Monday, December 20, 2010

Chickadee 65290 and This Blog -- A Matter of Endurance

This blog turned two years old today, a venerable age in the blogosphere and a vulnerable one as well.  Prompted by this birthday, a symbol of endurance came to mind – a chickadee banded in 1937 by conservationist and writer Aldo Leopold (1887–1948) with band numbered 65290.  I was surprised that this unbidden symbol wasn’t from the world of paleontology, but, so it goes.

In A Sand County Almanac and Sketches Here and There (1949), Leopold described how each year he and his family, over the course of the winter, banded birds they trapped on their farm.  The records of banded birds that ventured back into the traps over the years provided life histories of the winged inhabitants of this land.  As he wrote,
. . . to the old-timer the banding of new birds becomes merely pleasant routine; the real thrill lies in the recapture of some bird banded long ago, some bird whose age, adventures, and previous condition of appetite are perhaps better known to you than to the bird himself.

Chickadee 65290 and six other chickadees tagged in 1937 comprised the band of brothers and sisters of the “class of 1937.”

Here is a black-capped chickadee, captured in a photo taken by Danielle Langlois.  I assume that this is the species of chickadee banded by Leopold.  The Cornell Lab of Ornithology notes that this bird is “almost universally considered ‘cute’.”  Too true.

Over the next several years 65290 proved himself to be a survivor.  Leopold characterized 65290’s ability to endure as his “extraordinary capacity for living,” somehow greater in this bird than that of his brothers and sisters who fell to the wayside.  The attrition rate of the seven members of the class of 1937 was high.  Over half disappeared by the next winter, leaving but three.  Another was lost by the third winter.  65290 appeared the fifth winter, the sole representative of the chickadees born in 1937, and never reappeared again.

The hold on life of 65290 became even more startling when Leopold considered that, of the total number of chickadees banded during the entire decade (97), apparently only this single bird experienced a fifth winter.  The stark reality of the life of a chickadee is embodied in these statistics – 69% vanished sometime before their second winter and another 20% were lost before their third.

He pondered why life is so nasty, brutish, and short for the chickadee, a bird whose size means it has few enemies.

That whimsical fellow called Evolution, . . . , tried shrinking the chickadee until he was just too big to be snapped up by flycatchers as an insect, and just too little to be pursued by hawks and owls as meat.
The villain in the piece?  The weather, at times delivering lethal punches of shifting winds, rain, and sudden drops in temperature, is “the only killer so devoid of both humor and dimension as to kill a chickadee.”  Leopold acknowledged that, over time, wise choices may have graced the life of this particular bird, particularly that of finding dry shelter from the storm, shelter that shielded a tiny body from all sides, keeping any abrupt shift in wind direction from spelling death during the night.

In closing, Leopold offered a kind of prayer:

65290 has long since gone to his reward.  I hope that in his new woods, great oaks full of ants’ eggs keep falling all day long, with never a wind to ruffle his composure or take the edge off his appetite.  And I hope that he still wears my band.

Credit for Photograph
The photograph above of a chickadee is reproduced under the terms of the GNU Free Documentation License.  It is available on the web at this link.

Tuesday, December 14, 2010

Observing the Details of Nature ~ Naturalist Jean Henri Fabre

That inimitable observer, M. Fabre, . . . .
~ Charles Darwin, The Descent of Man

The ability to observe, to pay attention to detail – yes, a desirable attribute, particularly for someone interested in natural history.

A recent incident just served to confirm that it’s not really one of mine.  Guided by my skillful proofreading hand, an article in my fossil club’s newsletter offered up three different ways of spelling the name of a river in Mississippi.  Cold comfort that one variant was actually correct.  To cap it off, one of the misspellings was in the article’s title.  Human trumped technology since I ran a spell checker and evidently accepted each of those spellings.

Then there’s the great naturalist Jean Henri Fabre (1823 – 1915), whose close, careful observations of insect life in nature came to define him.  My recent, very belated discovery of Fabre prompts this post, and, nicely, it’s within striking range of his birthday on the 22nd of December.

Employed as a teacher until late middle age, Fabre was a keen cataloger of the minute details of the natural world around him.  For nearly the last four decades of his life, he supported himself with many articles and books, and the natural world he examined was largely defined by the limits of a small walled-in plot of land in Serignan in Provence, France.  Primarily, he studied insects – their anatomy and their behavior – and did it with such skill that, even as a young man, he impressed that consummate observer Charles Darwin.

Darwin cited him in On The Origin of Species when Fabre was only in his late 30s.  In Darwin’s discussion of how natural selection might modify animals’ instincts by taking advantage of an occasional, opportunistic action, he notes that:

. . . M. Fabre has lately shown good reason for believing that although the Tachytes nigra [a predatory solitary wasp] generally makes its own burrow and stores it with paralysed prey for its own larvae to feed on, yet that when this insect finds a burrow already made and stored by another sphex [a digger wasp], it takes advantage of the prize, and becomes for the occasion parasitic.  In this case, as with the supposed case of the cuckoo, I can see no difficulty in natural selection making an occasional habit permanent, if of advantage to the species, and if the insect whose next and stored food are those feloniously appropriated, be not thus exterminated.  (1859 edition)
Though the two communicated warmly on occasion late in Darwin’s life, Fabre remained a critic of the theory of evolution by natural selection.  In a letter to Fabre dated January 31, 1880, Darwin is quintessentially Darwin, friendly, deferential, and assertive.  He begins by praising a recent volume of Fabre’s Souvenirs entomologiques (which ultimately grew to a 10-volume series of books published over some 30 years).  Darwin writes, “Never have the wonderful habits of insects been more vividly described, and it is almost as good to read about them as to see them.”  He then goes on the offensive, first, gently asking Fabre to correct an incident involving Darwin’s grandfather Erasmus Darwin that was recounted in the book; he generously presumes it was due to a faulty translation Fabre read about the incident.  More pointedly, he takes Fabre to task for his dismissal of the theory.  Darwin delivers a somewhat stinging rebuke within the cloak of a compliment – pure Darwin:
I am sorry that you are so strongly opposed to the Descent theory; I have found the searching for the history of each structure or instinct an excellent aid to observation; and wonderful observer as you are, it would suggest new points to you.  (The Life and Letters of Charles Darwin, 1887)
Fabre had ended his book with a lament about the death of his young son.  Darwin, who knew first hand the pain of the loss of a child, responds with heartfelt emotion:   “Permit me to add, that when I read the last sentence in your book, I sympathised deeply with you.”  But, science will out, and he immediately adds a postscript in which he comments approvingly on Fabre’s account of insects finding their way home, and suggests an experiment for Fabre to try.

Fabre wedded his powers of observation to a writing style of passion, poetry, and immediacy.  It is interesting to contrast his prose with Darwin’s.  The latter’s is eminently serviceable and readable, but the syntax can be complex and the prose seldom rises to the heights Fabre seemed to achieve effortlessly.  Their differing motives for writing had much to do with it.  Darwin built scientific arguments, proposed profound theories and defended same.  Fabre wrote to chronicle his observations and, perhaps even more relevant, to put bread on the table; by necessity, he was seeking a broader, popular audience.

The power of Fabre’s writing was not lost on the naturalist and writer Gerald Durrell who, at age 10 in the mid 1930s, was introduced to Fabre’s books by his older brother Lawrence, the novelist.  Gerald Durrell wrote that Fabre “opened up a magical world” in which, not only was strange insect behavior described and explained, but all of nature was at play, “from mushrooms to fossils and his writing meant that you were suddenly transported out into the open air instead of, as with so many Victorian naturalists, into a museum.”  (The Amateur Naturalist:  A Practical Guide, 1984)

Of Fabre’s written work that I’ve sampled, some essays absolutely enthrall me, and other pieces, despite the lyricism of the writing, leave me a bit cold, particularly when the naturalist delights in describing some of the more egregious behaviors of insects.  In the latter category, here’s Fabre on the Ammophila, a wasp, whose larvae are parasitic on caterpillars and sawflies:
Let us recall the table-manners of a larva living on prey, the Ammophila’s for instance, when devouring its Caterpillar.  A hole is made in the victim’s side; and the head and neck of the nursling dive deep into the wound, to root luxuriously among the entrails.  (The Life of the Fly, 1913)
Writing is lovely, topic not so much.  Easy to understand the attraction of a passage like this to a 10-year old.

