Tuesday, December 31, 2019

Assume the Enrolled Position

This post follows a pattern long established for this blog – a fossil serves as a portal into the lives of the people behind it.  And, on this New Year’s Eve, as I look toward the coming year, the opening topic of this post seems sadly relevant in a metaphorical sense.

When threatened, various kinds of animals, including humans, are likely to roll up into a ball.  Enrollment protects the soft underbelly, shielding vital organs, and offers a predator as small a target as possible.  For some animals, this position exposes spikes or other features that may render any bite quite difficult, if not painful.  The pill bug or roly poly probably tops most people’s list of animals that physically curl into a ball.  (These are just a couple of the many common names carried by this isopod which is, in fact, a terrestrial crustacean.)  Those of us who collect fossils are likely to consider the trilobite the posterchild for enrollment.

Trilobites are one of nature’s success stories, having endured for some 300 million years, going extinct shortly before the end of the Permian (about 252 million years ago).  Paleontologist Richard Fortey has characterized trilobites as “veritable fossil factories.”  (Trilobite:  Eyewitness to Evolution, 2000, p. 37.)  These marine arthropods molted many times during their lives, each time shedding the protective exoskeleton they’d out grown.  This process, known as ecdysis, resulted in myriad pieces or exuviae of the exoskeleton – all prime candidates for fossilizing.  Paleontologists study ecdysis in different trilobite species, describing the various ways members of each managed to shed the hard exoskeleton.  (See, for example, Ecdysis in Flexicalymene meeki (Trilobita) by Danita S. Brandt, Journal of Paleontology, Volume 67, Number 6, November 1993.)

Amid all of these exoskeleton fragments can be found many fossilized enrolled trilobites, the remains of living creatures who assumed this defensive posture and died.  From the number of trilobite fossils found in this position, it’s clear that life for these animals was no picnic.

Enrollment is a matter of serious study.  Paleontologists distinguish among several different ways that trilobites might roll up.  A key element is the relationship of the tail section (pygidium) to the head shield (cephalon) – how closely in contact they are and the extent to which the pygidium rests on or under the cephalon.  (Riccardo Levi-Setti has a nice illustration of the several named configurations of partly or fully enrolled trilobites in Trilobites, 2nd edition, 1993, p. 75.)

The conceit of this post is that, though humans can assume the enrolled position literally when threatened, we can also at times do things that, taken together, constitute metaphorical enrollment.  For the latter, I would suggest that we, in various ways, can retreat from aspects of life and raise our shields for protection.  I certainly have done it and the two scientists I profile below may have also (I’m more certain about one than the other).

Pictured below are two trilobite specimens from my collection, both prepared by Marc Behrendt.  These are Flexicalymene meeki (Foerste) trilobites from the Upper Ordovician (about 458 to 444 million years ago).  The first (top picture) is an extended specimen, exhibiting a mostly complete exoskeleton (the pygidium is somewhat folded under the thorax).  The second (second and third pictures) is a fully enrolled specimen in the posture identified as “uncoiled spiral enrollment,” which is “characteristic of the calymenids [of which F. meeki is one], where the pygidium is visible even in the enrolled condition.”  (Levi-Setti, p. 74)
These specimens were collected near Mt. Orab, Ohio.  Though their labels specify that they were found in material from the Richmond Formation, my exploration of the Ohio Geological Survey and U.S. Geological Survey websites strongly suggests that this name is no longer valid.  A likely alternative candidate is the Arnheim Formation, a rich source of enrolled trilobites, but, without any details about the location in which they were collected, there’s little more I can say about this.

There is, on the other hand, a great deal to say about the two geologists/paleontologists who figure in the scientific name for this species of trilobite.  The species name meeki honors Fielding Bradford Meek (1817-1876) and the name in parentheses is that of August Frederic Foerste (1862-1936).  The parentheses indicate that, though this species was first identified as a separate species by Foerste, its name was subsequently revised.

Foerste identified this taxon as a new species and named it in 1910.  He wrote in Preliminary Notes on Cincinnatian and Lexington Fossils of Ohio, Indiana, Kentucky, and Tennessee (Bulletin of the Scientific Laboratories of Denison University, Volume XVI, 1910):  “For the species so well described by Meek from the Cincinnatian rocks of Ohio, as Calymene senaria, the term Calymene meeki is here proposed.”  (p. 84)  I assume Foerste was referring to, among other publications, the lengthy description of C. senaria that appears in Meek’s Descriptions of Invertebrate Fossils of the Silurian and Devonian Systems (Palaeontology, Geological Survey of Ohio, Volume I, Part II, 1873, p. 173 et seq.).  Renaming the genus name to Flexicalymene was proposed in 1936 by J. Shirley in an article that I’ve not been able to obtain (Some British Trilobites of the Family Calymenidae, Quarterly Journal of the Geological Society of London, Volume 92).  Distinguishing C. meeki from C. senaria is not a task I’m prepared to tackle, though Index Fossils of North America (Hervey Woodburn Shimer and Robert Rakes Shrock, 1944, p. 645) makes it sound easy:  the former differs from the latter “in having ungrooved ribs on pygidium.”

Meek, born and raised in Madison, Indiana, apparently suffered from tuberculosis for most of his life.  (Biographies identify the Indiana birthplace, but Meek’s entries in several U.S. Censuses list his birth state as Kentucky.)  It’s unclear how much education he received, though it probably ended with elementary school.  His entry into adulthood was marked by a failed business venture that left him financially strapped.  Despite poverty and ill health, he found the energy to explore local fossils, a commitment to natural history that was recognized by geologist David Dale Owen of the U.S. Geological Survey.  For two years, Meek served as Owen’s assistant helping him to organized the surveys of Iowa, Wisconsin, and Minnesota.  For much of the 1850s, Meek worked in Albany for paleontologist James Hall, studying the paleontology of New York.  During this period, he spent two summers assisting with the geological survey of Missouri, and a third summer with geologist F.V. Hayden in the Nebraska Badlands.  In 1858, Meek joined the nascent Smithsonian Institution and stayed there until his death in 1876.  In his lifetime, he was a renowned paleontologist whose list of publications was quite staggering.

(Details on Meek's life were drawn from the following: Memoir of Fielding Bradford Meek, 1817-1876, read by Charles A White before the National Academy of Sciences, November, 1896; Trilobites, Cincinnati, and The “Cincinnati School of Paleontology,” by Danita S. Brandt and Richard Arnold Davis, in Fabulous Fossils – 300 Years of Worldwide Research on Trilobites, edited by Donald G. Mikulik, et al., New York State Museum Bulletin 507, 2007; and the Meek entry in The Megatherium Club, Smithsonian Institution Archives.)

By virtue of his work with the early state geological surveys, Meek was the first to identify many different species of ancient animals, including many trilobite species.  This was a mixed blessing.  Paleontologists Brandt and Davis have noted that “Meek has a vexing predisposition to publish preliminary descriptions of new species without illustration.”  (Trilobites, Cincinnati, and The “Cincinnati School of Paleontology,” p. 33.)   Meek was a “lumper” (one inclined to group many specimens into existing taxa), and Calymene senaria, according to Brandt and Arnold, was one of Meek’s taxonomic “buckets.”  The Ohio Calymene trilobites were rescued from this bucket by Foerste in 1910.

Though his work on the early state geological surveys and the fossils from the Nebraska Badlands is very worthy of attention, it’s Meek’s tenure at the Smithsonian that really drew me to him, and not for the work he did on fossils.  His ill health dogged him and, according to White in his memorial to the scientist, “[a]s age advanced his periods of exhaustion became more frequent and more pronounced . . . .”  (p. 79)  I wonder if this may have led him to become increasingly asocial.  If so, perhaps the Smithsonian at that time was the right place for him.  I do view that period in Meek’s life as when he may have metaphorically assumed the “enrolled position” in life.

