Fossil Hunt Diary

The format and illustrations of this post were inspired by “Metropolitan Diary,” a feature of the New York Times that runs each Sunday.  I love this weekly column which, over the years, has spoken to me in myriad ways, often prompting laughter, and, on occasion, tears.  It offers five brief, true stories written by Times readers about life in New York City.  These miniature essays, recounting some specific experience, capture the urban existence in tiny prose gems.  The five stories in this past Sunday’s (December 25, 2022) column, were selected by readers as the best of 2022.  They are quite wonderful.  Still, I was disappointed that one of my favorites from 2022, written by Sharyn Wolf and titled Rock, Rock, Rock (included in the December 18, 2022 column), failed to make the cut.  That one begins:

“Rock, rock, rock,” I heard a voice repeating.  “Rock, rock, rock”

I was walking up a trail into the ramble in Central Park when I came upon the voice’s owner:  a tall, slender man with a twist of silver hair over one eye.

I waited, not wanting to interrupt whatever it was that he was doing.

“Rock, rock, rock,” he said again in a monotone.  “Rock, rock, rock.”

The explanation that Wolf provides in the ensuing three short paragraphs is unexpected and delightfully funny.

These wee tales are hard to resist and their appeal has been enhanced over the past five years with deceptively simple drawings by artist Agnes Lee.  These appealing illustrations have a timeless quality to them.  Lee has written about her arrival in New York City and the process she follows preparing these drawings.  Though she is now leaving the city for the West Coast, her artwork will continue to grace “Metropolitan Diary.”

The story which follows is somewhat modeled on the Times column; it includes two of my illustrations influenced by Agnes Lee's.

Some further context is needed.  The setting is Purse State Park, a tree-lined Paleocene site on the Maryland shore of the Potomac River about which I’ve previously posted.  The man named Mel featured in this account was a committed, consummate fossil collector who was a mainstay in a fossil club to which I still belong.  A wonderful person, he has since passed away.

Here then is my fossil hunt diary entry:

Several days after joining a fossil club and attending my first meeting, I was hunting fossils at Purse State Park, wandering somewhat aimlessly and unproductively along the deserted shoreline.  I struggled to climb over, or around, the fallen trees lying in the water.

I had no idea what I was doing.

Suddenly, though, I spotted something in the water at my feet.  I reached down and picked it up:  a beautiful fossil shark tooth.  What kind was it?  As I stood there puzzling over my find, a voice startled me.

“Hey, what do you have there?”

I turned around and there was Mel, whom I'd met at the club meeting.

I extended my hand to show him the tooth.

“Otodus obliquus.  Nice one,” he said.

It was at that point that I realized what a truly amazing organization this club is:  I go out into the field, find something I'm not sure about, and a club member immediately appears to give me the definitive ID!

The Color of November

 In the waning days of November, I cleared out a small area in my front yard.  Only then did I consider whether shrubs might be planted so close to the year’s end.  I thought that Joe Eck and Wayne Winterrowd might advise me, so I consulted their lyrical A Year at North Hill:  Four Seasons in a Vermont Garden (1996).  Landscapers Eck and Winterrowd were introduced in a post on asters nearly a decade ago.  In their chapter devoted to November, I found no inspiration about what to plant, possibly because that far up in the northern latitudes planting was now out of the question.  But I was inspired by Eck and Winterrowd’s characterization of November which prompted this post; I surround myself with a group of wonderful nature writers (and one cartoonist who is an expert on human nature) and see how their views of November might inform my own.  (Note:  Fossils don’t make an appearance in this post.)

I’ve come to appreciate that, here in the mid-Atlantic and further north, November is a special month, a transition month like no other in the calendar year.  The contrast between what came before and what the latter days of November offer is unique; we move from harvesting summer’s bounty and basking in October’s dramatic colors (the wash of reds, yellows, purples, and oranges in the deciduous trees as they mark the passing of their season of growth) to a time of hunkering down, living more in darkness than light, and often mourning an apparent loss of color in the landscape.  The change is quite abrupt and, for many, a depressing taste of a winter to come when a look back, around, and forward offers no relief.  Grayness has arrived.

That is, precisely, what Eck and Winterrowd write of November:

We could never say about this somber month that it is our favorite in the garden.  As the year winds down to its close, gray days occur with greater and greater frequency - not cloudy and not sunny, but simply gray.  Gray is also the predominant color of the garden and surrounding woods.  Most of the fiery splendor of October has fallen, revealing the great boles of trees and tanged architecture of deciduous shrubs, now an endless play on one monochromatic color.  (p. 125.)