Then there’s the Fabre who delights me, and it is telling, I suppose, that much of what I really like is often not the careful, detailed observations of insects and their behavior, but the personal asides and his expansive prose sojourns through natural history.  For example, in The Life of the Weevil (a 1922 compilation of the essays on weevils that appeared in the 10 volumes of the Souvenirs entomologiques), Fabre describes how, in the wintertime in Provence when “the insect takes an enforced rest,” he gains some amusement from numismatics, studying the Roman, Greek, and other ancient coins that local farmers find when they till the soil.  A coin strikes his fancy and, in flowing prose, he describes the details of the portrait on it:
On the obverse, a head of Diana of Ephesus, chub-faced, full-cheeked, thick-lipped.  A receding forehead, surmounted by a diadem; an abundant head of hair, streaming down the neck in a cascade of curls; heavy eardrops, a pearl necklace, a bow slung over the shoulder.
Still he finds this study of coins pales in comparison to “another science of numismatics, far superior and less costly, which, with its medals, the fossils, tells us the history of life.  I refer to the numismatics of stones.”  The very stone house in which he lives is the repository of this history of life, inspiring Fabre to language that approaches poetry:
My very window-sill, the confidant of bygone ages, talks to me of a vanished world.  It is, literally speaking, an ossuary, whose every particle retains the imprint of past lives.  That block of stone has lived.  Prickly spines of Sea-urchins, teeth and vertebrae of fish, broken pieces of shells and fragments of madrepores [a kind of coral] form a conglomeration of dead existences.  Examined stone by stone, my house would resolve itself into a reliquary, a rag-fair of ancient things that were once alive.
That block of stone has lived.  A perfect line.

Fabre describes the quarries from which the stone used in the building was dug and expounds on the myriad fossils that come forth from the rock.  He captures perfectly how teeth, particularly shark teeth, stand out from other fossils because they are “still wonderfully polished in the midst of their rough matrix and as bright with enamel as in the fresh state.”  These teeth and the other fossils tell him of a very different ancient landscape, or, more properly, shallow seascape.  How they appear in the matrix suggests to him the nature of waters that were once here, the proximity of land, and how these many creatures died.  Though he may not have embraced Darwin’s theory, Fabre recognized that entire species had been “mown down” by “that patient renewer of the harmony of things.”

Within the sheets that flake from a local stone, he finds perfectly preserved fossil fish.  These stone pages contain marine and terrestrial fossils, including his favorite organisms, insects.  And when he finds tiny gnats, he memorializes them in the contradiction between their life and their death:
What shall we say of these frail Midges enshrined intact in their marly reliquary?  The feeble creature, which our fingers could not pick up without crushing it, remains undisturbed beneath the weight of the mountains!

Source of Pictures
Each picture of Fabre comes from Commons.wikimedia.  Reportedly the copyrights on these images have expired.  The first picture can be found here and the second here.

Thursday, December 2, 2010

A Romantic's View of Expert Systems

Who will identify all the fossils that are just now starting to weather from the rocks?
~ Roger L. Kaesler

I am a romantic about many aspects of paleontology, including the sages that grace the science.  I suspect it helps that I am also an amateur at all of this and have never been behind the scenes.  My fleeting encounters with professional paleontologists have left me with the impression that each has a profound grasp of his or her domain, an ability to see the micro and the macro at once.  They define the term expert.  Yes, it’s a romantic view.

I rarely have the opportunity to turn to one of those paleontological sages when I’m faced with the challenge of identifying precisely what genus or species of shark gave up the fossil tooth that lies before me.  My next best approach involves identification guides, articles, a few key websites, and the like.

One resource that I’ve always thought held promise was sort of an “expert in a box” or, more accurately, an expert in a “knowledge base” (to use a term from computer-based expert systems, something else for which I also have amateur status or less).  A knowledge base for fossil identification could take one of several forms and need not be delivered through technology.  It might be a series of “rules” (e.g., IF/THEN statements) with an initial rule that draws some basic distinction within the ranks of the type of fossil specimen being studied.

An example of such a set of rules was prepared several years ago by Robert Purdy of the Smithsonian Institution.  A Key to the Common Genera of Neogene Shark Teeth (revised March 2006) is a set of 50 rules, each of which has 2 possible responses.  The response to a rule dictates which rule the user moves to next or whether a possible identification of the shark genus is ready to be offered.  Purdy’s Rule 1 requires the user to decide whether the fossil tooth has (a) one cusp or (b) several cusps.  That clearly is a fundamental difference that separates fossil shark teeth.  In Purdy’s key, if the tooth has a single cusp, then the user moves on to Rule 2; if multiple cusps, Rule 25 is the destination.  Though there are 50 such rules, some identifications come quickly, after invoking only a few rules.  The genus of the cow shark tooth, pictured below (image on left is of the lingual side, image of right is of the labial) can be identified as Notorynchus in three steps – Rules 1, 25, and 26.

I have to admit that when I applied the key to the pictured tooth I made a judgment call on the last rule choosing between the (a) and (b) options of Rule 26.  Rule 26(a) applies to a tooth with 3 to 4 cusplets while Rule 26(b) cites 7 to 10 cusplets.  This tooth appears not to fall into either category, having instead about five cusplets.  I decided to go with the option that came closest to the specimen, Rule 26(a), which immediately generated the Notorynchus identification.  Of course, with this particular tooth, I’d already consulted my other resources, though not a living expert, and “knew” where the process should be heading – Notorynchus.

I have spent some time working on a knowledge base (in Excel) to help in the identification at the species level of fossil teeth from Carcharhinus sharks, the so-called gray or requiem sharks.  Bretton Kent in his seminal Fossil Sharks of the Chesapeake Bay Region (1994) captures the essence of why, absent a human expert at my beck and call, I’ve invested time in trying to build this knowledge base.  “The identification of individual Carcharhinus species based solely on teeth can be difficult given the degree of convergence in tooth form among different lineages.”  (p. 80)

It also shouldn’t be surprising that distinguishing among species through a set of rules may be even more problematic than using rules to distinguish among genera as in Purdy’s key.  Differences among fossil specimens from diverse species are frequently very subtle.  For instance, serrations can either present or absent.  Pretty obvious, except sometimes serrations are tiny, requiring a hand lens to see.  When do serrations shift from being no longer tiny and difficult to see, but regular?  When are they no longer regular but coarse?  At the extremes the differences are obvious, but, there is, to use Kent’s word, convergence that requires distinguishing among shades of gray.

So, in my limited experience, the application of a knowledge base isn’t always, or even usually, akin to following a single, obvious thread directly from specimen to a conclusion about identity.  Rather, there are knots to contend with and these stem largely from the fact that we’re dealing with what were once living organisms which are inherently variable, with a fossilizing process that introduces variability, and with rules that are more or less useful depending upon how carefully they’ve been worded.  Ultimately, one needs to use some informed judgment.  A knowledge base can be useful in the identification of a specimen, but, from my perspective, not sufficient.

Several decades ago, expert systems emerged from work in computer-based artificial intelligence.  An expert system was defined as “a computer program designed to model the problem-solving ability of a human expert.”  (John Durkin, Application of Expert Systems in the Sciences, Ohio Journal of Science, vol. 90, no. 5, 1990, p.171.)  Among the components of such a system that Durkin identified were (1) a knowledge base and (2) something called an “inference engine” which integrated the data input by the user with the information residing in the knowledge base to craft a solution to the problem under analysis.  Apparently, the inference engine would be programmed to deal with the uncertainty introduced by incomplete information, yielding probabilities for different solutions.  Fossil identification was one problem that some programmed expert systems to address.

I recently stumbled across the presidential address to The Paleontological Society delivered by paleontologist and geologist Roger L. Kaesler in 1992, nearly 20 years ago.  In it, Kaesler stated that paleontology faced a future with far too few paleontologists who were immersed and expert in the taxonomy, evolutionary history, and geography of major groups of fossils.  He warned that “an acute shortage of systematic paleontologists” threatened the science.  (A Window of Opportunity:  Peering into a New Century of Paleontology, Journal of Paleontology, vol. 67, no. 3, 1993.)  He saw a 15-year window of opportunity in which to prepare for this future, and suggested that one promising way to preserve the systematists’ knowledge and bring it to bear on future fossil finds was the building and application of expert systems.

The window of opportunity Kaesler identified closed in 2007 (sadly, that was also the year he died).  I wonder, has the dearth of systematic paleontologists has come to pass, an event that he apparently thought inevitable?  Is the science increasingly relying on an array of expert systems to identify and classify fossils, and to define their relationships among each other?

As for the first question, in a recent (2008) piece, Norman MacLeod, the Keeper of Paleontology at the Natural History Museum in London, writes, "This expertise deficiency, which has come to be called the 'taxonomic impediment', is with us now and will only become more serious as time goes by unless some means is found to address its effects."  (Introduction, Automated Taxon Identification in Systematics:  Theory, Approaches and Applications, edited by MacLeod, 2008, p. 3).  He is writing not just about a shortage of individuals with systematic knowledge affecting paleontology but more broadly, including biology and zoology.