In 1858, the Smithsonian Castle, that iconic red sandstone building on the National Mall, was only three years old and housed the entire Institution, including administrative offices, laboratories, and storage space.  It also provided living quarters to the Smithsonian Secretary and his family.  Significantly for Meek, the building had other unused rooms some of which were allocated to bachelor scientists as apartments.  A descriptive entry by the Smithsonian Institution Archives puts it this way, Meek “lived with his cat in a tiny room under the stairs in the North Tower of the Smithsonian Castle from 1858 until his death.”  This is from the caption to picture 4 of Meek in his Megatherium Club entry.  The picture is seen below and was downloaded from the Smithsonian Institution Archives website.  It has no known copyright restrictions (Smithsonian Institution Archives, Record Unit 95, Box 17, Folder: 2).

One might question my assumption that Meek was “enrolled” because, by virtue of living in the Castle, he became a member of the Megatherium Club, that exuberant coterie of “eccentric” (the adjective applied by the Smithsonian Institution Archives) naturalists of the Institution.  They were a wild bunch, known to drink and play music at all hours.
When the club members lived in the Castle they often times drank beer at night and had sack races down its halls. It has also been noted that if the men were feeling up to it, and drank enough that night, they would sneak outside to the windows of the Henry daughters and serenade them.  (Smithsonian Institution Archives)
The “Henry daughters” were the daughters of Smithsonian Secretary Joseph Henry.

Although this association might seem out of character for Meek, reading between the lines of a letter naturalist Robert Kennicott, a cofounder of the Club, wrote home describing its members in detail, the picture I have of Meek remains intact.  Clearly, this was a group that could embrace the unconventional among its members, and, I suspect, Meek probably did not partake in many of the Club’s hijinks.

In his letter, Kennicott began his profile of Meek by calling him “a queer character,” but added, “he is a very excellent and Honorable gentleman with fine feelings and extremely modest though he is now one of our best Paleontologists . . . .”  Tellingly, Kennicott went on to write:
Meek is some 40 years old but quite fresh and boyish in feeling like all naturalists.  He is very deaf and this has made him extremely retiring.  He never goes into society and the uninitiated never know what an excellent fellow he is.  He is wholly devoted to science and scarce thinks of anything else.  (Kennecott, letter sent February 17, 1863 and addressed to “Folks at Home.”)
I love the line “quite fresh and boyish in feeling like all naturalists.”  Would that this always be true.

This other item from the Smithsonian Institution Archives strikes a particularly poignant note for Fielding Meek.  It's a pencil drawing he made of his cat, doing what all cats love to do.  He inscribed it with:  "This is all the family I have."

This picture was downloaded from the Smithsonian Institution Archives website.  It has no known copyright restrictions (Smithsonian Institution Archives, ID:  92-15019, Record Unit 7065, Box 8, Folder: 12).

August Foerste was born and grew up in Dayton, Ohio, and lived nearly all of his adult life there.  He spent his early years “roaming the swamp and woodland of Oakwood [Ohio] and the area south of Dayton.”  (Michael R. Sandy, Geologic Glimpses From Around the World – The Geology of Monuments in Woodland Cemetery and Arboretum, Dayton, Ohio:  A Self-Guided Tour, Guidebook No. 8, prepared for the 1992 Annual Meeting of the Geological Society of America, p.19.)  He earned a B.A. from Denison University (Granville, Ohio) in 1887 and then journeyed east for his graduate studies, receiving a Master’s degree in 1888, and a Ph.D. in geology from Harvard University (Cambridge, Massachusetts) in 1890.  He then spent a couple of years in Europe, studying in Heidelberg, Germany, and Paris, France.  Throughout his undergraduate and graduate years, Foerste demonstrated strong research and writing skills.  At Denison, he co-founded the Bulletin of the Scientific Laboratories of Denison University which continued publishing into the 1920s.  Beginning perhaps as soon as 1887, Foerste served as an assistant with the U.S. Geological Survey.  Following his European stay, Foerste went back to Dayton and taught physics and botany at Steele High School for some 38 years, until his retirement in 1932.  At that juncture, he, once again went east, moving to Washington, D.C., where he joined the ranks of paleontologists at the Smithsonian Institution and stayed until his death in 1936.  I find no record of his having ever married.

Throughout his adult life, Foerste published often.  He was particularly interested in “the restudy, redescription, illustration, and naming of new species of invertebrate fossils not adequately described or not designated as separate species in their original publications [citation omitted].”  (Brandt and Davis, Trilobites, Cincinnati, and The “Cincinnati School of Paleontology,” p. 38.)  Clearly, the man was a taxonomic “splitter,” finding multiple species among specimens that “lumpers” might group together.  His work on the F. meeki is a case in point.

Many volumes of his field notes are available in a digitized form on the Biodiversity Heritage Library.  I looked through them in search of any substantive references to Calymene meeki (i.e., the Ohio version of Calymene senaria) but came up empty.  The field notes, from the late 1880s through the early 1910s (many are undated), offer a mixture of data.  Most often Foerste recorded details about geological locations, replete with landmarks and descriptions of the rocks found at different elevations at these sites.  Sometimes, he drew stratigraphic columns of outcrops.  On occasion, he sketched the fossils he found.  He kept me reading through notebooks even when they held relatively little interest because at unexpected points he deviated dramatically from his scientific mission.  For instance, there’s the field notebook in which, out of the blue, he wrote down a series of candy recipes.  My favorite digression is the one for Sunday, July 25 that appears in a notebook to which no year is assigned (probably 1887, 1909 or 1915, years in which July 25th is on a Sunday).  Amid day-to-day descriptions of different geological locations around Irvington, Kentucky, Foerste begins this date’s entry with the following list:

2 shirts
1 drawers
2 handkerchiefs
1 stockings

Clothing he needed?  Clothing sent for cleaning?  Priceless.  (Adrianna Marroquin has written a wonderful post (December 8, 2017) on Foerste’s field notes for the Biodiversity Heritage Blog.  It’s good fun.)

When I began to explore Foerste’s life, I was convinced that rather early in his adult life he’d disengaged from some parts of life by virtue of narrowing his horizons to the familiar confines of Dayton, Ohio.  I sensed this was likely principally because I had trouble understanding why in the world, after attending Harvard, spending two years in exciting European cities, and beginning to establish his professional scientific reputation, he chose to spend his professional career teaching high school in his hometown.

There’s no condescension in this comment.  I have taught elementary school and others in my family are currently or were elementary or high school teachers.  Pre-collegiate teaching is a challenging profession that should be much more honored than it is.  Nevertheless, Foerste’s decision to teach high school in Dayton, Ohio, initially struck me as designed to remove him from the academic and scientific mainstream.

In his defense, Brandt and Davis offer paleontologist Ray S. Bassler’s explanation for Foerste’s choice:  he followed this path “because he felt the position interfered less with his scientific research than would a more conspicuous college position.”  (p. 38, quoting the Memorial of August F. Foerste, Proceedings of the Geological Society of America for 1936, p. 145)  The evidence would suggest that this may well have been true.  Foerste, the high school teacher, remained very active in geology and paleontology at a professional level throughout his adulthood.  He was associated with several state geological surveys, worked with various nationally recognized paleontologists such as Edward Oscar Ulrich, and “earned the reputation in Europe and America as one of the leading paleontologists and geologists of his time.”  (Sandy, p. 19)

(Still, a small voice in my ear suggests there may have been more to it than that.)

I am particularly taken by this picture from Foerste’s time at the Smithsonian.

