Tag Archives: education

December 21, 2016 · 9:30 am

Phylogenetics is Moon Man Talk

Phylogenetics is the study of the evolutionary history and relationships among extant and extinct organisms. More than any other organizational scheme, this is the way biologists think about the living world. In vertebrate paleontology in particular, an understanding of the evolutionary relationships of animals as identified via minute anatomical details is absolutely fundamental to our science. One might even argue that most new discoveries and inferences in this field are meaningless without some knowledge of the basic shape of the tree of life.

I’ve spent about eight years so far teaching science in museums, parks, and classrooms. And based on my anecdotal experience, most discussion of phylogeny comes across as incomprehensible babble to a plurality of people. For instance, one of the most commonly used definitions of “dinosaur” among paleontologists is “the most recent common ancestor of Triceratops and modern birds, and all it’s descendants” (there’s also the similar “most recent common ancestor of Megalosaurus and Iguanodon, and all it’s descendants”). This definition is not meaningful to most people. As evidence, I submit the following set of questions, all of which I have been asked by intelligent and well-meaning adults:

Did whales and dolphins evolve from marine reptiles?
Did giraffes evolve from sauropods?
Are [dromaeosaurs] related to cats?
Are dinosaurs related to sharks?
How can birds be dinosaurs if dinosaurs are reptiles?
Did the plant-eating dinosaurs evolve into mammals?
Are bats a kind of bird?
Are pterodactyls a kind of bird?

I don’t mean to ridicule or disparage people for asking these questions. Again, these all come from educated adults – museum and park visitors, undergraduate students, T.A.s, and at least one veterinarian! While these questions clearly show unfamiliarity with evolutionary relationships and how evolution works in general, they also show an effort to build a logical framework when none is available. For example, when a person asks if whales are descended from marine reptiles, he or she is hypothesizing that all large marine animals are related. This is incorrect, but it’s a sensible connection to make (and one that past naturalists have certainly explored).

For science communicators, this deficit of phylogenetic understanding is a serious problem which continuously undermines attempts to interpret zoology and paleontology. For example, think about how little meaning a statement like “Dimetrodon isn’t a dinosaur” has to somebody who can’t articulate what a mammal is or what a dinosaur is, much less the evolutionary distance between both groups. This is what we should expect from most of our audience, which means there is always a lot of catch-up work to do when explaining something as simple as the basic identity of a given organism. By the time you’ve satisfactorily defined “dinosaur” (good luck with that), explained the synapsid-diapsid split, discussed the tree of extinct stem-mammals, and positioned each of these things in deep time, you’re five minutes deep into a lecture when all you were asked was “what is it?”

USNM 8635, a handsome non-dinosaur. Photo by the author.

How can we solve this conundrum? The first step is to divide the issue into a number of smaller problems:

People don’t understand the fundamentals of how evolution works
People are unfamiliar with basic vertebrate classification
People lack knowledge of key evolutionary events through deep time
People don’t understand what traits are significant when assessing evolutionary relationships

The first problem is well known and has been discussed in-depth elsewhere (e.g. MacFadden et al. 2007, Spiegel et al. 2006, Spiegel et al. 2012), so I’m going to breeze over it and focus on the other three.

Basic Vertebrate Classification

It’s easy to toss out words like “mammal”, “reptile”, and “amphibian”, and take for granted that your audience will know what they mean. But even the most basic elements of vertebrate classification are specialized knowledge, and science communicators would do well to remember it. When I was teaching an undergraduate human anatomy course, I found that most of the class was familiar with the word “mammal”, and could name some examples. However, the students 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.

I think this is fairly typical, even among individuals with a background in biology. People are introduced to these categories in grade school, and you’d be hard-pressed to find somebody who couldn’t tell you whether (say) a cat is a mammal or a reptile. What is missing is what that actually means. We can’t assume that just because somebody knows a cat is a mammal, they know that fur and milk glands (much less auditory ossicles, a solid mandible, and heteromorphic teeth) are things to look for when categorizing mammals. They also may not know that “mammal” is an evolutionary group – that all the animals that fall under this banner are more closely related to each other than they are to anything else. No mammal is going to spontaneously become a bird or a fish. This is obvious to specialists, but not to most of our audience.