So, for these Vermont gardeners, November equals gray.  (Though I must admit that perhaps in my area, hundreds of miles south of North Hill, late November may not be quite as gloomy.  That will emerge in a bit.)

New Yorker cartoonist Roz Chast agrees with Eck and Winterrowd.  Her cartoon titled November in the November 21, 2022, issue of the magazine features three shell-shocked individuals, typical denizens of her cartoons.  They are standing on a city sidewalk, mouths agape, hair in frizzy explosion, and arms nervously shaking.  They are clothed in well-worn jackets clearly guarding against the cold, and the scene around them is awash in gray.

The first person complains:  “It’s only 4:15, but it’s PITCH DARK!”

The second warns:  "Something is seriously amiss."

The third laments:  "It's the end of the world."

Now that is a truly dire, truly gray view of November, one brought on, of course, by the loss of daylight saving time.  But this month, even without that time change, would still be a period of shortening days and lengthening nights.  Darkness encroaching steadily.

Yet it’s not only this transformation from a time of abundance, light, and color to one of grayness that November effects. The month literally provides a degree of profound clarity to our landscape.  Writer Verlyn Klinkenborg, from the vantage point of his Vermont farm, captures that truth when he describes November as “this bare month.”  That he also shares my sense of the transition we’ve undergone is made plain when he adds:  “October’s memory seems a little lurid from the perspective of mid-November.”  (The Rural Life:  A Private Month, New York Times, November 19, 2006.)

But this is not the apocalypse, no matter what the Chast cartoon characters might think.  That clarity offers a chance to consider changes to your landscape.  Eck and Winterrowd write that November has days inviting one outside in the light of a “lowering sun,” “to evaluate plantings that show their structures better for having been stripped, and to make ambitious plans for the spring – what to move and what to order.”  (p. 126, 127.)

The opportunity to view your landscape, or just your garden, as a whole and consider its immediate and long-term future is an integral feature of November, something which triggers very different responses.  Planning for action in the spring helps with the transition from fall to winter, and seed catalogues are a tool of choice for this.  This is quite passive compared to a more robust embracing of that opportunity to chart the future of the land.  Consider what the visionary conservationist and ecologist, Aldo Leopold writes in his seminal book, A Sand County Almanac (1949), about this eleventh month of the year as it plays out on his 80-acre farm in the sand country of central Wisconsin:

November is, for many reasons, the month for the axe.  (p. 68.)

Yes, he, too, sees November as a month of opportunity with a focus on the trees that, with the loss of their leaves, stand in sharp relief, making it clear where their branches intersect and what the arc of their growth will be.  He writes, "Without this clear view of treetops, one cannot be sure which tree, if any needs felling for the good of the land."  (p. 68.)  Some will obstruct others, some will ultimately destroy others.  Given the finality of taking an axe to a tree, Leopold lays out at length how he passes sentence, exploring the various biases that may influence his decisions. Ultimately, he concludes, "The wielder of an axe has as many biases are there are species of trees on his farm."  (p. 70)  Thus, November to such a wielder of the axe in the landscape is a month of planning, foresight, and being, oh, so, deliberate in this action.

November also offers an invitation for a different kind of contemplation, for taking a moment from the rush of living to look broadly and closely at the natural world around us, not because we want to change things, but because we move beyond the boundaries of what we might control.  As he writes in A Year in the Maine Woods (1994), biologist and naturalist Bernd Heinrich deems November a month for stalking deer.  Yet, though he journeys through the month armed with a rifle, rarely is a shot fired, rather he spends his time hiking through the woods on and near his old Maine homestead and farm, or sitting high up in a tree.  All the while he’s observing the scene around him, registering the activities of the animals, particularly the birds (his books on birds are wonderful), studying the trees and plants that grace the woods.

My sense is that, by taking the opportunity in November for a close observation of nature, there comes a leavening of the Chastian dread that accompanies the month’s plunge into grayness.  The relief can be subtle, hardly dispelling the gloom, but still there nevertheless.  Heinrich captures it well.

From my perch in a tree, and walks to and from it I see the predominant gray and white tree trunks, and the kaleidoscopic pattern of browns from their fallen leaves.  It is a rare event indeed to see a deer on a deer watch, but until I do I enjoy seeing the woods – particularly the stunning display of mosses and lichens that are now an open book.  Before, when the canopy was green with leaves, and the ground was covered with herbs and small seedlings, these mosses did not stand out.  Now they shine with luminescent brilliance.  (p. 136.)