Foerste is on the left while paleontologist Amadeus W. Grabau is in the middle (he was a coauthor of the initial iteration of Index Fossils of North America), and E.O. Ulrich is happily gesturing on the right.  This picture was downloaded from the Smithsonian Institution Archives website and has no known copyright restrictions (Smithsonian Institution Archives, Record Unit 7177, Image No. SIA2018-055242).

In the end, to be honest, my fixation on enrollment, real and metaphorical, stems largely from own sense that this is the posture I will be assuming for much of the coming year, a year which is likely to be devastatingly challenging.

Saturday, November 30, 2019

Origami ~ Crossing Lines

Once again I’m relying on the broad portfolio I gave this blog at its inception (now 300 posts ago).  If I can draw even the most tangential link to some aspect of natural history (or, even better, fossils), then I’m okay (mostly).  And this post begins (very briefly) with dinosaurs and ends up with one monstrous ancient animal fashioned using origami, a model that reflects the line or boundary crossings in this art form that I write about.

When origamist Peter Engel, who trained as an architect, visited the origami master Akira Yoshizawa, he asked the master whether he’d folded dinosaurs.  Yoshizawa replied, “All of them!  Tyrannosaurus rex.  Iguanodon.  Triceratops.  Brontosaurus.  Stegosaurus.  I’d show them to you, but they’re in the attic.”  (Folding the Universe:  Origami From Angelfish to Zen (1989), p. 33.)  There!  In my mind, I’ve justified this post, and I do return to ancient creatures at the end.

In the middle of the 20th century, Yoshizawa almost single handedly remade origami, creating new models more complex than had been seen heretofore and in staggering numbers.  So it was no wonder that Engel described his visit in terms appropriate for an acolyte gaining audience with a high priest.  It was a religious experience.  Ultimately Yoshizawa was not alone in breaking through the traditional boundaries that had contained origami.  For what might be labeled the origami revolution of the mid- to late-20th century, Yoshizawa not only broke through traditional barriers to show what was possible, but he also played a central role in codifying the symbols and notations used to record folds in origami instructions.  This powerful development enabled paper folders to follow instructions regardless of the language they spoke.  And so the revolution spread.

In the revolution, origami crossed myriad boundaries and is still crossing them:  from the relatively abstract to the very concrete (particularly objects from natural history), from the simple to the extremely complex, from the artistic to the practical, from art to mathematics and back to art, from the stasis of tradition to a state of rapid, continuous evolution.

Much of my writing for this blog has sought to cross lines that normally compartmentalize the amateur from the professional, the collector from the scientist.  I have tried to move beyond visceral reactions to fossils and other aspects of natural history to explore the all-important backstory.  It’s in the traversing of such boundaries that the context becomes broader and richer, and, concomitantly, the original object more meaningful.

As for origami, I am just a dabbler, decidedly an amateur, capable of only creating simple figures (from cootie-catchers to cranes, but not much beyond).  My frustration level rises markedly as the number of steps in a pattern grows, and it’s in those lengthy instructions that the true richness of the art form lies.  Despite my inability to cross the boundary into the complex, I find origami endlessly fascinating.

Origami (from the Japanese for to fold and paper) dates back centuries in Japan, though similar art forms appear to have emerged independently elsewhere.  Given the stability in designs over much of origami’s existence, the potential for making figures from folding a single sheet of paper would seem to have been exhausted.  Then a flowering occurred.  Traditional instructions of a limited number of steps blossomed into ones with hundreds of steps.  As physicist Robert J. Lang, one of the key players in this revolution, wrote in his The Complete Book of Origami:  Step-by-Step Instructions in Over 1000 Diagrams (1988), “The detail in complex folds can be astounding, for the artists of the modern era have carried origami to unprecedented heights of realism and complexity.”  (p. 1.)

The revolution involved many things.  Even more than by the ability to chronicle instructions in a near-universal language (see Yoshizawa above), the revolution was fueled by rigorous mathematical analysis of the patterns of creases and folds recorded in the paper from the action of origami creation.  As writer Beth Jensen noted in her profile of Lang for Smithsonian Magazine (Into the Fold:  Physicist Robert Land Has Taken the Ancient Art of Origami to New Dimensions, June 2007), “Lang and others use analytical geometry, linear algebra, calculus and graph theory to solve origami problems.”  Technology has a role to play as well.  Lang wrote a computer program that can generate the crease and fold patterns needed to fashion complex figures.  Another program can then derive the various sequence of steps that might be needed to create such models.  These programs don’t do all of the work.  Indeed, as Lang has observed, although parts of origami can be captured by equations, “the artistic aspect will never be captured in equations.”  (Jensen, Into the Fold.)

Art to mathematics back to art as the paper folder strives to inch closer to the essence of the organism being depicted.

For more on Lang, I highly recommended the article by Susan Orlean titled The Origami Lab:  Why a Physicist Dropped Everything for Paper Folding, The New Yorker, February 11, 2007, and Lang’s TED Talk of February 2008.  The Mitsubishi car commercial he runs in the middle of the talk is worth the price of admission.

As I’ve noted, for some, the appreciation of origami borders on (and perhaps embraces) a religious fervor.  In Folding the Universe, Engel begins his exploration of the connections of origami to nature, science, and, indeed, life, by quoting artist M.C. Escher.  Escher was quite taken by the patterns in the tiles decorating the Alhambra.  Applying these patterns to figures from nature was, he believed, a “crossing of the divide between abstract and concrete representations” (as quoted in Engel, p. 3).  The theme of crossing divides underlies Engel’s book, and it’s at the heart of his fascination with the art form.  Taking a single sheet of paper and transforming it into a object calls on the folder to cross a divide.  As Engel would have it:
Crossing the divide is a spiritual act. . . .  In the paper, as in the primordial cosmic soup, chaos yields to order, formlessness to form, darkness to light.  (p. 5)
My appreciation doesn’t rise to such heights, but that concept of crossing boundaries or lines attracts me.  As I've already stated, my folding fails to cross the line that separates simple, relatively abstract representations of nature from complex near approximations of reality.  For the former, here are several of my origami pieces created by following very simple, long-established patterns.  Lest they be too abstract or crude, they are a mouse and a duck.

In contrast, a post-revolution creation by Fumiaki Kawahata appears below.

(This image was taken from Wikimedia Commons and purports to be in the public domain and licensed under the Creative Commons Attribution 2.0 Generic license.)  []

Origami has crossed from the artistic to the practical.  Lang, in his TED Talk, considers an aspect of this process.  Origami, by developing techniques for folding and compressing a sheet of material into a particular shape, has generated approaches that are applicable to real world concerns.  How, for example, can one efficiently and effectively pack an airbag into the dashboard of a car?  Origami has contributed to solving that challenge, as it has to addressing the problem of folding a stent for transport through a blood vessel until it reaches the place where it can be unfolded and do its job.  Origami has also been involved in development of ways to get the broad array of a telescope into space when, to reach space, it has to fit within the relatively narrow confines of a spacecraft’s cargo hold.

The trail of ancient animals leads from Yoshizawa to Lang, from those that would fit comfortably (probably in small boxes) in the attic in Yoshizawa’s house to a life-size Pteranodon that majestically soars in the high, far reaches of the ceiling in the Dawson Gallery of McGill University’s Redpath Museum.  The latter is one of Lang’s “monumental origami” creations.  Such origami is described on Lang’s website.
One of the characteristics of origami is that it embodies a contradiction:  how can such an intricate, detailed object come from a single uncut square?  Monumental origami takes that contradiction and expands upon it. Conventional, bread-box-sized-or-smaller origami challenges the observer:  is it possible from a single sheet?  Monumental origami makes the same challenge, but adds the element of size to the mix.
The Pteranodon was a flying reptile that flew the skies of the Cretaceous (possibly from about 72 to 89 million years ago).  Though in some Pteranodon species, the wingspan stretched to more than 23 feet, the span in the model that Lang made for the Redpath Museum comes in at merely 16 feet.  Here it is in all its glory:

(This image is reproduced with the generous permission of the Redpath Museum and appears on its website.)