Evolutionary History Through Deep Time

The situation is further complicated by the element of time. Somebody may know that a modern cat and lizard differ in several fundamental ways, but do they know that both groups still evolved from a common ancestor? Or that said ancestor lived more than 300 million years ago? Unfortunately, much of the public would appear to lack any knowledge of how the past is related to the present. I’ve had visitors insist on calling fossil turtles “dinosaur turtles” and Teleoceras a “rhino-saur.” For them, extinct animals (all labeled “dinosaurs”) are a category all their own, wholly independent from the categories that describe modern animals.

For specialists, it’s obvious that modern animals exist within a continuum that extends into the deep past. It’s also obvious that groups like “mammals” and “reptiles” had starting points, and are embedded within larger, more ancient groups. None of this can be considered common knowledge, but it’s critical to any discussion about the identity or categorization of a given taxon.

Box diagrams are a simple and intuitive way to ground students’ understanding of the diversity of life.

How can educators hope to cover so much ground without confusing, distracting, or alienating their audiences? One option is to use a cladogram, or evolutionary tree. Trees are absolutely the most precise and accurate way to portray relationships over time, but as Torrens and Barahona demonstrate, they are regularly misinterpreted by the public. When I’m dealing with a general audience, I prefer box diagrams like the one above. Boxes within boxes show tiers of relatedness in a way that is more intuitive and easily understood than a tree. Box diagrams allow educators to cover a lot of unfamiliar ground quickly, and it’s easy to test visitors’ comprehension by asking them to point to where an example taxon should be placed. While this visualization of vertebrate relationships lacks a time axis, people can at least grasp the relative order in which each group evolved (fish before amphibians, amphibians before reptiles and mammals, etc).

How Scientists Discover Evolutionary Relationships

Going back to the list of misguided questions at the top of this post, we can generally surmise the thought process that led to each inquiry. The person who asked if whales and marine reptiles are related was classifying based on shared habitat. The person who asked if giraffes evolved from sauropods was classifying based on similar body shape. We can also see classifications based on diet, and based on shared activities, like flight or attacking prey with clawed feet. All these questions reflect a misunderstanding of what kinds of traits researchers look for when working out evolutionary relationships. So how do we quickly and clearly explain which traits are relevant, and which ones are not?

This is a tricky problem, and one I have not found a perfect solution to. The most important distinction is between plesiomorphic and apomorphic traits: plesiomorphic traits are inherited from an ancestral form, while apomorphic traits are novel developments. Put simply, working out a phylogenetic tree is all about grouping organisms based on shared apomorphies. The more apomorphic traits between two species, the more closely related they are. Once introduced, this is a fairly intuitive distinction. You don’t even need to use the jargon – “old traits” and “new traits” will often suffice. Going back to our problem of defining Dimetrodon, we can clarify that the lizardy shape and general toothiness are “old traits” – so they don’t tell us much about what the animal actually is. Instead, scientists look at “new traits”, like the number of postorbital fenestrae, to work out Dimetrodon‘s evolutionary affinities.

All of this is a long-winded way of saying that relating phylogeny to the public is challenging, but very important. Too often, science educators assume visitors have more background than they do, and the discussion comes across as so much moon man talk. Alternatively, educators push past complicated parts too quickly, which leads to confusion or misunderstanding. Ultimately, being a good educator comes down to two things: knowing your content and knowing your audience. Both are equally important, and both need to be practiced and refined in equal measure to ensure successful communication.

References

Macfadden, B.J., Dunckel, B.A., Ellis, S., Dierking, L.D., Abraham-Silver, L., Kisiel, J., and Koke, J. 2007. BioScience 57:10:875-882.

Spiegal, A.N., Evans, E.M., Gram, W., and Diamond, J. 2006. Museums and Social Issues 1:1:69-86.

Spiegel, A.N., Evans, E.M., Frazier, B., Hazel, A., Tare, M., Gram, W., and Diamond, J. 2012. Changing Museum Visitors’ Conceptions of Evolution. Evolution: Education and Outreach 5:1:43-61.

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.

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Filed under education, opinion, science communication, systematics

Tagged as education, paleontology, science communication, scientific literacy, systematics

September 13, 2016 · 2:55 pm

A Game Changer?

Today, Google and 60 partner museums unveiled the new natural history arm of the Google Cultural Institute. Launched in 2011, the Cultural Institute is an effort to make culturally significant material accessible online. Up until this point, the primary focus has been on art and history. In conjunction with museums and other institutions around the world, Google has been uploading millions of images, archival documents, and virtual walkthroughs of significant places. The natural history project offers more of the same, but with 100% more dinosaurs.