As for the second, MacLeod posits that the dream of automated taxon identification in general, not just of paleontological remains but also of extant organisms, is still alive but clearly has yet to be realized.  He concedes that "most practicing taxonomists still believe such systems are the stuff of science fiction."

I’m too much of a romantic and a bit soured by my brief encounters with efforts to capture knowledge in a box to think we can ever replace that human expert, that systematic paleontologist who seemingly knows it all in his or her domain.

In Trilobite:  Eyewitness to Evolution (2000), Richard Fortey describes his early years at the University of Cambridge’s Sedgwick Museum of Earth Sciences, where he labored to extract trilobites from material he had collected at Spitsbergen, north of the Arctic Circle.  The renowned paleontologist Harry Whittington was mentoring him, his “guru.”  For Fortey, Whittington does what an irreplaceable human expert system does.  Fortey writes,

From time to time Harry Whittington would appear and make encouraging remarks, or put me right when I placed the wrong head and tail together. (p. 38)

Whittington died earlier this year (2010) at the age of 94.

Friday, November 26, 2010

The Very Real, Multidimensional Hadrosaurus foulkii ~ Convoluted History and Rejoinder to a Critic of Natural History Museums

At some point in the 1870s or possibly the very early 1880s, photographer James F. Jarvis set up his camera and array of equipment at the Smithsonian Castle and took photographs of the institution’s mounted skeleton of Hadrosaurus foulkii, a dinosaur from the Cretaceous period (about 146 to 66 million years ago).  From the glass negatives he prepared at the Smithsonian, Jarvis produced a stereoview or stereograph featuring the Hadrosaurus.  (Stereoviews or stereographs – cards whose dual mounted photographs generate a 3-D image when viewed through a stereoscope – have been considered previously on this blog.)

I recently added a copy of this stereoview to my collection.  The full face of this stereoview and a closeup of one of the two pictures are shown below.  The Hadrosaurus is prominent in the foreground, facing into the picture.  In front of it is a large Himmalayan tortoise shell from the Miocene epoch (about 23 to 5 million years ago), and in front of the tortoise is the restoration of an Irish elk, the Pleistocene epoch giant deer that went extinct some 11,000 years ago.

Jarvis was well known for the manufacture of stereoviews of Washington, D.C., and various series of stereoviews from government explorations of the western U.S..  For a period, he ranked among the country’s major producers of this popular photographic medium.

Originally, I thought it would be relatively easy to compose a posting on the subject of this specific stereoview.  Clearly, I had no clue about the richly convoluted the history of this mounted skeleton of Hadrosaurus.  Nor did I recognize that these photographs speak to a contemporary debate about the display of “fake” skeletons by natural history museums.  (Some of the sources I consulted are identified in the text; most are included in the discussion of sources at the end.)

Initially, though, I wanted to place a date on the stereoview, well, actually, the taking of the negative.  The Smithsonian has produced a fascinating webpage on stereoviews of the institution.  According to the information appearing there, beginning in 1874, the Hadrosaurus skeleton was on display in the Main Hall of the Smithsonian Building, a structure usually referred to as the Castle.  Then, in 1882, along with other skeletons and specimens, the Hadrosaurus was moved to the Smithsonian’s National Museum building.  This Jarvis stereoview shows the Castle’s Lower Main Hall looking east, which means it had to have been taken between 1874 and 1882.  Unfortunately, that doesn’t really narrow it down very much.

What was the source of the skeleton?  The fossilized bones of  a giant creature had been discovered in 1858 in Haddonfield, New Jersey, by Philadelphia lawyer and fossil hunter William Parker Foulke.  Foulke called in Joseph Leidy, a professor of anatomy at the University of Pennsylvania and curator at the Academy of Natural Sciences in Philadelphia, who identified them as coming from a dinosaur, a term that had been coined by English paleontologist and biologist Richard Owen in the early 1840s.  This was the most complete dinosaur skeleton that had ever been found anywhere.  Leidy named the dinosaur Hadrosaurus foulkii (the genus name means “bulky lizard” and the species name recognizes Foulke).

A decade later, the English anatomist, scientific illustrator, and sculptor Benjamin Waterhouse Hawkins came on the scene, having traveled to the U.S. to create a dinosaur display for a new museum in New York City.  After consulting Leidy about the New York display, he undertook the task of mounting the Hadrosaurus skeleton for the Academy of Natural Sciences.  With assistance from Leidy and one of Leidy’s students, Edward Drinker Cope, Hawkins created a mounted dinosaur skeleton using plaster casts of the bones at hand and plaster reconstructions, based on educated guesses, of those that were missing.  This was the first mounted dinosaur skeleton ever produced and, as we all know, this kind of display was destined to become a staple of natural history museums worldwide.

The skeleton went on display at the Academy in late 1868, attracting throngs of visitors, so many that officials of the Academy took steps to reduce the number of visitors, curtailing the days it was open to the public and charging admission.  The success of the display apparently was not lost on other institutions that then sought to obtain their own copies; Hawkins produced several.  According to Richard C. Ryder, the Smithsonian received a copy sometime between March 1874 and mid 1875.

After being displayed in the Smithsonian Castle, the Smithsonian’s Hadrosaurus was moved in 1882 to the National Museum building where it remained until perhaps 1893 or 1894.  Ryder says that it was then sent to the Field Museum of Natural History in Chicago, “only to be discarded when the museum moved to new quarters a decade later.”

Breathtakingly innovative for its time, Hawkins’ Hadrosaurus skeletons got some things right, and missed the boat on some others.  For instance, the posing of the Hadrosaurus in an upright, bipedal position reflected Leidy’s accurate understanding of the dinosaur.  But, the three-pronged supporting position of the hind legs and the tail, giving the creature a kangaroo-like appearance, was ultimately disproven by subsequent research.  The drawing below depicts current understanding of the positioning and use of the tail (the picture comes from the New Jersey Geological Survey).  The Academy’s clutch of Hadrosaurus bones lacked a skull, so Hawkins made one based on the head of an iguana lizard, a creative though erroneous solution to the problem.

One passing comment on Leidy’s student, Edward Drinker Cope.  Cope became one of the country’s foremost paleontologists and engaged in the famous no-holds-barred competition against Othniel Charles Marsh to find dinosaur fossils – the so-called Bone Wars.  This conflict had a Hadrosaurus connection.  Before the battle royal began, the two men spent what paleontologist Michael Novacek describes as “a friendly week together poking around Leidy’s old Haddonfield quarry for hadrosaur bones.”  Hoag Levins, in an article on his great website Finding the World’s First Dinosaur Skeleton:  Hadrosaurus foulkii, asserts that the Cope-Marsh conflict had its roots in this friendly time together.  Cope generously introduced Marsh to the managers of different pits from which dinosaur bones were being collected.  The falling out occurred when Cope learned that, shortly after they left the area, Marsh returned alone, money in hand, to bribe the managers to send him bones and word of what they had found.

Hawkins’ Hadrosaurus skeleton also has some bearing on a debate of sorts that involves natural history museums today.  Earlier this year, “Thomas H. Benton” (the pen name of William Pannapacker), a professor of English at Hope College, published a piece in The Chronicle of Higher Education entitled Getting Real at Natural-History Museums (July 1, 2010) in which he takes these museums to task for succumbing to the entertainment bug and for mounting displays that contain “fakes.”  Venturing into the Academy of Natural Sciences in Philadelphia with his daughter in search of the real dinosaur skeletons he remembered from his youth, he was dismayed to discover only replicas.  He asserts

Natural-history museums like the [Academy of Natural Sciences] emerged to provide exhibits that were reliably authentic and that could instruct the public and build the credibility of science in a period, like our own, in which pseudoscience had a strong hold on the general imagination.  Of course, the replicas in natural-history museums, unlike [P.T.] Barnum’s humbugs, present authentic science, but, over the last few generation, museums have become more willing to use substitutes in place of real artifacts.  It seemed like a good idea at the time. . . .

You could say that a fake skeleton educates as well as a real one, and it surely looks as good for publicity purposes.  But one of the fundamental attractions of natural-history museums – and museums in general – is the aura of authenticity and the power they have to inspire the imagination, particularly for children, in an era that is increasingly characterized by the virtual and the simulated.  That was not true when fossil replicas were first introduced – the changes were made with the best of intentions – but it is surely the case now.

Frankly, I am always suspicious of people who argue that there was once a “golden age” and that we’ve lost our way.  Too often that “golden age” proves to have been a mirage, the reality being nothing like what was remembered.  Clearly, that's the case in this instance.