Monday, October 21, 2019

Algae: The Simple Is Complex

Writer Ruth Kassinger praises algae unstintingly in her new book, Slime:  How Algae Created Us, Plague Us, and Just Might Save Us (2019).  They are, she asserts, “the most powerful organisms on the planet” and, to them, we owe our existence.

Though we humans are here due to the work of a host of other entities and a long series of fortuitous events as well, I will grant Kassinger her point.  In perhaps their most signal contribution to the planet, algae, through the chemical magic of photosynthesis, added oxygen to an atmosphere that, heretofore, had been inimical to multicellular life.  And their crucial gifts go well beyond oxygen.  There’s the production of soil, without which the colonization of land by plants was a non-starter.  Plants, themselves, evolved from the charophytes (a taxon of green microalgae).  Take algae out of the food chain and animal life is done for.  The development of the large Homo sapiens brain can be attributed in part, Kassinger argues, to algae.  Early hominins living along shorelines had diets rich in “brain-selective nutrients,” those minerals and fatty acids critical for brain development.  Central to this diet was probably seaweed.  Of increasing importance, there’s the sequestration of carbon dioxide in their bodies that accumulate in untold numbers on the ocean floors.  Coral reefs?  Not without algae.  The list goes on.

So, what are algae?  This turns out to be a complicated question to which there is no consensus answer.  Kassinger fudges this:  “Algae (and the singular alga) is a catchall term, a name for a group of diverse organisms.”  (p.xii)  She notes that all do (or did) photosynthesize, though they are not plants.  Paleontologist Steven M. Stanley in Earth System History (2nd edition, 2005) places algae in the Kingdom Protista.  The catchall nature of the label stems from the fact that the different algal taxa did not evolve from a common ancestor.  Kassinger describes three main groups:  single-celled blue-green algae or cyanobacteria; single-celled microalgae; and multicellular macroalgae (the seaweeds).

She tells of the good, the bad, and the ugly of algae.  I’ve already cited many of their positive natural contributions, but, as Slime documents, there are a host efforts underway to harness the power of algae to address multiple needs of the planet and its inhabitants.  These range from enlisting algae in cleaning polluted waters, to developing more eco-friendly plastic polymers, to producing algae oil (growing the algae needed for this would take carbon dioxide out of the atmosphere), to introducing more algae-based food stuffs into our and other animals’ diets.

As powerful as algae are for good, their capacity to wreak havoc must enter into the equation.  When these organisms “bloom” or run wild, often sparked by the excess nutrients we are putting into our bodies of water, they can create massive dead zones, killing or driving away other living creatures, releasing toxins, and ruining scenic beaches.  It’s not a pretty picture.

Kassinger’s book is a forceful statement on behalf of algae’s centrality to life on Earth, though she is less persuasive in asserting that they “just might save us” from the existential threats arising from climate change.

I wish I could endorse the book whole heartedly.  Kassinger certainly can distill complex topics, presenting them in ways that the lay person can understand and appreciate.  Her topic has deep appeal and the reader comes away having learned a great deal.  My primary complaint is that she has succumbed to the temptation facing (and undoing) many writers of popular science:  making themselves heroes of their stories, forcing their subject matter to share and, at times, relinquish the spotlight.

In Slime, the personal anecdotes of her journey in pursuit of information about algae finally wore thin for this reader.  I really wasn’t interested in, say, her scuba diving lessons or the challenges of staying warm on board a boat traveling over open water.  Beyond that, I think her editor failed her because, when some issue emerges as important for her research, Kassinger will use the same or similar language to explain to the reader why she’s now in some other part of the world:  “In search of answers, I find myself,  . . . .”  (p. 63) or “Nova Scotia is where I’ve come to investigate . . . .” (p. 106) or the phrase “which is why . . . .” (this last turns up at least four times – at pages 35, 81, 171, and 196 – to introduce a new location and some more personal anecdotes).

Yet, Kassinger probably achieves her aim.  Having read the book, I certainly am much more aware of algae and what they have done, and are doing, for me.  I’ve responded to the book in some small ways.  For instance, seaweed has a bit more of a role in my diet.

The book’s strongest impact on me came from the chapters that Kassinger devotes to lichens.  She introduced me to these surprising entities, marvelous in their composition and their impact on the planet.  Their range of structures and color is remarkable.  The label “lichen” applies not to organisms grouped by structure or color, but by a symbiotic relationship, a way of life, that has married algae and fungi.  The algae, often termed a “photobiont” in this association, uses its photosynthetic power to manufacture sugars and other carbohydrates, much of which are absorbed by the fungi with which they reside.  The fungi, in turn, provide the algae an environment replete with critical moisture, shields against harmful ultraviolet rays, and toxins that ward off predatory animals.  Though there is no typical arrangement of algae and fungi in lichens, the illustration below of the interior of a simplified foliose lichen (one of the main groupings of these organisms) captures some of the essence of the lichen structure.  This illustration is my own but was guided by those that appear in Joe Walewski’s Lichens of the North Woods (2007, a useful volume though limited in scope to the “North Woods,” an area surrounding Lakes Superior and Huron).  This illustration is of a view I have not seen in person though I tried to do so (my microscopes and dissecting equipment were not up to the task).
Lichens are organized into several groups:  crustose lichens which lie very flat against the substrate on which they are affixed; foliose lichens which are much more three-dimensional with lobed growths and some separation from the substrate on which live (two examples of such lichens are discussed shortly); fruticose lichens which, as Kassinger notes, “often resemble miniature tumbleweeds and attach to a substrate as a single point.”  (p. 37)  In the massive and gorgeously illustrated Lichens of North America (2001), Irwin M. Brodo and his co-authors identify a fourth group of lichens, the squamulose which are “intermediate between foliose and crustose growth forms.”  (p. 17)

To call a relationship symbiotic suggests (to me, at least) a relative balance in the partnership, one that appears to be somewhat lacking in lichens.  Yes, the different kinds of organisms involved benefit, but there are aspects that clearly favor the fungi.  Quite frequently in this relationship, according Brodo et al., the fungi is killing the enveloped algae.  Thankfully, that murderous impulse is somewhat more than offset by the algae’s rate of reproduction.

Which raises the question of reproduction in such an entity made up of two different kinds of organisms with different reproductive strategies.  As a result, it’s not surprising that lichens engage in a variety of ways of reproducing.  One approach is to paper over the reproductive differences altogether.  Kassinger observes, that “many lichens stake out new territory asexually.  When a fragment detaches and blows away, if it lands in a similar location, it attaches and starts growing as a new individual.”  (p. 37-38)  For other lichen species, asexual reproduction is more deliberate and complicated.  These species create little balls (called soredia), each consisting of a single algae surrounded by fungi filaments.  If these reproductive spheres are detached from the lichen and come to rest in a hospitable environment, a new lichen can grow.  The challenges of asexual reproduction pale when compared to the sexual reproductive strategy some lichen species pursue.  The fungi in most of these lichens produce spores which begin as sex cells (gametes) and then, after fusing with other sex cells, are released.  But these spores, cast to the winds, will create a new lichen only if they happen to land on an alga of a specific, requisite species.  Here the fungi appear to be playing against long odds, though producing countless spores in the process helps shift the odds a bit.