The month can have surprising color.  Some of that is reflected in Dorothy Wordsworth’s journals.  She, the sister and an inspiration for poet William Wordsworth, is a sensitive observer of nature in the Lake District of England.  Her journals are fascinating, mixing accounts of the mundane – who’s visiting whom (poet Samuel Coleridge was a close friend), and who’s ill or recovering – with spellbinding passages describing the natural scene around her.  (Journals of Dorothy Wordsworth, 1971.)

Hers is a gentle view of nature, a positive, upbeat one.  At this time of the year, colors are there, though often quite muted.  I like the entry for Sunday, November 15, 1801.  The image she creates of a landscape seeming at rest is delightful (as are the place names).

I walked in the morning to Churnmilk Force nearly, and went upon Heifer crags.  The valley of its winter yellow, but the bed of the brook still in some places almost shaded with leaves – the oaks brown in general but one that might be almost called green – the whole prospect was very soft and the distant view down the vale very impressive, a long vale down to Ambleside – the hills at Ambleside in mist and sunshine – all else grey.  (p. 58.)

There’s the grayness but also some counterbalance to it.

I am taken by what she writes on Sunday, October 23, 1802, though it’s not an entry for November.  I think it merits quoting because she uses a word that so perfectly captures what is happening at this time of year.

It is a breathless grey day that leaves the golden woods of autumn quiet in their own tranquillity, stately and beautiful in their decaying, the lake is a perfect mirror.  (p. 162.)

Decaying, perhaps that’s the fundamental dynamic at work in how one might come to view the month.  This process starts in October, signaled by the burst of colors from the tree leaves, and continues deeply into November.  I wonder if it may be less the dullness of the encroaching grayness that worries us, but, rather, the subconscious recognition that this is a time of decay, things dropping away, breaking apart.

We are conditioned to view the month as monochromatic but, even when writers such as Wordsworth note the grayness, they punctuate their descriptions with notes of other hues.  I do think that, in this month, there is brightness and richness, if only you, like Heinrich, are open to it.  So, I went in search and found wonderfully sudden splashes of color adorning some of the paths down which I wandered.  Particularly striking are deep, robust blood reds.  Consider these seed clusters of sumacs (horn or smooth, I don’t know which) that I came upon in Brookside Gardens (a 54-acre site in the public park system of Montgomery County, Maryland):

Or the winterberry bushes outlined with their berries (also at Brookside):

Or the Christmassy palette of the St. John’s Wort in my own garden, capped by plump red berries:

Though November marks a fundamental transition from abundant growth to a time of decay, it offers more than just despairing grays.  It’s also a month of clarity, offering the chance of taking stock and looking forward.  It invites a closer look at the landscape and the chance to be moved by unexpected bursts of color.  There’s certainly enough here to keep one moving forward.

On A Piece of Jurassic Basalt

 

Sliding down upon the slide

Seems like it never ends

When we get to the other side

Maybe then we'll make amends

It's the end of time

The end of time

Can you feel it?

Can you feel it?

It's the end of the line

It's the end of time

Lindsey Buckingham

End of Time on the album Seeds We Sow (2011)

Is there a limit to how much significance a person can ascribe to an inanimate object?  I’m certainly guilty of overthinking nearly everything and may be particularly guilty of that when it comes to the small chunk of nearly 200-million-year-old basalt, collected from a site in Hartford, Connecticut, which sits on a bookshelf next to my desk.  I see this rock as a symbol and a warning.

I collected it and a few other pieces of basalt about a decade ago, and wrote about them in a post prompted by a visit to my mother-in-law whose retirement community was seated on top of a basalt ridge.  That post placed the basalt somewhat in context but, in retrospect, I did not do it justice, missing much of the meaning.  This post paints a fuller and necessarily much darker picture.

The solidity, dullness, and quiescence of this rock belie its explosive and destructive history.  I believe this is Jurassic Holyoke basalt, part of “one of the world’s largest basalt flows” which created a lava lake that took a century to cool.  (Philpotts, 2012; Philpotts, 2010.  Full citations are provided in the References section at the end of this post.)  Holyoke basalt is dated to an estimated 199.3 million years ago (plus or minus 0.6 million years), meaning it formed just about at, or shortly after, the beginning of the Jurassic Period (201.3 to 145.0 million years ago).  (Marzoli, 2011, Figure 2.)  This was essentially just a geological minute after the end of the Triassic Period (251.902 to 201.3 million years ago) which went out with a mass extinction that consumed some three-fourths of animal life on Earth.  So, though I cannot directly implicate this rock in that extinction event, one of the big five massive ones upon which there is general scientific agreement, I think it’s part and parcel of a series of volcanic events that straddled the boundary between the Triassic and Jurassic periods and which did the deed.