I had no idea this was in the works, nor do I know much beyond what is said in the press release. After spending much of this morning exploring the site, however, you can color me impressed. The sheer amount of content is overwhelming: 300,000 annotated specimen photos, virtual walkthroughs of 50 museums, and 184 multimedia presentations on topics both general (cabinets of curiosities) and esoteric (native plants and fish of Korea). Unfortunately, accessing this content can be a bit of a chore. I was often confused by the user interface, and found many of the most interesting or useful items by accident.

Somewhere in the Ancient Americas exhibit at the Field Museum of Natural History. Google Cultural Institute

For me, the museum walkthroughs are the clear highlight. Using Google’s Street View technology, users can explore the included museums and get surprisingly close to individual displays. Some of these “virtual tours” are frustratingly limited to a few corridors between exhibits, but others provide darn near the full experience of actually being there. Of the museum walkthroughs I’ve looked at so far, the National Museum of Natural History and Berlin’s Museum für Naturkunde are particular standouts in this regard. A handful of museums have had virtual tours available online since at least the early 2000s, but this is the first time I’ve seen the concept escape the gimmick stage and become something potentially useful.

The quality of the multimedia presentations (“virtual exhibits”, if you must) is a bit mixed. The best ones make specific use of the partner museums’ collections, highlighting the scientific, cultural, or historical significance of particular objects. These presentations provide curatorial expertise and novel insights that are not easily found elsewhere. Other presentations, however, are frustratingly generalized, and don’t include much content that one couldn’t get from skimming a Wikipedia article.

yawn, another cgi sauropod. I'd rather see the mount.

Yet another middling CGI dinosaur. Yay, I guess? Google Cultural Institute

I would include the site’s flagship attractions – narrated 360-degree tours of selected exhibit halls – in the second camp. These three short videos each feature an exhibit that “comes to life” with the help of some acceptable-but-not-spectacular CGI. Take the video about the Giraffatitan at the Museum für Naturkunde. It’s awesome to be able to look all around the hall, but most of the video is taken up by an animated version of the dinosaur that doesn’t accomplish anything it’s Jurassic Park counterpart didn’t 23 years ago. The video starts to tell some interesting stories – convergent evolution between sauropods and giraffes, the rate of extinction caused by human activities far outpaces normal background extinction – but the goofy CGI Giraffatitan is very much in the way. Museums have so many strengths, so I’ll never understand the impulse to rely on things like animated dinosaurs that a) their audience can see elsewhere and b) Hollywood will always be able to do better.

A great deal of content to be found by the bold.

A great deal of content can be found by the bold. Google Cultural Institute

All in all, the new natural history project at the Google Cultural Institute is a very impressive starting point. Nevertheless, my optimism is tempered by the fact that the web is littered with apps and mini-websites developed by museums, then almost immediately abandoned. Too often, digital projects are taken on without a clear idea of who will continue to update it, what need is being addressed, or even who the website or app is for. The real test will be whether Google and the partner museums will continue to support the Cultural Institute with new content. This has been a recurring problem with museums’ digital endeavors, but perhaps the collaboration with Google (and its extensive infrastructure) will help.

Moreover, accessibility is an admirable goal, but there is a very wide gap between putting stuff online and creating something that lots of people (teachers, students, people who don’t live near museums) actually want to use. I’m encouraged by the range of material on the Cultural Institute site. Some content is fairly general, perhaps suitable for a 3rd grade science report, while other content is far more in-depth. I will be very curious to see what the public ends up using, and for what purpose. It would also be neat to see if this ended up being the start of a truly global digital collection, useful for educators and researchers alike. We’ll see if the Cultural Institute ends up being the catalyst that finally makes digital museums happen!

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Filed under collections, dinosaurs, education, exhibits, museums, sauropods, science communication

Tagged as digital, education, Google Cultural Institute, museums, natural history museums, science communication, science education

July 10, 2015 · 12:13 pm

Framing Fossil Exhibits: Environmental Change

Over the past few months, I’ve been writing about the strengths and weaknesses of various large-scale paleontology exhibits from an educational standpoint. Check out the Introduction, Walk Through Time, Phylogeny, and Habitat Immersion posts if you’d like to catch up. I’ll wrap up this series for the time being with a look at two upcoming renovations of classic fossil displays, which appear to have converged on similar aesthetic, organizational, and interpretive approaches.