A wonderful response to “Benton” was penned by Chris, a museum curator, on his blog Prerogative of Harlots (July 26, 2010).  He observes, “When Benton refers to fakes, he’s actually taking about casts – specifically the cast dinosaur skeletons that many museums exhibit in their galleries.”  Why do they do that?  For one thing, there are very few complete fossil skeletons.  Most are exceedingly incomplete.  So even a skeleton of an individual specimen that includes real bones will include many replicas of bone.  Chris points out that the dinosaur “Benton” remembers from his youth at the Academy was a composite, not the “real” thing.  Chris describes the precision behind the creation of casts, a process producing something that is

as close to the fossil as it’s possible to get without actually owning it.  Casts are heavily used in paleontology because of the scarcity of fossil specimens – they are exchanged between museums and sent out on loan to researchers.  We assign them catalog numbers and treat them in the same way as we would treat any museum specimen.

He argues, persuasively in my mind, that the answer to the question “Is it real?” when standing before a dinosaur skeleton cast is

Absolutely, in the sense that there was once an animal that looked like this, we have the bones to prove it, and this exhibit specimen could not have been made without those bones.

Hawkins’ Hadrosaurus foulkii itself constitutes another strong response to “Benton.”  From the very outset of museums displaying mounted dinosaur skeletons, they were real only in the sense that Chris described, not in the way “Benton” misremembered from his childhood and before.  Then and now, they draw crowds and inspire the imagination, regardless of whether this or that bone is rock or a cast.

One final small note, Hawkins is tied to the Hadrosaurus stereoview in another way; it’s his restoration of an Irish elk appearing in the background.


The Academy of Natural Science has some useful information on its website for the exhibit about Hadrosaurus foulkii that it mounted in 2009.

Richard C. Ryder wrote a very interesting piece on dinosaurs in stereoviews entitled Dinosaurs Through the Stereoscope, Stereoworld, March/April 1985.

For a great exploration of Hawkins’ work, including the process for creating the mounted Hadrosaurus skeleton, see The Art of Bones:  Nineteenth-century Artist Benjamin Waterhouse Hawkins Still Influences How Prehistoric Life is Represented Today, by Robert McCracken Peck, Natural History, December 2008 – January 2009.  This article was adapted from the book All in the Bones: A Biography of Benjamin Waterhouse Hawkins, by Valerie Bramwell and Robert M. Peck.

Among good sources of background on Hadrosaurus is When Dinosaurs Roamed New Jersey by William B. Gallagher, 1997.

The Cope-Marsh competition is described in many sources.  Time Traveler:  In Search of Dinosaurs and Ancient Mammals From Montana to Mongolia  by Michael Novacek (2002) includes a brief, concise overview of the Bone Wars.

Monday, November 15, 2010

Standing at an Intersection

[Our imagination] will grow weary of conceiving things before nature tires of producing them.
                                        ~ Blaise Pascal, Pensées (1670)

Intersections are places of possibility and often of contradiction.  Last week, at the Smithsonian’s National Museum of Natural History, I stood at an intersection of science and art.  No, much more than that, a conjoining of mathematics, nature, handicraft, community, and perhaps a touch of evolution.  I visited an exhibit featuring both the Smithsonian Community Reef which was made by local handicrafters, and the Hyperbolic Crochet Coral Reef, of which the community reef is a part.  This combined project brings together hyperbolic geometry and the handicraft of crochet in a worldwide movement involving many artists in many places for the crocheting of “woolly” coral reefs.

From a distance – an unusual, huge mound of multicolored yarn.

Up close – a breathtaking work of art, and a nexus of contradictions.  The structure is the recreation in yarn and myriad other materials of a coral reef, modeled both on reefs that exist today . . . and reefs, through flights of crochet fancy, never seen before.

Here in the Smithsonian Community Reef are easily recognizable corals, such as brain, branching, or gorgonian fan coral.  Most denizens of this reef are sessile (fixed and stationary), but not all.  Floating amid the coral is a striking jellyfish with delicate purple tentacles.

In nature, a coral reef reveals manifold contradictions.  Many types of coral thrive in clear tropical water, places that are poor in nutrients.  Yet, they create structures that teem with life.  They eat other organisms, stinging and subduing prey.  Yet, for most reef building coral, vital life processes depend upon a complex symbiotic relationship with photosynthetic algae (zooxanthellae), a relationship speaking to eons of evolutionary change.  The most prosaic and visual level of this relationship means that, without the algae, the coral are white, bleached of color.  (The National Oceanic and Atmospheric Administration website provides a clear and succinct introduction to coral reefs.)

At the mathematical heart of the crochet coral reef are many hyperbolic planes crocheted from yarn, wire, and plastic.  Hyperbolic geometry, by its very contradiction of Euclidian geometry, brings us closer to an array of distinctive shapes and forms produced by nature through evolution.  As mathematician and journalist Margaret Wertheim has described in it,

[T]he natural world teems with swooping, curling, crenellated forms, from the fluted surfaces of lettuces and fungi to the frilled skirts of nudibranchs and sea slugs and anemones.  Nature just loves hyperbolic structures.                    (Article by Mick Mycoff entitled Margaret Wertheim:  Complexity, Evolution and Hyperbolic Space, appearing in the journal Evolution:  Education and Outreach in 2008, p. 531.)
Margaret Wertheim and her twin sister Christine are director and co-director of the Institute For Figuring and the moving spirits behind the Hyperbolic Crochet Coral Reef.

Let me make no pretense of actually understanding hyperbolic geometry.  I have grasped enough to recognize that it arises from a contradiction of Euclid’s fifth postulate, the parallel postulate, which most of us know through John Playfair’s axiom.  That axiom states:

Through a given point not on a given line there passes at most one line that is parallel to the given line.  (Michael Serra, Discovering Geometry:  An Inductive Approach, 1997, p. 730)

In contrast, in hyperbolic space, there are many, indeed, an infinite number of lines through a point not on a given line that are parallel to that line.  See figure below.  Margaret Wertheim notes that it is called hyperbolic because of “this abundance of parallels.”

The lines in this two dimensional Euclidian figure appear, with one exception, curved.  Margaret Wertheim asserts, “From the point of view of someone inside the hyperbolic surface, all these lines would be perfectly straight and none would meet the original line.”  (Margaret Wertheim:  Complexity, Evolution and Hyperbolic Space.)

I envision hyperbolic space as curved, fluted, twisted.  I am helped immeasurably by mathematician Daina Taimina, who in 1997, after watching her mathematician husband David Henderson nurture fragile and hard-to-make paper models of hyperbolic space, crocheted a model out of yarn.  Here’s one crocheted by my mathematician wife following Taimina’s directions in Crocheting the Hyperbolic Plane, an article Taimina and David Henderson wrote for The Mathematical Intelligencer (vol. 23, no. 2, 2001).

There is no overestimating the importance of having a model at hand, one that can be scrutinized and played with.  Reportedly, one math professor, no stranger to teaching hyperbolic geometry, commented upon seeing one of Taimina’s model, “Oh, so that’s how they look.”  (Michelle York, Professor Lets Her Fingers Do the Talking, The New York Times, July 11, 2005.)  Using a crocheted model of hyperbolic space, one can show that those apparently curved lines are straight, as Margaret Wertheim demonstrates in a video of an entertaining talk she delivered at one of the TED (Technology, Entertainment, Design) conferences in 2009.

Nature creates hyperbolic structures for a good reason; hyperbolic structures greatly increase the surface area exposed per amount of volume, a boon to sessile filter feeding animals and plants.  The process of crocheting hyperbolic figures, according to the Wertheims, mimics evolution.  Crocheters have deviated from the “mathematical perfection” that Taimina used in creating her models of hyperbolic space, constantly tweaking the underlying patterns and discovering, in the process, that small changes in the algorithm may have large consequences for the final form.  New shapes emerge, some find favor and end up being selected to inhabit the Hyperbolic Crochet Coral Reef or one of the satellite communities.  On the Hyperbolic Crochet Coral Reef website, the Wertheims invoke the word “species” in their discussion of the evolution of new shapes.  Yes, in the first instance, they place the word in quotation marks, but, as they go on, they become more exuberant in drawing connections to evolution.

Just as the teeming variety of living species on earth result from different versions of the DNA-based genetic code, so too a huge range of crochet hyperbolic species have been brought into being through minor modifications to the underlying code.  As time progresses the models have “evolved” from the simple purity of Dr. Taimina’s mathematically precise algorithms to more complex aberrations that invoke ever more naturalistic forms. 
They conclude, “The Crochet Reef thus serves to engage audiences on the subject of evolution and to demonstrate playfully how evolution works.”

I agree that the shapes and creatures are evolving, but at some remove from what is meant in nature by evolution.  It is intellectually stimulating to cast the process of creating crochet coral in terms that speak of evolution, but, to my mind, it is at some cost to the substance of the concept and process in nature.  Still, that is a minor quibble in the face of the amazing Hyperbolic Crochet Coral Reef.