Lichens literally are everywhere.  They are extremophiles.  Brodo and his colleagues write, “They are found from the poles to the tropics, from the intertidal zones to the peaks of mountains, and on every kind of surface from soil, rock, and tree bark to the backs of living insects!”  (p. 3)  To call them an evolutionary success story is to undersell their accomplishment.  There are nearly 14,000 different species covering some six percent of Earth’s surface.  Lichens are the sine qua non for soil.  Without them, plants could not have invaded land.  Those lichens that employ rock as a substrate engage in a slow, very slow process of eroding the rock into soil.  Their anchoring filaments penetrate cracks in the rocks and, as the weather alternatively moistens the lichens, expanding their anchoring filaments, and then dries them out, the substrate is broken up.  Despite the seeming inefficiency of this method of creating soil, Kassinger counters that “rocks covered by lichens disintegrate ten times faster than they would otherwise.”  (p. 32)

Lichens are affected profoundly by air quality.  The diversity of species in a location is a gauge of how polluted its atmosphere is.  Urban areas host very few species, and my suburban neighborhood outside of Washington, D.C., seems to be home to only a handful of lichen species.  That said, I am only beginning to search for lichens and, as I’ve noted previously on this blog, the success of any quest in nature depends largely on having internalized appropriate “search images.”  Too often, the neophyte can be staring at the object of his or her quest and miss it entirely.  So, I suspect there are more lichen species here than I have noticed.  Just the other day, I spotted a lichen species new to me living on the ledge outside my second floor bathroom window.

The two species described below are ones that I found on twigs that had fallen from deciduous trees.

The first I’ve identified as the foliose lichen Parmotrema crinitum, the salted ruffle lichen.  The first picture shows the entire specimen.  The subsequent images are closeups of different areas of the specimen.  I continue to be amazed at the microworld that unfolds as the exterior of a lichen is magnified.

If I’m wrong in this identification, then my defense is that I was misled by the lichen’s gray-green color, lobed shape, brown underside near the lobe edges, and, most importantly, the cilia, those hair-like filaments that come out of the edges of the lichen’s lobes in abundance.

This next lichen is another foliose, tree-dwelling species, Physcia millegrana, the mealy rosette lichen.

 I have to admit that this identification relies mostly on gazing at the pictures in Brodo’s lichen bible.  The pale gray color and the thin lobes favor this ID.  I do not know what the green circular patches are.  Clearly, I am a neophyte at this but I am avoiding the beginner’s tendency to assume that any find is exceptional.  P. millegrana is, according to Brodo, “among the most common bark-dwelling lichens in eastern North America, even occurring close to urban areas on cultivated as well as wild deciduous trees.”  (p. 555)

Lichens, a complex world beckons.

Saturday, September 28, 2019

Function For This Form

Fossil in hand, the question nearly always arises:  why is this specimen shaped the way it is?  The initial presumption is that form reflects function which is not always true.  As this post explores, there are times when a function follows form.

Exploring the interplay of form and function helps turn fossil collecting from an impulsive effort simply to amass neat specimens into an intellectual activity meriting the label “amateur paleontology.”

The gift from a friend of some fossil mollusc shells found along the St. Marys River, Maryland, prompted research to explore why the two bivalve shells shown below sport such robust, overarching concentric ribs.  These shells, collected in the St. Marys Formation, Windmill Point Member, are from the extinct species Lirophora alveata which, according to Fossilworks, lived between 11.608 and 7.246 million years ago (Late Miocene).

In 1903, paleontologist William Healey Dall described L. alveata succinctly:
This fine species is readily recognized by its high, trigonal form, few high, even, recurved concentric ribs, and absence of radial sculpture.  (Contributions to the Tertiary Fauna of Florida, Transactions of the Wagner Free Institute of Science, Volume III, Part VI, October, 1903, p. 1298.)
I had never considered the function of concentric ribs on mollusc shells.  Based on a quick scan of a modern guide to shells, it would appear that concentric ribs aren’t uncommon among bivalve species.  Evolutionary biologist Geerat Vermeij, in his always rewarding A Natural History of Shells (1993), considers the role of shell ornamentation, such as ribs, or the lack thereof, in the burrowing process for infaunal molluscs (those that live in bottom sediment).  Burrowing molluscs face an important challenge:  keep from being exposed as the water’s currents move sediment away.  There are two responses to this challenge.  The first is to burrow quickly and deeply.  For that, smooth shells, those lacking ornamentation, do well.  The second is for the mollusc to burrow shallowly and try to stabilize the surrounding mud and sand, that is, keep such material from being scoured away.  Vermeij notes that certain kinds of shell shapes evolved to accomplish that stabilizing, including “strong concentric ribs” in infaunal clam families, including the Veneridae to which the Lirophora belong.

I would think that the concentric ornamentation might offer more impediment to burrowing than radiating ornamentation.  As the mollusc’s “foot” works at sediment to bury its shell, radiating structures might contribute to the burrowing process, allowing the shell to cut through the mud and sand, and moving the material away.  Concentric ornamentation could be rather counterproductive for that.  Do bivalves with radiating ribs bury themselves deeper than those with concentric ribs?

From this, one might conclude that stability in sediment is the reason this Miocene bivalve featured those distinctive concentric ribs.  Well, it’s probably not the only reason.

Two paleontologists, Adiël A. Klompmaker and Patricia H. Kelley, in an interesting paper titled Shell Ornamentation as a Likely Exaptation:  Evidence from Predatory Drilling on Cenozoic Bivalves (Paleobiology, Volume 41, Number 1, 2014) take us a level deeper into this.  The authors observe that ornamentation on shells, such as ribs, might serve a number of functions, such as:
maintaining a stable life position in the sediment, burrowing, shell strengthening, directing inhalant and exhalant currents, and protecting against predators. (p. 187)
Their research focus is “the degree to which ornamentation is effective against drilling predation” on “several bivalve species with varying strengths of smooth-topped concentric ribs.”  (p. 188)

Ah, another possible function for this form.

One of the species they studied is the extant Lirophora latilirata which, as the picture below shows, is certainly related to the extinct L. alveata.

(This picture is reproduced under the Creative Commons Attribution-NonCommercial ShareAlike 4.0 International license.  This picture was posted by cyric to iNaturalist and can be found here.)

The take-away from their paper is that concentric ribs, such as those featured on Lirophora species (both extinct and extant), defend these bivalves from predation by boring gastropods.  Such ribs appear to be an efficient and economical way for these animals to strengthen their shell without investing the resources required to thicken the entire shell.  Not only are dense concentric ribs difficult to drill through, they minimize the amount of exposed, unstrengthened shell that predators might reach and drill into.

Based on an examination of the two L. alveata specimens shown above, I would go further for this species and offer the following hypothesis.  The outer edges of the curved ribs of L. alveata are not as thick as the bulk of the structures arising from the shell, perhaps reflecting a further economy in the investment of resources to generate ribs.  These thinner overhangs might be sufficient to serve a defensive function, helping to keep snails from gaining access to the shell surfaces between the ribs.  Further, though predators might drill through them with less effort, these predators would have to make a further effort to actually reach the shell surface below.  This hypothesis probably applies as well to the extant L. latilirata pictured immediately above.

There is more to extract from this study relevant to this exploration of concentric ribs.  The authors contend that there is evidence that concentric ribs are a defensive “exaptation,” not an “adaptation.”  Klompmaker  and Kelley distinguish the two terms:
adaptations are features built by natural selection for their current role, whereas exaptation refers to characters that evolved for other usages or for no particular function and were co-opted later for their current role.  (p. 188)
The authors believe that the timing of the emergence of concentric ornamentation in bivalves (first appearing in the Paleozoic and proliferating in the Mesozoic), which preceded the appearance of significant drilling by predatory gastropods, suggests that the defensive role of those ribs came after their initial appearance.  According to this line of argument, because the ribs did not evolve in response to drilling, the defensive function they now serve is an exaptation.  If true, that means that such ribs were first generated by natural selection to serve a different function (stability for shallow burrowing?) or for no discernable function (not every feature of an organism is necessarily serving a current or even a past function).