First up is the Peabody Museum of Natural History, where the Great Hall of Dinosaurs and adjacent Hall of Mammal Evolution have seen little modification since the 1950s. While the PMNH fossil galleries are fascinating as a time capsule of mid-century exhibit design, much of the content is rather dated and a thorough overhaul is sorely needed. PMNH staff started planning for the renovation in 2010, and I highly recommend Collections Manager Chris Norris’s blog posts on the process. Once the basic layout and concepts were in order, the museum hired the architectural firm Studio Joseph to prepare the images being used to promote the project. Fundraising is now underway, but an estimated completion date has yet to be announced.

Conceptual render of the Great Hall of Dinosaurs by Studio Joseph. Source

The big idea behind the new exhibit is the dynamic relationship between the biosphere and the Earth’s various other spheres (atmosphere, geosphere, hydrosphere, etc). The evolution of life on Earth did not occur in a vacuum, but as part of a continuously changing global system. This narrative does have a time axis – visitors will travel from the Permian at one end of the exhibit to the Quaternary at the other – but the precise divisions of geologic time are de-emphasized in favor of the broad environmental transitions that triggered evolutionary innovations. Examples might include the separation of continents during the Mesozoic, the diversification of flowering plants in the Cretaceous, or the massive climatic shift at the end of the Eocene. In this context, it’s more important that visitors understand (for example) that the Cenozoic was generally a transition from hot and wet to cold and dry (and the implications on mammalian evolution) than that they know the names and time spans of each epoch.

This approach contrasts sharply with traditional chronological exhibits, such as the Field Museum of Natural History’s “Evolving Planet.” The FMNH fossil galleries are extremely linear, and each geologic period is introduced with a set of easily-digested bullet points summarizing what happened during that time. Relatively tight spaces prevent visitors from seeing specimens from other time periods prematurely, and the galleries devoted to each period are color-coded to make them immediately distinct. According to Norris, this segmented presentation of the history of life obscures the large-scale transitions which transcend the somewhat arbitrary divisions of geologic time. As such, the new PMNH fossil halls will present the narrative holistically, encouraging visitors to track the underlying environmental trends that precipitated evolutionary change over time.

mammal hall concept art by Studio Joseph

Conceptual render of the Hall of Mammals by Studio Joseph. Source

As is immediately clear from the promotional images, the new exhibit will juxtapose a modern, wide-open aesthetic with elements of the museum’s past – specifically, the outdated but gorgeous Rudolph Zallinger murals. Both of these design elements tie directly to exhibit’s narrative themes. By breaking up the central dinosaur pedestal and eliminating the unsightly glass cases in the Mammal Hall, the exhibit designers have dramatically increased the available floor space and opened up new lines of sight. This should allow visitors to view each of the galleries comprehensively, rather than as a series of discreet segments. Meanwhile, the Zallinger murals will remain a celebrated part of the exhibits. These magnificent frescoes were painted between 1942 and 1967, and are among the most iconic images of prehistoric life ever created. Although the physiology of some of the animals is outdated, Zallinger was in other ways ahead of his time. Rather than giving the geologic periods hard borders, Zallinger artfully wove the sections together so that each one fades imperceptibly into the next. The viewer can see that the flora, fauna, and climate are changing over time, but it’s a gradient, not a ladder, which perfectly reflects the narrative of the new exhibit.

A conceptual render of Deinonychus and other Cretaceous fossils. Source

About 300 miles south of PMNH, the re-imagining of the fossil halls at the National Museum of Natural History is well underway. This building’s east wing has been home to paleontology displays since it opened in 1910 and has been updated several times, but this is the first time it has undergone a complete, wall-to-wall modernization. The old exhibits were formally closed on April 28th, 2014, and NMNH staff spent the following year removing thousands of specimens from the halls. With the fossils out of the way, the next step will be to restore the historic space to its original neoclassical glory. After that, the new exhibits and updated fossil mounts can be assembled in time for a 2019 re-opening.