As I stood at that intersection in the National Museum of Natural History last week, I was reminded of the late Benoit Mandelbrot, who saw yet another kind of geometry in aspects of nature (and in so doing, robbed me of sleep many years ago as I wrote and tweaked computer programs to generate the strange Mandelbrot set).  He observed

I claim that many patterns of Nature are so irregular and fragmented, that, compared with Euclid – a term used in this work to denote all standard geometry – Nature exhibits not simply a higher degree but an altogether different level of complexity.
                  ~ Benoit B. Mandelbrot, The Fractal Geometry of Nature (1983)

Sunday, November 7, 2010

State Geological Surveys ~ Rare Moments of Civilized Joy in the Quest for Online and Free

 I am struck first by the abstract beauty of a geologic map, but, as Martin Schmidt writes,

The nice part is that the attractive patterns also mean something and give us some information, as long as we can read the message in the pattern.  (Maryland’s Geology, 1993, p. 23)

Geologic maps hold keys to the fossil pursuit.  Without them, the fossil hunter searches blind or only follows in someone else’s footsteps.  With them, there’s more guided purpose to the effort, though, certainly, no guarantee of success.  I’ve written about these maps several times during the life of this blog, including a description of New Zealander Joan Wiffen’s fixation on the legend of a geologic map which asserted that reptile bones could be found in certain of that country’s Cretaceous formations.  With that encouragement, she labored and brought forth dinosaur bones where many had concluded there were none.

A geologic map identifies and locates an area’s rock formations – either where the formation is exposed or where it lies beneath unconsolidated material on its surface.  Such a map labels these bedrock formations with letter codes keyed to its legend, and sometimes illuminates them with color, as with the portion of a geologic map of Arkansas at the head of this posting.  The legend of a geologic map describes the rocks and, as with Wiffen’s bit of serendipity, may on occasion characterize the formation with a phrase that sets a heart racing, a phrase like “richly fossiliferous.”

Recently, while doing some research for this blog, I was reminded how pursuit of a geologic map mirrors that for fossils – it requires study, patience, hard work, and luck.  Not for the faint of heart, particularly if one wants a map online and free.  Given that I’m more than happy to consult 30 or 40 year old maps, I don’t think that’s asking too much – online and free.

The previous posting on this blog included some discussion of the Battle of Wilson’s Creek which occurred in Missouri during the Civil War.  To bolster a fossil connection for that battle, I searched for a geologic map covering the battlefield.  The Missouri state geological survey seemed like a good bet; I followed a link from the Association of American State Geologists to the Missouri Department of Natural Resources.  The webpage that opened up looked very promising with a beckoning link labeled “Geologic Maps” on the right side of the page.

A click on “Geologic Maps” took me to a page featuring that dreaded word – “purchase” – the first of the stumbling blocks that the Missouri state geological survey put in my way.  I often come up against that commercial hurdle digging through state geological survey websites, but seldom so quickly.  Might I have missed the mother lode of free digital maps on the website?  Sure, but I doubt it.  I have to conclude that Missouri gives nothing in the line of geologic maps away for free.  The state certainly showed me.

Game, set, match?  Failure?  Not yet.  My next step was to turn to the U.S. Geological Survey and, because Missouri has received matching grants from the USGS’s STATEMAP program to support mapping under a state-designed geological framework, it kindly provided a link to that program on the USGS website.  Given my experience so far, I was not surprised to find that the online products listing for Missouri on STATEMAP showed zilch under “New Mapping.”  As with any fossil hunt, it’s the glint on the periphery that marks possibility.  A link at the side of the STATEMAP products page labeled “Geologic Map Database” led me to the Geoscience Map Catalog of the National Cooperative Geologic Mapping Program (NCGMP).

Lo and behold, a place name search for Wilsons Creek, Missouri (hey, why not swing for the fences?), offered up several related links, including one to Wilson's Creek National Battlefield.  That link took me to a page where the user can specify the kind of map desired – in this case I told the system I wanted a map of bedrock and I wanted it in a digital format.  (Still swinging for the fences.)

Of the several maps offered up from this search, one –a map published in 1987 – was a winner.  It’s ironic that this one was prepared by staff of the Missouri geological survey.  Anyway, zoom in on the map, search a bit, and, then, experience a moment of civilized joy.  There on my computer screen is the battlefield and its geological formations in glorious . . . well, not so glorious grayscale.  No color – a small price to pay for the pleasure of a successful quest.  (Elsewhere on the map was the key explaining the coding for the bedrock formations labeled Muo and Mlo which are the primary ones at the battlefield.)

I’ve endured similarly frustrating experiences with the several other state geological surveys’ websites I’ve searched, but seldom has the “purchase” word shown up as quickly and as definitively.  I can usually find a spot where a particular state survey has posted a digitized out-of-date set of geologic maps.  The experience can be rewarding with some surveys.  The geological map at the head of this posting surfaced with some rooting around on the Arkansas survey’s website and was produced in 1976 (and revised in 1993) by the USGS and the Arkansas Geological Commission staff.  Still, as my Missouri experience illustrates, it’s good to know about the USGS mega collection of geologic maps.

Perhaps, restricting my quest to the USGS is the solution nearly every time.  But, should it be?  Why does someone like me, a casual, paleontologically oriented user have trouble with state geological surveys online?  Aren’t they in the business of producing and disseminating geologic maps?

The answers to these questions lie in the nature of the surveys, their tangled histories, their missions and purposes.  Significantly, a state geological survey is not a specific survey, but, rather, an entity or agency whose responsibilities do include mapping of the state’s geology but often extend well beyond that.  Each of the state surveys has a different history and a differently nuanced set of missions.  Further, as a search of just one or two of their websites will reveal, each has a unique approach to making its products available.  Compounding all of this, each makes use of the web with different degrees of grace.

The oldest state geological surveys are approaching 190 years of age.  North Carolina’s survey, legislatively authorized in 1823, is the oldest, while Massachusetts (1830) has been labeled the “first full-blown state supported geological survey.”  (Walter B. Hendrickson, Nineteenth-Century State Geological Surveys:  Early Government Support of Science, Isis, Vol. 52, No. 3, Sep. 1961, p. 359)  (I’m uncertain about why Massachusetts merits this designation, perhaps it has to do with the breadth of the authority and provision of ongoing state funding.)  The State Geological Surveys:  A History offers an interesting glimpse of the often difficult conception and birth of each state survey (edited by Arthur A. Socolow, 1988, and available on the website of the Association of American State Geologists).

Commercial and agricultural interest sparked the creation of these surveys, particularly the desire to support internal improvements related to transportation, such as the placement and building of canals and roads.  Hendrickson observes that, though a desire to advance science and general knowledge was present at their founding, the foremost objective, the trumping objective, was the generation of “economically useful information.”

So, folks like me with avocational interests are not state geological surveys’ primary kind of audience.

This utilitarian interest on the part of state legislatures played out in the surveys in wonderfully narrow-minded ways.  For example, in the late 19th Century, Arkansas was once again supporting a state geological survey, after an on-again off-again dalliance with the idea.  Support for the survey this time arose from an interest in assessing gold and silver deposits in the western part of the state.  When the survey reported that the gold prospects for the mines that were then open were nil, annoyed legislators curtailed state funding and the survey went away, not to return as a discrete entity until 1923.  Shoot the messenger, the tried and true response of legislators at every level.

The creation of the USGS in 1879 played a role in strengthening this focus of the state surveys because the USGS, as Hendrickson puts it, took over the “theoretical work,” which “left the state survey free to undertake practical work.”  (p. 371)

I’ll take one last stab at it.  Even if I’m not a member of the target audience, why aren’t recent maps readily available online and free in all of the surveys’ websites?

There is at least one possible reason and it’s, of course, finances.  As creatures of the state, the geological surveys can suffer from the same financial maladies that befall other state-funded agencies.  Lee Allison, the state geologist for Arizona and director of its state survey, wrote last year on his blog Arizona Geology that “it’s clear that state geological surveys across the nation are generally hurting from the economic mess.”  Despite a few states in which surveys seemed to be flourishing, Allison wrote that surveys were confronting myriad threats, including hiring freezes, pay cuts, furloughs, and, in one state, eventual elimination of the survey.

So, on this narrow issue, I would guess that the agencies confront a choice – offer maps online and free creating goodwill and support, but also depriving the hard pressed entities of a bit of needed revenue.  Perhaps, on this, the state geological surveys find themselves between . . . a rock and a hard place.

