rely on such an obscure detail, as opposed to the obvious trunks and tusks. There’s a good teaching moment there concerning why some characteristics might face more selection pressure (and thus change more radically) than others, but instead visitors are only offered esoteric statements. Relatedly, the exhibit does little to prioritize information. Most label text is quite small, and there’s a lot of it. Compare this to Evolving Planet at the Field Museum, where there is a clear hierarchy of headings and sub-headings. Visitors can read the main point of a display without even stopping, and parents can quickly find relevant information to answer their charges’ questions (rather than making something up).

Evolving Planet also compares favorably to the AMNH fossil halls in its informative aesthetics and spatial logic. At FMNH, walls and signs in each section are distinctly color-coded, making transitions obvious and intuitive. Likewise, consistent iconography  – such as the mass extinction zones – helps visitors match recurring themes and topics throughout the exhibit. AMNH, in contrast, has a uniform glass and white-walled Apple Store aesthetic. It’s visually appealing, but doesn’t do much to help visitors navigate the space in a meaningful way.

edentates aren't real

Phylogenetic interpretations change quickly – Edentata is no longer considered a natural group. Photo by the author.

The phylogenetic layout introduces a number of other unique interpretive challenges. Since there is no temporal axis,  it’s often unclear whether the lineage in a particular cul-de-sac cluster went extinct, continued on, or gave rise to another group elsewhere in the exhibit. Visitors that want to know which animals lived contemporaneously are out of luck. Meanwhile, the exhibit sometimes uses modern animal skeletons to fill out displays where fossil examples are limited, such as bats and primates. While these are labeled, the text is too small to be seen from a distance. The evolutionary organization is also burdened by the fact that phylogenetics is a fast-moving and often changing field of study. While the order of geologic time periods will never change, the 20 year-old displays at AMNH are already out of date in several details. For example, there is a cul-de-sac devoted to edentates, which is now considered polyphyletic, and a cladogram in the Hall of Saurischian Dinosaurs incorrectly places tyrannosaurids among the carnosaurs.

Cows and broken videos

Glass architecture lets visitors see through displays and get a sense of what lies beyond. Photo by the author.

Neat comparison of mammal teeth. Too bad there's no obvious label.

This display is a great example of the diversity in mammal teeth, but it’s a confusing centerpiece for the Hall of Primitive Mammals. Photo by the author.

The AMNH fossil exhibits excel in many respects, chiefly in the amazing diversity and quantity of specimens on display. The exhibit throws a lot of good science at visitors, but falters in explaining why it matters. The point of all this is not to nit-pick the design choices at AMNH, but to reiterate that phylogenetically-arranged fossil exhibits are really hard to pull off. This is not the most intuitive way to introduce the history of life, or even the process of evolution. With so much background to cover, perhaps a more structured and linear layout would be better. In fact, a lot of my issues with the AMNH fossil exhibits seem to stem from a disconnect between the phylogenetic interpretive content and the wide-open aesthetics. Open exhibits can be great, but in this case it hinders the learning opportunities for self-guided groups of visitors. It’s difficult to imagine a typical visitor, arriving with their family or another mixed-age group, having the patience to make sense of it all. Regrettably, such visitors default to the dinosaur pageantry level of understanding, making all the work invested in creating a meaningful exhibit space for naught.

References

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

Torrens, E. and Barahona, A. (2012). Why are Some Evolutionary Trees in Natural History Museums Prone to Being Misinterpreted? Evolution: Education and Outreach 1-25.

14 Comments

Filed under AMNH, dinosaurs, exhibits, fish, FMNH, fossil mounts, mammals, museums, opinion, reptiles, reviews, systematics

The World’s Largest Dinosaurs (AMNH Part 1)

I spent the weekend in New York, and was able to spend a full day at the American Museum of Natural History. I’m a fan of New York, it’s just brimming with culture and has a neighborliness that one doesn’t see many other places. It had been much too long since I had been there, and even longer since I had been to AMNH. There’s a fair bit of brain dumping I’d like to accomplish on the topic of the museum, so I’ll probably  be posting thoughts on the  permanent paleobiology galleries and the mobile app fairly soon. For now, however, I really need to take a moment to gush about The World’s Largest Dinosaurs.

A typical dinosaur exhibit is based on the spectacle of the mounted skeletons. The curtain is raised on the strange and spectacularly large dinosaur bones, everybody oohs and ahhs, and that is all most/many visitors get out of it. Moreover, people leave (and probably came in with) the impression that paleontologists are people who dig up dinosaur bones and then put them on display. Such is not the case with The World’s Largest Dinosaurs, a new temporary exhibit at AMNH.

Life-size Mamenchisaurus. From http://gothamist.com.

The World’s Largest Dinosaurs is unique because it is not focused on skeletal mounts. There are no mounts to speak of in the gallery, and in fact, there are very few fossils on display at all. This exhibit provides a window into what vertebrate paleontologists do after they dig up the bones. Specifically, it is about sauropod biology. There has been a lot of really fascinating research into sauropod biology in the last 10-15 years, asking and answering questions such as, how did they carry all that weight? How did they reproduce? How did they get enough to eat? And of course, what’s the deal with those pneumatic bones? These questions are all explored in this exhibit.

A crappy image of an interactive display.

The layout of The World’s Largest Dinosaurs is very effective. Visitors are oriented in a narrow space that clearly lays out the topic at hand. Using skeletons of modern animals as comparisons, the questions that the very existence of sauropods raise are introduced to visitors (i.e., how did they get away with being so effin big?). Once the question is laid out, the exhibit opens up into a large space with many stations that address different research questions. The “ooh and ahh” factor is covered by a life-size model of a Mamenchisaurus in the center of the gallery, which doubles as a projection screen: animations of the circulatory, respritory and reproductive systems are displayed right on the model, accompanied by narration (see below).

Mamenchisaurus projection screen. From http://gothamist.com.

I was at AMNH on what turned out to be a very crowded day (no surprise, it was a rainy day on a holiday weekend), but I managed to get into the day’s earliest time slot, before it got too packed. When I was there at least, it was quiet enough for people to see the exhibits, and to get ahold of the interactives. As such, I observed people around me engaging with and understanding the material. Kids were working through the problems presented in the exhibit, despite the attempts of their parents to dumb down their experience and herd them through faster. The non-paleo people I were interested enough to read just about everything. Importantly, I heard no complaints that there weren’t many fossils on display. This is interesting, given how vocal some museum visitors can be about the exhibition of casts. Evidently, The World’s Largest Dinosaurs succeeded in entertaining and educating people without traditional mounted skeletons. I think this could potentially be a very big deal, and could cause museums to rethink the way paleontology exhibits are designed.

1 Comment

Filed under AMNH, dinosaurs, museums, reviews, science communication