Basalt, an extrusive igneous rock, is formed from magma flowing onto the planet’s surface as lava from volcanoes or volcanic fissures.  Despite being the most prevalent igneous rock, nearly all of it is out of sight, constituting the central component of ocean floors.  Most telling for this post, its volcanic origins link it to some of the most extensive animal extinctions on Earth.

Mass extinctions hold a morbid fascination; they’re car wrecks I cannot turn away from, largely because I see ourselves in one.  We humans have initiated our own global wreck from which none of us will escape unscathed.  I don’t think that’s a too pessimistic or too alarmist point of view.  Whether we’re in the beginning of the sixth mass extinction animal life has experienced on this planet or not may be mostly a matter of semantics.  Even if we’re not, something wicked this way comes and, indeed, has entered the building.  (There are those who argue that, until we’ve actually passed the tipping point and there’s no way of turning back, we’re not in a mass extinction.  Something of a distinction without a difference, I think.)

For several of the planet’s previous mass extinctions, it would seem that massive amounts of basalt are compelling clues as to a probable cause.  As Peter Brannen, in his The Ends of the World, writes

The three biggest mass extinctions in the past 300 million years are all associated with giant floods of lava on a continental scale – the sorts of eruptions that beggar the imagination. . . .  In these rare eruptive cataclysms the atmosphere becomes supercharged with volcanic carbon dioxide, and during the worst mass extinctions of all time [the End-Permian mass extinction], the planet was rendered a hellish, rotting sepulcher, with hot acidifying oceans starved of oxygen.  (Brannen, p. 4.)

Not a pretty or encouraging picture, particularly given what we’re doing right now - pouring massive amounts of carbon dioxide and other greenhouse gases into the atmosphere.  (Note that the 300-million-year period Brannen mentions here covers the last three mass extinctions:  End-Permian, End-Triassic, and End-Cretaceous.  The inclusion of the last might cause some agita for those who attribute that extinction solely to a collision of a bolide with Earth.  Brannen is quite interesting on that score.)

Over the years, I’ve read several popular books on mass extinctions and Brannen’s is certainly an excellent treatment of the subject.  How could it not be?  The superb science writer and paleontologist Steve Brusatte wrote recently that this book is “the best pop-science book on mass extinctions,” and, he goes on to assert, Brannen “is one of the finest science writers working today, and his earth science writing is on par with my favorite all-time geologizing author, John McPhee.”  (Brusatte, 2022, p. 145.)

Basalt formations figure prominently in Brannen’s account of the End-Triassic mass extinction for good reason.  Not only are they signs of the volcanic havoc that occurred at the time, but they are very accessible in North America.  He recounts his exploration of the Palisades basalt cliffs in New Jersey with the eminent paleontologist Paul Olsen and, so, sees up close and personal “the continental flood basalt that wiped out the Triassic world.”  (Brannen, 2017, p. 153.)

What’s the relationship of my bit of basalt to the events that doomed the Triassic world?  The following two maps orient the formation from which I collected this basalt.  Its history also helps to place it in proper context.  The first map is a small portion of the 1985 Bedrock Geological Map of Connecticut  prepared by the Connecticut Geological and Natural History Survey to which I’ve added an arrow (located in a slightly different place than it was in my earlier post) pointing to the location of where my basalt was collected (on the edge of Cedar Mountain).  The reddish orange area on the map (labeled Jho) marks Jurassic Holyoke basalt.  As already noted, this basalt is dated just after the end of the Triassic.

This second map is from Trap Rock Ridges of Connecticut and provides a close-up look at the igneous features of Connecticut’s Central Valley (part of the Hartford Basin).  (Lewis, 2013, Figure 5.)  The little brownish line numbered 6 is Cedar Mountain.

In the Trap Rock Ridges of Connecticut, geologist Ralph S. Lewis’ chapter provides a succinct and accessible description of the geological story behind these ridges, nicely inserting my piece of basalt into part of the larger geological picture.  (Lewis, 2013.)  What follows is my very brief summary of the aspects of the story he tells relevant to this post.

The original tectonic forces moving east and west that pushed Eurasia, Africa, and the Americas together, creating Pangea, generated mountain ranges that ran (and run) north/south.  As the super continent began to break apart during the Triassic, those forces reversed course, pulling the land apart, creating rifts that paralleled the mountain ranges.  In Connecticut’s Central Valley, the developing rift valley acquired sediment from the weathering and eroding metamorphic rock on its eastern and western borders.  As expansion continued, magma rose through faults and fractures, intruding into, or extruding over top of, the sedimentary rock in the rift valley.  Periods of sedimentary deposit were interspersed with three major extrusive lava flows:  Talcott Basalt, Holyoke Basalt, and Hampden Basalt.  Of these, the Holyoke Basalt was the largest.