In the end, it’s always satisfying to find a plausible explanation for the form of a fossil or some feature on it. In this instance, there’s the added bonus that, although the form was driven by one function, another function apparently followed.  In other words, build it (for some function or none) and a function might come.

Friday, August 30, 2019

Celebrating Flight

Flight.  My summer has been dominated by consideration of the beauty and challenges of flight.  In typical fashion, in this post I have awkwardly juxtaposed two interests of mine.  So, at its end, this post dashes from dragonflies to biplanes.  Be warned.

Inspired by the exquisite photographs of dragonflies taken by a friend, I’ve spent far too much time this summer in pursuit of these insects with little to show for the effort.  Dragonflies are members of the Odonata order, along with damselflies, and specifically of the infraorder Anisoptera.  (Infraorder, a new term for me, is a taxonomic grouping below a suborder and above a superfamily.  I assume this is a generally accepted taxonomic grouping term.)  Dragonflies are quite ancient; the Protodonata appear in the Late Carboniferous, some 325 million years ago.  Sporting a monstrously large wingspan that could reach some 30 inches, the Protodonata had key similarities (though not size) to today’s dragonflies, but they went extinct during the Triassic.  True Odonata insects appeared during the Permian, over 250 million years ago, and have remained largely unchanged since.  (Much of this discussion is based on Introduction to the Odonata, provided by the University of California Museum of Paleontology.)

The image below shows a dragonfly fossil (Tarsophlebia eximia) from the Late Jurassic (between 150 and 145 million years ago) which was found in Germany’s Solnhofen limestone.

(Wikimedia Commons reports this image to be in the public domain.)

It is impossible I think to spend any time watching dragonflies and not consider what it means to fly.  These implacably hungry carnivorous insects are on a continuous hunt as they cut through the air in abrupt slashes, darting with purpose.  Their sharp aerial dances (remarkably lethal for their prey) are punctuated with moments of hovering.  Then all this ceases for often long periods of motionless rest on, say, a plant leaf or stem (or, even, a clothesline or the back of a mottled plastic lawn chair).  During these pauses, their four wings remain spread, open to the sun and to inspection.  These are the opportunities to try and capture the image of this ancient creature.

Two of my more successful pictures of dragonflies appear below.  The first shows a female dragonfly on a clothesline and the second a male on a plastic lawn chair.  Both specimens are of the species Pachydiplax longipennis, commonly called Blue Dasher.  These individuals are roughly 1.5 inches long from head to tail and exhibit sexual dimorphism in their color differences.

Dragonflies’ heads are mostly eyes (clearly, this is a predator) which can provide a wonderful canvas for coloring.  The distinctive wings are attached to the second and third sections of the thorax.  The long, needle-like abdomen offers another place for distinctive colors.

As entomologist Scott Richard Shaw, in his fascinating book Planet of the Bugs:  Evolution and the Rise of Insects (2014) (reviewed previously in this blog), observes, the extended-wing posture of dragonflies at rest is a telltale sign that these are paleopteran insects.  That is, dragonflies along with mayflies, are so-called “old-winged” insects.  As he writes:
The most ancient wing style – a flat panel of skeletal material set into a membranous area at the top of the thorax – was very simple but highly efficient, and some modern insects such as mayflies and dragonflies still sport it.  (p. 81)
The old-wing configuration, a breathtaking innovation when it first appeared, involves the snapping of the animal’s wings.  The wing upstroke is generated by muscles internal to the thorax (not attached to the wings) which change its shape causing the upward movement of the wings.  The wing downstroke is propelled by muscles directly connected to the wings.  It’s these flight muscles that allow for some tilting of the wings necessary for navigation.

Most obviously, the old-wing construction prevents these insects from doing what the myriad neoptera (new-winged) insects of today take for granted:  they can “twist their wings at the base, fold them back over their body, and put them away” (p 88), making them smaller targets for predators.  (I'm puzzled, though, by the photograph I took of the female shown above.  What were her wings doing and how did they do that?  After posing for the picture, she flew off without a hitch.)

Shaw devotes a chapter to an exploration of insect flight.  He notes there are some fundamental questions which remain open to debate, but he is not shy about positing the answers he believes make the most sense.  Though he considers how wings evolved, what interests me more is what he has to say about why they came into being.

For millions of years in ancient time, insects were the fliers, the animals having airspace to themselves.  Flight appears at a time in the Carboniferous (say 320 million years ago) when trees become abundant.  Rather than believe that the early insects climbed tall plants in search of edible parts of the plants and then came to launch themselves into the air, relying on body parts conducive to gliding, Shaw asks, Why would they make that climb in the first place since seeds and spores would eventually fall to the ground?  He argues that insects would have been prompted to climb in order to reach sunlight, they are, after all, cold blooded.  Protowings would then serve as “solar panels” –
[t]he larger structural veins of the wings are hollow, so blood blows into them, allowing heat to transfer back into the body.  Even small protowings would have had the potential to transfer valuable heat, possibly before the panels could be used for flight.  (p. 78)
That, in his estimation, is a more persuasive reason for climbing plants in the first place.  But, at some juncture, he postulates it became easier to descend the plants by pushing off into the air relying on protowings for a safe descent.  Further development of wings would have been prompted by, among other reasons, courtship and mating (wings can feature colors and patterns), camouflage (colors and patterns), escape from predators, and dispersal of the taxon.

A wrenching pivot happens right here.

It’s only been appropriate in this year of 2019 to be thinking about flight, but not necessarily of the insect kind, rather, of the human kind.

I’ll try to make this change of course less jarring by referencing writer Jay Spenser who, in The Air Plane:  How Ideas Gave Us Wings (2008), suggests that the construction of heavier-then-air craft may owe a debt of gratitude to the insect world, and specifically the dragonfly.  Frankly, I think Spenser is reaching for it, but, oh, why not?  The example Spenser provides is that of the monocoque (one-shell) construction that, in the early 1900s, helped make some airplanes lighter and sleeker.  In essence, under this approach, the exterior shell (read exoskeleton, like that of an insect) of the fuselage bears the stresses of flying, eliminating the need for internal supports.  This mode of construction works only for smaller planes, while semi-monocoque construction, where the load bearing is shared by the outer shell and some internal supports, remains in use for today’s large airliners.  Spenser writes,
. . . it’s the dragonfly with its long body and prominent wings that serves as nature’s poster child for monocoque construction.  (ebook version, p. 70)
Now that I’ve obfuscated the transition, I’ll turn to flight by humans.  Yes, this year’s the 50th anniversary of the Apollo 11 flight and the first walk on the Moon.  I thoroughly enjoyed the documentary film Apollo 11 now streaming on Hulu which offers incredible contemporary footage of the trip.  (Complete with the jarring appearance of Vice President Spiro Agnew at the launch and the stilted words of congratulations later from his boss.)  But, for me, all the hoopla this year about Apollo 11 is only a relatively small part of what makes this year important in terms of flight.

There’s a signal aviation event that needs to be celebrated this year:  the first non-stop flight across the Atlantic a century ago in 1919.  And, no, that’s not Charles Lindbergh’s thing (which was the first solo flight across the Atlantic on May 21-22, 1927).  Rather, what should be memorialized this year is the flight on June 14-15, 1919, by British aviators John Alcock and Arthur Whitten Brown in their Vickers Vimy biplane.  They covered the 1,880 miles across the Atlantic from Newfoundland to Ireland in somewhat more than 16 straight hours.  Brendan Lynch has written an authoritative account of that journey in Yesterday We Were in America:  Alcock and Brown, First to Fly The Atlantic Non-Stop (2019).  Well worth reading.  The Vickers Vimy with Alcock at the controls and Brown navigating is seen below as it left St. John’s, Newfoundland, on June 14.