Intriguingly, the planned design of the new National Fossil Hall is both thematically and aesthetically similar to the PMNH renovation, albeit on a grander scale. The National Fossil Hall’s narrative focus will be on large-scale environmental transitions over time, and how these changes drove the evolution of plants and animals. Like at PMNH, this will be accentuated by an open layout: false walls and barriers that have divided the space since the early 1960s will come down, allowing visitors to see clear across the spacious three-story hall. This airy aesthetic hearkens back to the Hall of Extinct Monsters, and like the restoration of the Zallinger murals at PMNH it represents an admirable celebration of the institution’s history.

Early conceptual render of the National Fossil Hall by Reich + Petch Source

One interpretive choice that will set the National Fossil Hall apart is the clustering of specimens on islands, or “pork chops”, as the were called early in development. Each pork chop represents North America at a particular period in time. While anchored by a few charismatic mounts, the pork chops will also include all manner of small animals, invertebrates, and plants that were part of that environment. In this way, the islands are self-contained mini exhibits, each one showing a complete ecosystem that existed at a particular time. Moving among the these displays, visitors should get a sense of how climate change and faunal interchange (among other phenomena) can completely transform an ecosystem over millions of years. They’ll also learn how certain organisms, like sauropods in the Jurassic or grass in the Neogene, can change landscapes and influence the evolution of contemporary plants and animals.

The emphasis on open spaces and freedom of movement is notable, because this is quite different from the linear exhibits of the late 20th century. In recent decades, exhibits have become increasingly structured, with specific learning goals and physical spaces designed to corral visitors through a carefully orchestrated narrative journey. Again, Evolving Planet at FMNH is an excellent example of this philosophy. The new National Fossil Hall is in some ways a push in the opposite direction – although it has a clear narrative and overarching message, visitors can roam through the exhibit as they please. I see the pork chop system as a way to have it both ways. Whether visitors work through the exhibit front to back or run straight to the T. rex in the center of the hall, then wander around at random, they’ll still be able to compare and contrast the different ecosystems and learn what the designers want them to learn.

Early concept art of the Jurassic “pork chop.” Image from The Last American Dinosaurs, NMNH.

More than anything else, what I expect to set the National Fossil Hall apart from peer exhibits will be its explicit connections to modern-day environmental crises. It’s worth quoting the Department of Paleobiology’s summary in full:

Visitors to the Museum will be able to explore how life, environments, and ecosystems have interacted to form and change our planet over billions of years. By discovering and harnessing the tools and methods paleobiologists use to study fossils, visitors will gain a deeper understanding of how the world works.

The distant past affects all of us today and will continue to do so in the future. How will climate change impact the natural world and our daily lives? How can we make informed choices about our ecosystems as individuals and as a species? How can we all become informed citizens of a changing planet?

We are in the midst of an extinction event of our own making. Anthropogenic climate change, habitat destruction, and invasive species are as dangerous as any asteroid, and will likely have profound effects on our own lives and livelihoods in the coming century. But while humans are undeniably the cause of the latest round of global changes, we also have the power to mitigate and manage their consequences. The study of fossils provides important contextual information – we can place modern organisms in an evolutionary context and understand their role in shaping the world as we know it, and we can see how organisms have responded to significant environmental overhauls in the distant past. The fossil record is in fact the only way to directly observe these things (as opposed to relying on models or actualistic experiments). As such, the new National Fossil Hall will make it clear that paleontology isn’t just about historical curiosity. The study of past life gives us a long view of the Earth’s biotic and abiotic systems, and helps us predict how they will respond to today’s environmental changes.

Concept drawing of the National Fossil Hall’s Cretaceous zone. In the old hall, the viewer would be standing at the base of the mezzanine stairs facing the rotunda. Source

With the modern climate crisis front and center, the new National Fossil Hall has the potential to be one of the most immediately relevant and important paleontology exhibits ever assembled*. This is significant, because as I lamented when I started this series, immediacy and relevance are not things that most museum visitors expect from fossil displays. While fossils, particularly the mounted skeletons of dinosaurs and other prehistoric animals, have been central to the identity of natural history museums since the late 19th century, most visitors don’t regard these exhibits as anything more than prehistoric pageantry. Visitor surveys consistently reveal that dinosaurs are seen as eye candy – monsters that might as well be from another planet. This is a shame, because dinosaurs and other prehistoric organisms were real parts of our own world, and we can learn much from them.