Saturday, October 30, 2010

A Bullet and A Fossil ~ Geology and the U.S. Civil War

During the U.S. Civil War, geology often set the stage and the direction for battle.  A small incident at the Battle of Wilson’s Creek (Missouri, 1861) involving a bullet and a fossil led me to this realization.  It’s embarrassing to admit it was really new to me despite having been a Civil War buff for years.  As I discovered, the intersection of geology and war has been the stuff of articles, conferences, and books (see, for example, Studies in Military Geography and Geology, edited by Douglas R. Caldwell, et al., 2004).  As one set of authors in another work puts it (citing still another author),
There are geological aspects of just about every battle on land, including those of the American Civil War.
(J.T. Hannibal and K.R. Evans, Civil War and Cultural Geology of Southwestern Missouri, Part 1:  The Geology of Wilson’s Creek Battlefield and the History of Stone Quarrying and Stone Use, in From Precambrian Rift Volcanoes to the Mississippian Shelf Margin: Geological Field Excursions in the Ozark Mountains, 2010 p. 45)
The underlying geology of the land over which the Civil War armies moved and fought is of interest, not just the geography of the surface of that terrain.  Geology explains why the landscape is the way it is and how that influenced the conflict.  It tells not only why mountains stand and rivers run where they do, but also why roads and railroads were likely to have been laid down where they were, why certain mountain gaps or passes were appropriate for moving wagons and artillery and others not, whether some hills on some battlefields were more defensible than others, and so on.  But, to be candid, the geology/geography distinction in this context is still blurry in my mind.

Even someone with only a passing knowledge of the Civil War is likely to know some portion of the litany of famous geological features of different battles, pivotal places on these battlefields which men struggled and died to attain or defend.

One of those famous geological features appears in the picture below, taken by Timothy O’Sullivan shortly after the Battle of Gettysburg in early July, 1863.  It shows Union defensive positions on Little Round Top, located to the southeast of the town of Gettysburg, Pennsylvania (Big Round Top is in the distance).  The success of Union forces in holding this rugged, steep hill on the left of the Union line during the battle was instrumental in the ultimate Union victory.  (The source of the photo is the Library of Congress.)

According to Andrew Brown, in his short and absorbing Geology and the Gettysburg Campaign (Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, Educational Series 5, 1962), Little Round Top is part of a diabase sill, an outcropping of rock that intruded perhaps 200 million years ago into the Triassic sandstone of the Gettysburg Formation.  This diabase is described in a geologic map from the Pennsylvania Geological Survey (1980) as “dark gray, medium to coarse grained.”  The material making up these diabase outcroppings is more resistant to erosion than the rock that was originally above it or surrounding it.  As a result, the outcroppings stand above the plains that fall away on each side – hence their military importance.  The Union forces occupied a fish hook-shaped position anchored at one end by Little Round Top; in effect, the entire line was on this diabase sill.

Brown's booklet outlines “the extent to which the movements of the two armies toward Gettysburg, and the battle itself, were influenced by the geology of the region in which the campaign was conducted.”  (p. 1)  These influences played out, not only in which features of the terrain on the battlefield were contested by soldiers, but also in how the armies moved across the Virginia, West Virginia, Maryland, and Pennsylvania landscapes, and why an encounter in the Gettysburg basin became increasingly likely.

The geology of the land exerts its influence in another deadly way when bedrock lies fully or nearly exposed.  The defenses in the photo above consist largely of some extant walls of piled rock and diabase boulders.  This was the largely the only protection on Little Round Top and for much of the Union position.  As a result, casualties were dramatically greater for the Union defenders of this higher ground than was the case in most other battles in which forces defended elevated positions.  Why didn’t the soldiers use trenching tools and erect more substantial defenses?  As Brown explains,  “The resistant diabase sill is so close to the surface that it was impossible for the soldiers to ‘dig in,’ . . . . “ (p. 13)

As will be evident shortly, that brutal influence of geology is a natural segue to the Battle of Wilson’s Creek, getting us closer to the genesis of this posting.  The battle took place on a rolling Missouri landscape of the western Ozarks, captured in the newspaper illustration below showing Union General Nathaniel Lyon leading a charge of the First Iowa Regiment.  A key feature of the battlefield, a ridge that would become known as Bloody Hill, is what I think is seen in the background.  (The immediate source of this image is the Library of Congress and was copied from Frank Leslie’s Illustrated Newspaper.)

In the early morning of August 10, 1861, General Lyon, tired of waiting for reinforcements to counter a growing Confederate threat to Missouri, took the fight to a numerically superior enemy commanded by Generals Benjamin McCulloch and Sterling Price camped along Wilsons Creek.  Lyon marched from Springfield and launched a surprise attack from the north.  With their initial success, Lyon’s men occupied the ridge that, over a four-hour period, would earn its new name.  But Lyon’s advance faltered on that exposed ridge in the face of artillery fire, triggering a vicious struggle for control of Bloody Hill.  The other component of Lyon’s plan, an attack by Union Colonel Franz Sigel from the south, failed.  Then Lyon fell, the first Union General to be killed in combat in the war.  The battle ended with the defeated Federal troops retreating to Springfield.

As for the geology of the event, the bedrock for much of the most contested portion of the battlefield is Lower Mississippian limestones of the Keokuk and Burlington Formation.  The 1987 geologic map for the area published by the U.S. Geological Survey describes these limestones as “light-gray to medium gray, coarse- to fine-crystalline, massive-bedded, crinoidal limestone.”  That last adjective confirms the expectation we have of limestones – there are fossils here.

This is also a karst landscape in which water has eroded the underlying limestone bedrock, creating such features as sinkholes and rocky protuberances.  This would directly affect the ebb and flow of the battle.  And geology extended here a gory hand similar to the one that was offered two years later at Gettysburg.  As Hannibal and Evans write,

The terrain, since it was developed on karst, was also uneven in places in what was at the time a fairly open area.  Glades [open areas with limestone bedrock very near the surface] . . . affected the battle, most critically at the knob that would become known as Bloody Hill.  The shallow depth to bedrock would also have an effect on the ability to dig entrenchments and gave an advantage to artillery. (emphasis added, p. 46)
I have an image of many artillery shells and bullets hitting expanses of limestone at or near the surface of Bloody Hill and elsewhere on the battlefield.  With what result?  Flying fragments of rock and metal, ricocheting bullets, and deformed spent bullets?

Earlier in this decade, the Midwest Archeological Center, part of the U.S. National Park Service undertook an archeological inventory of the Wilson’s Creek Battlefield.  This involved using metal detectors, as well as visual inspections, to identify and collect artifacts from the battle in as systematic a fashion as possible over as much of the battlefield as was accessible.  The effort, headed up by historical archaeologist Douglas Scott, resulted in an in-depth report published in 2008, entitled “The Fire Upon Us Was Terrific:”  Battlefield Archeology of Wilson’s Creek National Battlefield, Missouri (Technical Report No. 109)
Among the kinds of bullets recovered were .69 caliber spherical balls; these bullets were made of soft lead.  One of the 154 fired spherical balls found is the inspiration for this posting.  Scott’s report notes, in passing, that

One impacted ball retains an interesting impact scar that of a tiny fossil shell where it struck a piece of limestone.  (p. 40; the photo below, copied from the report, suggests what the authors saw)

Additional Source
In describing the Battle of Wilson’s Creek, I drew on Scott’s “The Fire Upon Us Was Terrific”  and, among several books, Michael Weeks’ The Complete Civil War Road Trip Guide (2009), a surprisingly detailed treatment of the events at many Civil War sites.

Sunday, October 17, 2010

Ghosts of Evolution Past

When the clock stops on a life, all things emanating from it become
precious, finite, and cordoned off for preservation.
                                ~ Jennifer Egan, Dealing With The Dead
Fall is an apt time to reflect on the past.  It’s a territory that should be labeled “Here be ghosts.”

In her short essay Dealing With The Dead (The New Yorker, October 8, 2010), novelist Jennifer Egan reveals her penchant for gathering and wearing “loans from the dead” – her grandmother’s fake pearl necklace, sweaters from her father and her stepfather.  This wearing in her daily life of mementos from departed loved ones, she calls “borrowing from the dead,” and considers it “a way of keeping them engaged in life’s daily transactions – in other words, alive.”  To me, it’s a way of calling the ghosts.

This loss of an individual person, the loss of that yin to your yang, is wrapped up in expectation.  The expectation that the person will, any minute now, walk into the room and resume the life recently ended.  I suspect Egan’s tokens keep alive those expectations, those ghosts, much longer than is true for most people.

And now for ghosts with still longer lives.