(Wikimedia Commons reports this image to be in the public domain.)

The two were international celebrities after they landed in Ireland, though, sadly, Alcock was to enjoy that status only briefly, dying in a plane crash in December of that year.

Admittedly, the Vickers Vimy was no sleek beauty, no obviously aerodynamic masterpiece, no poetry in motion.  Yet just as the dragonfly’s old-school wing construction was (and remains) effective, so, too, did the bi-winged/box-kite structure of this plane enable it to take a giant leap in our aerial adventure.

Wednesday, July 31, 2019

An "Aberrant" Path for Sand Dollars

Until now, I would have said, without qualification, that the shells or tests of sand dollars are things of subtle beauty.  In a moment of weakness, I might even be tempted to ascribe some aesthetic purpose to the artistry of the five-pronged stars etched delicately on the obverse of the tests, or to their wonderfully symmetrical disk-like shape.  We are, indeed, attracted to the symmetrical.

But certain fossils recently added to my collection challenge my overall assessment of the charm and beauty of sand dollars.

The echinoderm order Clypeasteroida includes the sand dollar whose rigid test is made up of interlocking plates.  (Of interest, this order’s name comes from the Latin clypeus = shield or medallion, and aster = star.)  The sand dollar, whose calcium carbonate plates readily fossilize, is a relatively recent arrival on the world scene.  The University of California Museum of Paleontology notes that echinoids (which include sea urchins, among other taxa) first appear in the late Ordovician (458 to 444 million years ago), but that the sand dollar shows up only in the Paleocene (66 to 56 million years ago). (Introduction of the Echinoidea, UMCP.)

At a recent gem and mineral show, I came upon a small container sporting the label: “fossil sand dollars.”  At $1 apiece, these small fossils were hard to resist, so I purchased a few.  As seen in the example below, these fossils are quite striking with a shape certainly unlike that of any sand dollar I’ve seen.  (Clearly, my specimens had suffered some breakage.)  Unusual they are, beautiful they are not.

These particular specimens belong to the Rotulidae family whose members exhibit digit-like projections of the test (I refer to them as “digits” below, though they clearly are not fingers).  The Rotulidae first enter the sand dollar family during the Miocene (23 to 5 million years ago).  I have concluded these specimens belong to the genus Heliophora which, according to The Echinoid Directory of the Natural History Museum in London, includes a single species, H. orbicularis.  I am particularly persuaded in my identification by those robust protrusions of the test.  As the NHM puts it for this species, “Posterior of test strongly digitate.”  The NHM also notes that this taxon is first found in the fossil record in the late Pliocene (5 to 3 million years ago) and that it is an extant species found on the west coast of Africa.  So, my specific fossils are, in the scheme of things, remnants of very recent additions to the planet’s fauna.

On my H. orbicularis and on Rotulidae, in general, the digits appear at the posterior of the test.  The dorsal side of the test is somewhat raised (meaning the test is not flat) and shows the star etching, while the ventral or oral side is flat and has two holes in it.  The hole in the center of the oral side is the peristome opening which serves the animal’s mouth, while the second hole, nearer the digits, is the periproct opening which serves the anus.  Though the periproct’s location is variable among sand dollar species, in many it is in the rim of the test.  That’s not the case here, based on my understanding of the Heliophora.

The test’s digits need some explaining.  From my reading to date, I’m not sure there’s a scientific consensus about them.  Two aspects of how sand dollars live (lived) are relevant here.  First, sand dollars are filter feeders, with features (including many spines covering the test; these spines are not preserved in fossils) that act to channel microorganisms such as diatoms into its mouth.  The movement of food occurs not just on the oral side of the test, but also on the dorsal side.  The raised dorsal side with grooves that run down it help to channel food toward the oral side of the organism.

Second, sand dollars live on or in sedimentary beds in moving water.  This introduces consideration of how the shape of the test responds to the hydrodynamic forces of moving water.

I assume that, evolutionarily, there has been an interplay between the demands of securing food and those of "sedimentary" living and coping with moving water.  For the Rotulidae with their test digits, paleontologist Adolf Seilacher’s discussion in Morphodynamics (2015) is relevant.  In this volume, he posited that “lunular notches” in sand dollars – the perforations through the test found in several types of sand dollars; this term includes the digits of the Rotulidae – arose for a constellation of different reasons.  These include aid for digging by allowing sand to move more easily from the oral side to the dorsal side; stability by reducing the lift effect of water moving past the test; and feeding by facilitating the movement of food from the dorsal to the oral side.

In an earlier article, Seilacher noted a possible explanation for the concentration of lunular notches or digits in the posterior edge of the Rotulidae.  Members of this family may increase the effectiveness of these digits for filter feeding by positioning themselves in an upright position in the sediment with the digits exposed to the water currents.  (Constructional Morphology of Sand Dollars, Paleobiology, Volume 5, Number 3, 1979.)

I am struck by how the Rotulidae, those sand dollars with digits, break the connection with the common name for this kind of organism, a name which refers to the test’s similarity in shape to a silver or gold dollar coin.  If the only “sand dollars” we knew were Rotulidae, I doubt they’d have that common name.  Indeed, the H. orbicularis in particular hardly looks like a coin and bears little resemblance to the common names given this group of organisms by other cultures and in other languages.  For instance, H. orbicularis certainly doesn’t bring to mind a cookie, a frequent reference point elsewhere in the world (e.g., sea cookie in New Zealand, galleta de mar in Spanish).  Nor does it evoke a flower (e.g., sea pansy in South Africa).  Yet, the French, it would seem, might have no problem with the unusual shapes of the Rotulidae because, in French, a sand dollar is called (I think) oursin plat, meaning flat sea urchin, a common name which sacrifices metaphor for broadly accurate, though boring, descriptors.

In the end, I fear the H. orbicularis and the other Rotulidae leave me cold.  Their digits make them interesting but also render them much less attractive.  Perhaps the most interesting aspect of the digits is they appear in the Rotulidae which enter the fossil record somewhat later than sand dollars in general and are limited to just three genera.  This, it would appear, is a new evolutionary path for sand dollars, but, at least so far, one that remains very much a minor, restricted “experiment” among the Clypeasteroida.  May it remain so.

Friday, June 14, 2019

David H. Koch Hall of Fossils - Deep Time
~ Come for the Dinosaurs, Absorb the Lessons

On June 8, 2019, after five years of work, $125 million, and, I’m certain, myriad headaches, the Smithsonian’s National Museum of Natural History opened its completely renovated fossil hall, the David H. Koch Hall of Fossils – Deep Time.  This post describes primarily what caught my eye on my first visit to this remarkable hall.  Given that it houses over 700 fossils and presents some 75,000 words on its signage, I clearly missed a great deal and return visits are in order.  At the outset, I would note that, for all intents and purposes, this is a new hall and that’s how I’ll refer to it below.

The prior incarnation of a Smithsonian fossil hall enveloped visitors in darkness that seemed to emanate from the crowded displays, the gloomy worn carpeting, the faint-hearted lighting, and even the outdated science that was referenced in the skeleton poses and the signage.  No natural light, no windows.

This newest hall greets the visitor with grace, space, and, above all (quite literally) light.  (Dear visitors, please embrace these attributes wholeheartedly.)  The picture below – a panorama shot of a  Diplodocus skeleton stretching nearly 90 feet from the tiny tip of its tail (curving off to the left) to its undersized head at the end of a wonderfully long neck – shows some of the new hall in much of its airy glory.