The new National Fossil Hall will be arranged in reverse chronological order – as visitors move accross the gallery, familiar elements of modern environments will be stripped away and the world will become an increasingly alien place. Source

And so we come full circle. What is the point of a museum exhibit**? Is it enough to provide visitors an opportunity to see cool objects and specimens? When we ask museumgoers what they want to see, they tell us “dinosaurs” or “fossils.” They don’t ask for compelling narratives or connections to big contemporary issues, and they don’t see their museum visit as an important way to bridge gaps in scientific literacy.

Still, it is of critical importance that we provide these narratives and connections. Even if we accept the fact that the very existence of a museum and the chance to see real specimens is a Good Thing, museums are still accountable to the public. Virtually all museums cite education as the primary purpose of their institution, and it’s imperative to live up to that. A museum should have a learning goal in mind, it should be able to prove that this message is coming across, and it should be able to articulate why its audience is better off for it. This is not necessarily easy – exhibits need to be relevant without being condescending or preachy. Exhibit designers need to understand their visitors as much as their content. They need to find a balance between feeding visitors information and providing a customizable experience for diverse audiences. As we have seen, not every exhibit succeeds, but my impression is that we’re getting better at it.

*It’s also notable that this climate change-focused exhibit will be on the national mall, given the ongoing politically-motivated opposition to climate science.

**Note that I’m referring specifically to public-facing exhibits. There are many good reasons why the ongoing maintenance of natural history collections is intrinsically valuable.

References

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. http://circle.ubc.ca/handle/2429/50177

Weil, S.E. (2002). Making Musueums Matter. Washington, DC: Smithsonian Books.

Werning, S. (2013). Why Paleontology Is Relevant. The Integrative Paleontologists. http://blogs.plos.org/paleo/2013/02/19/why-paleontology-is-relevant

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Filed under dinosaurs, education, exhibits, FMNH, museums, NMNH, opinion, PMNH, science communication

Tagged as education, evolution, exhibits, Extinct Monsters, museums, natural history museums, NMNH, paleontology, Peabody Museum, science communication, scientific literacy, Smithsonian

March 14, 2014 · 4:27 pm

What’s the deal with Astrodon?

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

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

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

The taxonomic history of Astrodon

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

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

Astrodon teeth are on the lower left.

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

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

Pleurocoelus elements. Image from NMNH Backyard Dinosaurs.

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

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

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

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

Creating a coherent picture of Astrodon

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

Both camarasaur and brachiosaur shaped Astrodon reconstructions are equally reasonable.

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

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

Teaching Astrodon

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

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

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

References

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

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

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

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

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

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

Drama and natural history

While running errands this morning a thought came to me: a natural history exhibit in a museum is a lot like a stage performance*. When watching a play, the viewer knows she is seeing a performance, but it willing to suspend disbelief so long as the fantasy is well-created. To varying degrees, most modern natural history exhibits engage in the same theatrical relationship with their audiences. Exhibits re-create reality within the museum environment, and visitors accept the performance as truth.

*Actually, I thought “movie” first, but theater is a better analogy because the actors are real and present.

A rather poignant picture of the CMNH zebra diorama. Source: amyboemig on flickr.

Habitat dioramas featuring taxidermied animals are the most obvious example. Dioramas like the lovely east African savannah scene at the Carnegie Museum of Natural History pictured above are exactingly detailed microcosms modeled after actual environments. The backdrops are typically based on photographs of real locations. The teams that collected the animal skins would also take samples of leaves and even molds of tree bark, in order to exhibit the ecosystem in toto. And of course, the mannequins on which the animal skins are mounted were sculpted by artists with a strong foundation in anatomical science. And yet, the diorama is clearly not real. Visitors know that they are not looking at an actual game reserve that has been somehow frozen in time. Many viewers might mistake the animals as being “stuffed” (they are in fact sculptures with tanned skins fitted onto them), but they still recognize some element of artifice. The animals clearly didn’t end up in the glass-enclosed box on their own accord. And yet, visitors accept the illusion, because they keep coming to museums to learn about the world around us.

The same holds true for most other displays. These dioramas at the New York State Museum are not literally historic Iroquois villages shrunk down to 1/20 scale. The Tyrannosaurus and Triceratops pictured below are not really fighting, nor did they die in a death struggle. Even the Apple Store-eque NMNH Hall of Mammals recreates natural behaviors against a sterile backdrop. Unless the museum is displaying completely decontextualized specimens lying prone on a shelf, there is some degree of theatricality in the exhibit.