These ghosts are called by a certain autumnal smell.  Yes, there’s the usual constellation of scents that signals autumn for me, including the sweet scent of wood burning and the musty one of decaying leaves.  But, this is also the time of year when a remarkably different fall fragrance comes to mind.   For many years, during my commute to and from work, I walked past the southwest corner of the block that the U.S. Supreme Court Building occupies.  It was there, particularly on late afternoons in Indian Summers, that I’d frequently catch the whiff of that villain of autumn aromas, the one emitted by the malodorous fruit-like product of the female ginkgo (Ginkgo biloba).  Nearly everyone describes that odor by invoking either excrement or vomit (or more colorful synonyms).  A most vile seed and covering.

Last week, I retraced that commute I used to make, looking for ginkgos, sniffing for that fetid smell.  I found ginkgos, but not the ones that would have generated the odor at the corner of the Supreme Court building.  The ginkgos that I visited this time stand across the street on the lawn of the main building of the Library of Congress.  I assume these are male trees (pictured below) because there were no seeds on the trees or festering on the ground, although, it takes a very, very mature female ginkgo tree to produce the seeds.  (The small twig with leaves was lying at the foot of one of the trees.)

Here is a picture of the seeds that would have appeared were these females of the right age.  (The picture was obtained via Wikimedia Commons and is identified as the “own work” of Love Krittaya and in the public domain.) 

Has the female ginkgo that pungently punctuated my fall commute for so many years been removed?  Did she fall victim to the odor police or to all of the new security fences and other barriers that have taken over Capitol Hill?  Still, as I went over familiar ground, I found it easy to revive the memory of that smell.

The noxious odor is only one of this seed’s several offenses.  The pulp is laced with urushiol which can cause serious skin rashes, just as this chemical does when you encounter it in poison ivy.  The nut itself, though edible in small quantities, is well-armed with toxins – cyanogenic glycosides (eating uncooked nuts releases hydrogen cyanide, a perfectly nasty chemical suitable for a plot crafted by Agatha Christie) and 4-methoxypyridoxine (highly toxic for children, depriving them of vitamin B6 – not surprisingly, the top of the Google hit list for this compound is a piece entitled Ginkgo Seed Poisoning appearing in the journal Pediatrics)  The various ills of the ginkgo seed are nicely reviewed in the Washington Post’s Urban Jungle column for October 12, 2010 (on the Urban Jungle page, look for #2 (how appropriate) in October). 

When a resident of San Jose, California, recently posted a notice on Craigslist asking (well, almost begging) people to come and harvest the produce from the female ginkgo tree outside his house, he ended his posting with this desperate stipulation – “All I ask is that you take the entire fruit away with you, and not just the nuts.”  There’s no point getting technical when the smell of vomit pervades your home, but, the ginkgo is a gymnosperm, which means, I think, that technically it produces a seed with a covering, not a fruit, though, I doubt that I will be consistent with my terminology in this posting

The ginkgo tree is often referred to as a living fossil, having a lineage that, according to the University of California’s Museum of Paleontology (UCMP), traces back to the Lower Jurassic, some 190 million years ago.  During the Cretaceous Period (which ended some 65 million years ago), there were possibly a half dozen different ginkgo species.  But, then, in short order (in paleontological time), there was but one, Ginkgo adiantoides, its fossilized leaves “virtually indistinguishable from modern-day Ginkgo biloba.”  Some 9 million years ago the ginkgo slipped out of the North American fossil record, and, finally, completely disappeared from all fossils records, according to the UCMP, by the Pleistocene Epoch (beginning some 2.6 million years ago).  The many ginkgos populating our urban areas owe their existence to Buddhist monks in mountainous areas of China who cultivated the trees and may have saved the species.

But, there are startling ghosts summoned by the ginkgo seed.

In their 1982 paper in Science entitled Neotropical Anachronisms:  The Fruits the Gomphotheres Ate, Daniel Janzen and Paul Martin hypothesize that the seed dispersal systems of many Central American plant species evolved so as to give herbivore megafauna a key role.  Among these megafauna was the gomphothere, a four-tusked, large (at least some 2.5 tons) mammal that went extinct, according to the authors, along with many other megafaunal species in Central America about 10,000 years ago.  Under this hypothesis, the disappearance of these megafauna left their flora partners dependent upon less efficient alternate dispersal agents.  A prime piece of evidence is the vast overproduction of edible fruit by some tree species with the result that much of the fruit rots on the ground.  Other evidence includes the production of fruits rejected by extant dispersal agents.  Janzen and Martin argue that such fruiting traits are anachronisms, developed for a faunal partner that is now gone.

Martin and others like science writer Connie Barlow are more than happy to label the extinct faunal partners of these flora as ghosts.  Indeed, Barlow’s marvelous book exploring the Janzen/Martin hypothesis is entitled The Ghosts of Evolution:  Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms (2000).  Fruits that are too big, too tough, too toxic for contemporary dispersing agents are prime candidates for the anachronism label and Barlow writes joyfully of her exploration of these flora and their ghosts.  How can one resist this? – “Grocery stores are excellent places to encounter ghosts.  They lurk in the fruit section, feasting on anachronisms.”  (p. 7)  (Papaya and avocado are among the anachronisms being devoured.)

The concluding sentence of Janzen and Martin’s article is part of their effort to expand the potential reach of their hypothesis.  This sentence has nothing to do with the Pleistocene megafauna, but it brings us to the ginkgo and the ginkgo’s ghosts:

The vesicatory [i.e., blister causing] ripe fruits and weak-walled nuts of Ginkgo biloba might even have been evolved in association with a tough-mouthed herbivorous dinosaur that not chew its food well.  (p. 27)

Ah, the ginkgo’s ghosts – dinosaurs – which, except for the avian variety, disappeared at the end of the Cretaceous.  Barlow entitles her book’s section on the ginkgo, The Tree Who Remembers the Dinosaurs.  But, Janzen and Martin may have had the wrong ghost.  Barlow describes how Peter Del Tredici, currently Senior Research Scientist at Harvard University’s Arnold Arboretum, wrestled with this ghost and ultimately reached a slightly different conclusion.  In Barlow’s words,

The first set of target dispersers could have been small scavenging dinosaurs that lived during the Jurassic or Cretaceous.  As Del Tredici sees it, the odor of a ginkgo seed, after it has lain on the ground for a few days, may mimic rotting flesh well enough to attract scavengers of all stripes. . . . Pegging partnership on carrion-feeding rather than plant-eating dinosaurs solves one very big problem.  The seed is physically protected by a shell too thin to withstand contact with grinding machinery. . . . Herbivorous dinosaurs of the Mesozoic had two kinds of machinery that might have crushed a ginkgo seed.  Teeth would have been an obstacle in some, and for the rest, a stone-filled gizzard would have threatened even more injury.  (p. 142-143)

Barlow adds a cautionary note,

Peter Del Tredici is the first to admit the weakness of the evidence on which the dinosaur hypothesis is based.  Still, nobody has offered a better supported explanation for the mystery of the ginkgo.  (p.146)

So, there it is.  The expectant ginkgo tree, waiting for those scavenging carnivorous dinosaurs to gather up her stinking seeds and start them on their productive journey.  But now only ghosts heed the call and gather beneath her.

Thursday, October 7, 2010

Risks and Rewards of the Fossil Hunt – Evolution of a Cautionary Tale

Last week, roofers began work on a house up the street.  They moved easily along the peaks and valleys of the roof, a dangerous dance to the staccato of nail guns and the steady hum of a compressor.  They also prompted the reflection that life carries risks, some activities decidedly riskier than others.

The risks of hunting for fossils?  It certainly doesn’t rank up there with such avocational activities as free-style mountain climbing, the sport of scaling mountainsides without ropes and the other tools used by climbers more concerned about gravity.  (Tragically, a week ago, a star of this world, Kurt Albert, lost his life in a fall.)  Still, the risks of the fossil hunt, though modest, are not zero.

When I first started hunting for fossils in a serious way, I heard a cautionary tale that was then making the rounds of the local amateur paleontology clubs.  An experienced collector here on the East Coast was digging into a hillside when the soil above him collapsed, burying and killing him.  Tellers of this tale highlighted that he was collecting in a quarry alone and without permission.  They made it clear that the risks of digging deeply into a hillside went almost without saying.  He was a good man, they noted in passing.

Over time I’ve heard several other such tales of dire events on the hunt for fossils.  Yes, these stories may be salutary if they change risky behavior, but the more I’ve thought about them, the more depressing I find them because, in the telling, these accounts typically leave the life led to that point as an afterthought.

And then I found a few items on the web about Rene Savenye.  Though his story might well have the ingredients of a cautionary tale (so it began in my eyes), the more I learned about him, the more his story reassured me, reaffirmed the value of the life led, putting the events of his passing into proper perspective.