That’s where I have to begin, with the dinosaurs, because that’s where most who come to this hall will naturally first gravitate.  And the child in most of us will find irresistible the tableau in the center of the hall’s long room where a Tyrannosaurus rex and a Triceratops horridus portray a scene that may well mirror many that actually occurred some 66 million or more years ago.

Of note, the skulls of both skeletons shown above are casts because the actual skeletons (housed elsewhere in the museum) would have weighed too much to be posed in such close proximity with each other.  This is described in an article and illustrated map of the new hall that appeared in the Washington Post (Bonnie Berkowitz and Aaron Steckelberg, A New Old Home for the Nation’s Dinosaurs, June 2, 2019).  This is a highly informative piece on the new hall.  Well worth exploring.

Labels throughout the hall clearly identify what’s a cast and what’s not.  Material that fills in incomplete specimens are a different shade allowing the sharp eyed to distinguish real fossil from manufactured material.  I have to say that some of these differences in shading are too subtle for my eyes.

Back to the tableau of a teenage (it is assumed) T. rex beginning to munch on a T. horridus.  It fails to answer a question debated among paleontologists.  Was T. rex a predator or a scavenger?  The display is agnostic on this, though, in all likelihood, T. rex went both ways.  (Hear National Museum of Natural History’s director, Kirk Johnson, discuss this aspect of the T. rex on the NPR show 1A with Joshua Johnson (episode aired on June 11, 2019).  In this episode, Kirk Johnson waxes enthusiastic about many features of the new hall.)

Among other dinosaurs found here is this Camarasaurus skeleton positioned near the Diplodocus.

The Camarasaurus picture highlights one distinguishing feature of the new hall:  there’s no effort to fill spaces with recreated, lifelike foliage from the diverse time periods.  Rather, the vegetation representations are minimalist.  The hall does allow visitors to see the ecosystems of such worlds, depicting them in little “diorama” stands scattered throughout the hall.

Here’s a close-up of the diorama of a grassland scene some 19 million years ago, reconstructed on the basis of fossils found in the Harrison Formation, Nebraska.

How is this new hall organized?  The designers want visitors to enter from the museum's rotunda and, so they are to begin with recent history, not deep time.  Visitors are greeted by bronze statues of a human family being stalked by a saber-toothed tiger.  The former recognizable, the latter striking but still mostly familiar.  Walking from the entrance down the length of the main long gallery, visitors at first move somewhat slowly back in time, only hundreds of thousands of years in those initial steps, but then rather quickly millions of years go by until, angling off to the left from this first gallery, visitors come to the initial emergence of life on the planet.  This organization forces a rethinking of time as, in the process of walking through the exhibits, the familiar or somewhat familiar is replaced by the faintly familiar which in turn is replaced by the truly different, alien even.  Deep time, for sure.

There is a spiral motif that marks some of the hall’s signage which not only represents how Earth’s history reaches far, very far back in time, but also speaks to the connections among all things.  The past is, indeed, prologue.  No “special creations” here.  One such spiral sits high over the entrance to the hall accompanied by a quotation from Charles Darwin’s On The Origin of Species.  That quotation marks one of the recurrent themes that is traced throughout the hall’s displays – the history of life on this planet cannot be understood without a recognition of the fundamental role that evolution played and is still playing.

No shying away in this hall from evolution.  Indeed, a statue of a young Charles Darwin sits near the center of the hall with a Galapagos finch (?) perched on his shoulder.

This message about evolution’s central role in life on Earth is unavoidable as one’s path in the hall moves from the present into deep time.  Among the many exhibits and signage positing and elaborating on this theme, is a large sign featuring Smithsonian paleobiologist Gene Hunt.  An extensive set of quotations from him begins, “Species evolve by natural selection to meet the challenges of the world.”  Accompanying this is a fascinating (at least it was to me) display of two arrays of specimens of the bivalve mollusc Spondylus, commonly, though erroneously, referred to as “spiny oysters.”  The array on the left shows eight Spondylus specimens from a single species that lived in Florida some three million years ago.  Back then specimens of this species exhibited some, relatively marginal variations.  But, as the display notes, “Over time, variations like these can become the building blocks of new species.”  The eight Spondylus specimens on the right are from different species of this genus living in oceans today.

That evolution has had to contend with several major extinction events in deep time is unquestionably also a central element in the hall’s lesson on evolution.  One of the most striking ways this is conveyed comes when one gets back to the end-Permian extinction.  Here is a close-up of the key part of a graphic showing the wealth of diversity among plants and animals that marked the Permian in general (at the left of the event), but which was abruptly curtailed:
Massive volcanic eruptions 252 million years ago released gases that dramatically altered the climate, causing extinctions that rippled through food webs and devastated animal communities.

Emerging from that extinction event, life on Earth was diminished with a tremendous loss of diversity.

Embedded in the text of that sign is another fundamental message of the new hall that is repeated many, many times – Earth’s climate changed frequently in deep time and such changes had fundamental consequences for life on this planet.  Yet, as central as this message is to an understanding of how life as we now know it came to be (yes, the living are all connected in this great spiral of time), what impressed me perhaps most forcefully about the new hall was the way the content of that message is framed for visitors when they begin their journey.  Here is one way that message is delivered early in that journey.

"And humans are the cause."

And another:

One early kiosk loops a video discussing what can be learned about climate change over the past several hundred thousand years by studying ice cores.

Toward the very end of the short video, after it shows the strong correlation discovered between changes in the concentration of carbon dioxide and changes in the Earth’s temperature (more carbon dioxide, higher temperatures), the voice-over narrator says this:
Today CO2 is skyrocketing higher than any time in the past 800,000 years as we burn fossil fuels and cut down forests.  This time, humans are the reason Earth’s temperatures are rising.
Human’s lethal touch on life on Earth is felt in other ways as this display asserts.

To me, that’s the most amazing aspect of the new fossil hall – its robust assertion, clearly backed by science, that today’s climate change has human activities as its root cause and that it poses an existential threat.

Why is this amazing?  Because it shows that a bright line was drawn between David H. Koch, the core financial donor to the remaking of the fossil hall, and the content of the new hall.  David and his brother, Charles, head a multinational corporate empire founded by their father which, among other things, owns oil refineries and pipelines.  Writer Jane Mayer profiled the Koch brothers in a fascinating and detailed article in 2010 that ran in The New Yorker (Covert Operations, August 30, 2010).  In it, Mayer wrote:
The Kochs are longtime libertarians who believe in drastically lower personal and corporate taxes, minimal social services for the needy, and much less oversight of industry—especially environmental regulation.
Their attitude toward climate change?  As quoted by Mayer, a 2010 Koch Industries newsletter asserted that "fluctuations in the earth’s climate predate humanity . . . .  Since we can’t control Mother Nature, let’s figure out how to get along with her changes.”

That's why I think it quite striking that the new hall teaches its lesson about today’s climate change so strongly (stridently even), despite the beliefs of that donor.

I fear I've given the richness of the new hall short shrift because all I've highlighted has been the dinosaurs and the interwoven messages that I hope all visitors absorb.  There are hundreds of fossils on display, most much smaller than those awesome Mesozoic creatures.  I will close with a picture of what is one of the jewels of this new hall (I agree with director Kirk Johnson on this).  The piece of matrix pictured below comes from the Green River Formation (Wyoming) and features the 52-million-year-old, intact, incredibly beautiful skeleton of a tiny early horse, Protorohippus venticolum.  This is the most complete skeleton of this early horse species found to date.  The preserved detail is breath taking.  Given the fossil impressions of several fish in this matrix, evidently this horse died at a lake’s edge, floated out on the water for some distance, and then sank to the bottom.

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