Tyrannosaurus and Triceratops at the Children’s Museum of Indianapolis. Source.

The theater analogy begins to go astray, however, when we consider that the performances in natural history exhibits are informed by reality. For the most part, exhibit designers do not place specimens in completely fictitious scenarios; the theatrical element serves to illustrate something real. Perhaps exhibits are more akin to a movie “based on a true story.” But like those movies, there is an undeniable selectivity in how museum workers tell their stories. Why are the zebra in the CMNH diorama chilling amicably with wildebeest? That is certainly something that real zebra have been known to do, but zebra have also been known to drown lions, trample foals and chew on the cars of obnoxious tourists. For that matter, why does this diorama not include any sign of human pastoralists, who have lived in the same environment as these animals for thousands of years?

Exhibits have human authorship, just like any other document. The manner in which any specimen or object is displayed is inherently subjective, and there will always be emphasis and omissions, intentional or otherwise, that change the way the exhibit is interpreted. Before you misjudge me, dear reader, this is not an argument that there is no objective reality. I wouldn’t even say that it is impossible to understand and perceive objective reality. Scientists do it all the time. But when it comes time to communicate that information, we are creating something new, and choosing what we incorporate and how we express it. Getting back to my original point, we’re putting on a representational show. And that means that what we’re creating only works as long as our audience is willing to participate in the performance.

Part 3: In Which Ben Gets to the Point

I’ve spent a couple posts raining hate on the media’s portrayal of science and exuberantly praising science bloggers. I’d like to wrap this series up with a few suggestions for how the excellent science communication in blogs might be applied to other media, specifically museums. Science blogs currently reach a relatively small audience, but the strategies for science communication employed by bloggers can be utilized by media forms that attract far more people.

Museums occupy the lower middle range of visibility among science communication venues. America’s most-visited natural history museum, the National Museum of Natural History, had seven million visitors in 2009, a number which pales in comparison to the 431 million homes reached by the Discovery Channel, but which is considerably higher than the 500,000 2011 subscribers to Scientific American magazine. Nevertheless, museums require special recognition in that they are among the most trusted of media forms. 86% of Americans view museums as a trustworthy source of information, substantially higher than the number of Americans that trust books (61%), television (49%) or newspapers (41%). Since museums are blessed with such high public trust, the stakes are higher for museums to report information accurately.

The New Museums

The museum field has undergone a significant revolution since the 1970s, trading its traditionally academic leadership for an audience-focused and education-based model. This change is beneficial because museums are now beholden to serving the needs of the public, and are trying (and occasionally succeeding) to serve increasingly diverse audiences. Visitors are now seen as active participants in the learning process, rather than passive spectators. This new paradigm has, however, made museums vulnerable to the same pitfalls that plague other media forms. Some in the museum field have noted that concern for public interests has been in some cases led astray by devotion to entertainment. Many newer exhibits sacrifice scholarship and educational value for gimmicks and sensationalism, not unlike the practices in science journalism.

An additional hurdle facing museums is the difficulty of communicating science through objects. Museums are based around objects, but science is based on ideas and concepts. Traditionally, science exhibits would place a spotlight on spectacular objects, but would communicate very little information about why those objects are important and what scientists can learn from them. For example, a paleontology exhibit is typically centered on the enormous mounted skeletons of dinosaurs, but visitors can only learn so much from this kind of display. The audience will surely be impressed by the size of the skeletons, but will leave without understanding what those skeletons tell us about the age of the earth, the evolution and diversity of life, and the place of humans in the natural world. The lack of science in science museums is an oversight that has unfortunately stood the test of time, and museums would do well to reconsider their approach to science communication.

New Strategies

Museum workers are moving toward an audience-centered institutional mission, but have struggled to do so without resorting to the same non-educational sensationalism seen in attempts at science communication in other media. Science blogs, however, are achieving this goal right now: they foster dialogue between scientists and laypeople, without sacrificing intellectual substance.