Savenye, a retired high school science teacher in British Columbia, was the quintessential citizen-scientist, a man excelling at his many and widely varied scientific interests.  He was, among many other things, an environmentalist, a mycologist (studier of fungi) and, of course, a committed amateur paleontologist.  Savenye, over his lifetime, amassed a rich and extensive collection of fossils, gaining recognition for the 1995 find of what is the second oldest fossil of a bee on record (early Eocene epoch), and the first found in Canada.  (A nice piece on Savenye appears in the online Victoria travel guide.)

On July 26, 2002, the 63 year old Savenye, hiking alone near Lake Louise and on the hunt for fossils, was struck and killed by lightning.  [Later edit:  I relied on the stories I found on the web, but see comment below for the likelihood that he was not actually hunting fossils.]  As an obituary put it, "he left us exactly the way he would have wanted, wearing his hiking boots, on top of a mountain (Mount Fairview near Lake Louise)."  (From a tribute to Savenye by the Vancouver Mycological Society.)

But, no, this is not just a cautionary tale about the weather and mountain tops.  Rather, his is a story that continues to remind me of the life, not the death.  Among the legacies he left are a dedicated cadre of former students.  Over 3,000 fossil specimens, about a third of Savenye’s first-rate fossil collection, are now a valued part of the holdings of the Royal British Columbia Museum).  In Blackie Spit Park (Surrey, British Columbia) where he worked to remove invasive plant species, he is memorialized by the Savenye Environmentally Sensitive Area.  A monument to him there reads:
A man who cared, a man who shared.
And his name lives on in another way.  That early Eocene fossil bee?  It’s a new species named in early 2003 by M.S. Engel and S.B. Archibald as Halictus? savenyei.  (The Canadian Entomologist, January/February 2003, abstract .)  Bruce Archibald, one of the authors, kindly sent me a copy of the journal article.  Its warm acknowledgement to Rene Savenye is another apt memorial:

We are grateful to the late R. Savenye for the donation of the specimen reported herein.  Rene was a well-known and loved British Columbian naturalist and avid [a]vocational paleontologist.  He donated and loaned a number of significant fossil specimens for study.  One of us (SBA) spent many pleasurable days collecting fossils with Rene.  It is a great pleasure to name this species in his honour, and we are grateful that he learned of this before his passing.  This contribution is dedicated to his memory.

Monday, September 27, 2010

Fragility of the Ecphora

It seems a minor miracle to find, amid the shell debris marking the shoreline, an even partial fossil shell from an Ecphora, an extinct sea snail or gastropod.  Paleontologists have used the Ecphora as an index fossil; the presence of specific Ecphora species can be used to date rock and other fossils.  For collectors, of whatever stripe, the Ecphora shells cast a spell by their sheer beauty which is heightened, for me, by the seemingly near impossibility of their survival as intact fossils during that final passage from burial in rock and sand to exposure.  The beaches where I hunt fossils along the Calvert Cliffs formation on the western shore of the Chesapeake are littered with little reddish brown shards of Ecphora shells, a stark reminder of the hazardous life of a fossil.  The fatality rate of these fossils after exposure to the elements must be staggering.

Ecphora are distinguished by the ribs or costae that run like exposed, elevated rails around the exterior of the shell.  The number and shape of those ribs are largely determinative of the specific species of Ecphora that one may have in hand.  The complexity and perceived delicacy of these ribs explains part of their attraction.  Often these shells have an appealing russet color, unusual in a fossilized mollusc, an attribute that also seduces the collector.

Last week, on a hunt in record breaking heat along a Chesapeake Bay beach, I came upon the specimen pictured below.  It sat exposed, wet, upright, and vulnerable amid chunks of clayey material that had fallen from the cliffs.  For seasoned collectors of Ecphora, this isn’t much, a seriously damaged specimen.  For me, it is special, as close as I’ve come to finding a complete specimen of whatever species of Ecphora.

The specimen shown above (1 3/4 inches long, 1 1/8 inches high, and 1 3/8 inches wide) I’ve identified as Ecphora tricostata Martin, an early to mid-Miocene fossil (some 15 to 17 million years ago).  The three prominent costae narrowed the field appreciably as did the location of the find – Calvert Formation.  For confirmation, I relied primarily on Ward and Gilinksy’s article entitled Ecphora (Gastropoda:  Muricidae) from the Chesapeake Group of Maryland and Virginia.  It appeared in the March 15, 1988, edition of The Academy of Natural Sciences of Philadelphia’s journal Notulae Naturae.  It fits in terms of location and its original description:  “body whorl large, with three very prominent elevated revolving ribs with a fourth rudimentary one below it on the largest specimens” (p. 3)  I detected the rudimentary rib on the specimen I found (I think it can be made out in the picture of bottom of the shell).  The other possible Ecphora with three ribs that may be found in the Calvert Formation is E. pamlico Wilson – the location fits but, among other distinguishing attributes, E. pamlico lacks the rudimentary fourth rib and has ribs that are not as prominent as those on my specimen.  (At least, that’s how I'm reading and applying the literature - the two species are clearly closely related.)

The fragility of, and fatality rate among, the Ecphora are not limited to their physical survival but also to their experience of the vicissitudes of the taxonomic process (clearly, not something unique to the Ecphora).  The naming and renaming of Ecphora species is a delightful and ongoing story

The 1980s witnessed a modest taxonomic blossoming of Ecphora species.  In particular, Druid Wilson of the Smithsonian nurtured the process in an article entitled Species of Ecphora, Including the Subgenus Stenomphalus, in the Pungo River Formation (appearing in Geology and Paleontology of the Lee Creek Mine, North Carolina, II, 1987 – full text appears on the Smithsonian website).  In this article, Wilson offered up three new species of Ecphora.

[An aside:  Because it’s germane to a tiny part of my story, the taxonomic name of each individual species given in this posting includes the name of the individual who was the original author of each species’ name.  Following proper nomenclature, if that genus and species combination were modified after initial publication, then the original author’s name is enclosed in parentheses.]

Most important for those collecting Ecphora in Maryland, Wilson stripped the state of the Ecphora quadricostata (Say).  He asserted that “[i]t is now well known that most if not all of the fossils described by [Thomas] Say in 1824 came from Virginia rather than Maryland . . . .” (p. 22)  As a result, he wrote, the “common Ecphora of the St. Marys Miocene of Maryland masquerad[ed] under the name ‘Ecphora quadricostata,’ which properly belongs to the Yorktown species of Virginia.”  (p. 23)  The specific species of Ecphora with four ribs coming from the St. Marys Formation along the Chesapeake that had been misidentified all these years, he renamed as Ecphora gardnerae.  The species name gardnerae is in honor of Julia A. Gardner (1882-1960), a geologist with the U.S. Geological Survey and a specialist in molluscs.

The following year, Ward and Gilinsky went Wilson one better, concluding that there were actually several subspecies of E. gardnerae, so the one Wilson identified was given a subspecies name and is now known as E. gardnerae gardnerae Wilson.  (p. 7)

Adding a fillip to this tale is the fact that, in 1984, the Governor of Maryland had signed legislation naming Ecphora quadricostata (Say) as the official fossil shell for the state.  Now, science had pulled out the rug from under the state.  When legislation correcting the error was enacted in 1994, the state had as its official fossil shell the “Ecphora gardnerae gardnerae (Wilson)” – well, they got it almost right.  Technically Wilson’s name shouldn’t be in parentheses.

The 1999 edition of Miocene Fossils of Maryland, by Harold E. Vokes, et al., published by the Maryland Geological Survey, identifies three Ecphora species as being found in Maryland (missing from this publication is E. pamlico Wilson).  In the illustration below, taken from Miocene Fossils of Maryland, they are #2 – E. gardnerae gardnerae Wilson, #3 – E. meganae Ward and Gilinsky, and #4 –  E. tricostata Martin.  The first shell image (#1) is a reproduction of what is purportedly among the first scientific illustrations of a U.S. fossil, published in the 1770 edition of Martin Lister's Historiae Conchyliorum.  It’s clearly an Ecphora, but which one?  The Maryland Geological Survey suggests that it's E. gardnerae gardnerae.  To others, that's certainly unclear.  Remnant of the masquerade?  (Numbers 5 and 6 are of a species of different genus of gastropod – Siphonalia devexa (Conrad).)  (The Ecphora portion of Miocene Fossils of Maryland is available on the MGS website.)

Maryland in this instance was caught by the crosscurrents coming from a vigorous scientific exploration and reexamination of the Ecphora genus.  Not sure what the excuse is for Maryland choosing, in 2004, something called the "Patuxent River Stone" as its state gem.  This has stirred controversy from the beginning.  Indeed, in 2002, legislation to do this was reported unfavorably from committee.  So, what is this stone really?  A recognized gem or not?  Agate, as its proponents label it, or, perhaps, something much more mundane like iron-stained quartz?  Ah, give me the scientific currents swirling around the beautiful Ecphora any day.
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