One of the most important aspects of science blogs is that they introduce audiences to real people doing real science. Firstly, the public gains direct access to the scientific process, which instills appreciation in the reliability of scientific conclusions. Additionally, communicating with working scientists and seeing the work they do demythologizes the process of making knowledge. Science is shown as a tangible process that anybody can become involved with or contribute to. Putting a human face on the scientific process is a powerful tool for engaging the public, and one that some museums have already started using. For instance, as part of the “The Scientist is In” program at the National Museum of Natural History, staff curators set up shop in the exhibit halls, where they answer visitor questions and discuss their current research. This program has proved popular both among visitors and the scientists, who appreciate the opportunity to find out what their audiences are interested in. The implication from “The Scientist is In” and from science blogs is that the idea that scientists are universally poor communicators is false. Public education need not be the exclusive domain of education specialists, and many scientists are eager and willing to take part. Indeed, it is good practice to limit the number of layers of interpretation, as this often contributes to distortion of facts.

Another strong practice of science blogs is encouraging interaction from readers. Blog audiences enter gainful conversations with bloggers, and both parties benefit from this process. Museums can mimic this by inviting visitors to form and share their own conclusions. Process-focused science exhibits can show visitors what kinds of information scientists use to make interpretations, and then invite visitors to try it for themselves. For instance, an exhibit could use a variety of animal skeletons to demonstrate how scientists use indicators like gait and posture to determine how extinct animals may have behaved. The goal is to make the museum exhibit an interactive and intellectually involving experience. Involvement nurtures passion for content, which encourages repeat visits and deeper engagement. This is a new concept for museums, which have traditionally positioned themselves as institutions of intellectual authority. Unfortunately, there is little data on how to successfully integrate web-style discourse into a physical exhibit, because very few museums have tried it. Museums will have to be proactive in order to encourage substantive interaction with the exhibit content, or even among visitors. Some museums have successfully integrated user-generated content into exhibit spaces. For example, the “Playing with Science” exhibit at the London Science Museum invited visitors to place photographs of their own objects into the exhibit, alongside brief statements of the objects’ importance. However, something as simple as a comment board can also encourage visitors to respond intelligently to exhibit content.

Finally, museums should refocus content interpretation away from objects for their own sake and toward ideas. As stated previously, the public’s understanding of science is hindered by the media’s focus on encapsulated facts and discoveries, rather than broad, unifying concepts. Most scientific concepts are inherently logical and do not require specialized knowledge to understand if communicated properly. Evolution via natural selection is a good example. The concept that genetic variations within a population of organisms succeed or fail based on suitability to the present environment is easy to grasp, but a troublingly small percentage of the population is familiar with it. Even among visitors to natural history museums, who are more likely to accept evolution as true than the general population, less than a third are familiar with how natural selection works. Evolution is most important concept in biology and unifies the field. Therefore, it would not be difficult to integrate evolutionary concepts into virtually any exhibit on natural sciences. Communication of scientific concepts like evolution is more important for building science literacy than sharing scattered facts and impressive objects. Objects are excellent teaching tools, but are better when used as examples of underlying ideas.

Science communication in the media is at a tipping point. As the media has edged away from education and toward lowest-common-denominator entertaining, the public need for distinguishing reliable and unreliable information has increased. The misleading and inaccurate presentation of science in the media is woefully unhelpful for supporting an active and informed citizenry. Museums, with their high visibility and public trust, are well positioned to take steps toward reversing this trend. However, museum workers must first strike a balance between the sometimes conflicting goals of public appeal and accuracy. Science blogs are an excellent model for reliable, involving and applicable science communication, but they operate on a much smaller scale than museums. The challenge for museums, and any other media forms up to the challenge, will be to translate the strategies employed by blogs at the micro scale to large institutions.

Selected References

Diamond, Judy, and Margaret Evans. “Museums Teach Evolution.” Evolution. 61.6 (2007): 1500-1506.

Gregory, Jane, and Steve Miller. Science in Public: Communication, Culture and Credibility. New York: Plenum Press, 1998.

MacFadden, Bruce J., Betty A. Dunckel, Shari Ellis, Lynn D. Dierking, Linda Abraham-Silver, Jim Kisiel and Judy Koke. “Natural History Museum Visitors’ Understanding of Evolution.” Bioscience. 57.10 (2007): 875-882.

McLean, Kathleen. “Museum Exhibitions and the Dynamics of Dialogue.” Reinventing the Museum: Historical and Contemporary Perspectives on the Paradigm Shift. Ed. Gail Anderson. Lanham: Altamira, 2004. 193-211.

Simon, Nina. “Discourse in the Blogosphere: What Museums Can Learn from Web 2.0.” Museums and Social Issues. 2.2 (2007): 257-274.

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