Let me expand on Lewis and focus on a critical part of the story (critical, at least, to this post).  The Connecticut Central Valley lava flows were an extended part of the broader, protracted volcanic event that marked the rending of Pangea:  the creation of the Central Atlantic Magmatic Province (CAMP).  CAMP is a massive area composed of basaltic magmas that flowed over a 10 million square kilometer area of Pangea.  (Marzoli, 2018, p. 91, 101.)  The peak CAMP event straddled the boundary between the Triassic and Jurassic.  As a result, CAMP is directly implicated in the End-Triassic mass extinction.  As Marzoli and colleagues write, “There is now general consensus in the scientific community that volcanic gases released by CAMP likely were the trigger mechanisms of the end-Triassic mass extinction and accompanying carbon cycle disruption.”  (Marzoli, 2018, p. 114, cited sources omitted.)

Significantly, though the lava flows creating CAMP were concentrated in a roughly 1-million-year period (at the end of the Triassic), the geologic processes involved probably lasted for a full 10 million years.  (Marzoli, 2018, p. 101.)  Thus, though my basalt cannot be accused of killing the Triassic, it is, at least, an accessory after the fact.

I keep coming back to the real smoking gun in this and other mass extinctions, and it’s not the physical damage wrought by these lava flows (bad as it was) that bears the responsibility for ending worlds.  Rather, the lethal weapon was “the volcanic gases released during the tectonic mayhem.”  (Brannen, 2017, p. 157.)  And, foremost among those gases?  Carbon dioxide.  Seems unsettlingly familiar, given what we’re doing to our current atmosphere.  As Brannen observes, of the death of the Triassic world:

Though it wasn’t nearly as extreme as the End-Permian, the End-Triassic mass extinction seems to have been a sort of Great Dying Jr., with huge injections of carbon into the atmosphere from volcanoes and a lethal super-greenhouse as the result.  But the End-Triassic mass extinction might also serve as a gruesome template of sorts for our next few centuries.  (Brannen, 2017, p. 159, emphasis added.)

For me, that sobering thought infuses my basalt with its fundamental meaning.  What a hellish world had come into being as this basalt was formed, a kind of world we seem to be inexorably recreating and bequeathing to our children’s children.

References

Brannen, Peter, The Ends of the World:  Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions, 2017.

Brusatte, Steve.  The Rise and Reign of the Mammals:  A New History, From the Shadow of the Dinosaurs to Us, 2022.

Lewis, Ralph S., Geology of the Trap Rock Ridges, a chapter in Penelope C. Sharp, et al., Bulletin No. 41:  Trap Rock Ridges of Connecticut:  Natural History and Land Use, Bulletins, Connecticut College Arboretum, 2013.

Marzoli, Andrea et al., Timing and Duration of the Central Atlantic Magmatic Province in the Newark and Culpeper Basins, Eastern U.S.A., Lithos, 2011.

Marzoli, Andrea et al., The Central Atlantic Magmatic Province (CAMP):  A Review, chapter 4 in Tanner, Lawrence H., editor, The Late Triassic World:  Earth in a Time of Transition, 2018.

Philpotts, Anthony R., The Holyoke Basalt, Its Source and Differentiation in a Thick Flood-Basalt Flow, Abstract, Annual Meeting of the Northeastern Section of The Geological Society of America, March 2012.

Philpotts, Anthony R., The Holyoke Basalt at the Tilcon Traprock Quarry, Chapter II of  Peter M. LeTourneau and Margaret A. Thomas, editors, Traprocks, Tracks, and Brownstone:  The Geology Paleontology, and History of World-Class Sites in the Connecticut Valley,, The Geological Society of Connecticut , Field Trip Guide Book No. 1, 2010.

Misperception: Women and Science

Lab Girl (2016), paleobiologist Hope Jahren’s vibrant and compelling memoir chronicles the academic and professional barriers that can impede a woman navigating a career in the sciences.  In the process, she brings me face to face with a telling misperception of mine.  (More on that later.)

Jahren’s father taught science and ran a science laboratory at a community college in a small Minnesota town.  Her experiences as a child finding pleasure and solace in her father’s lab provided fertile ground for her desire to study science.  It’s a course she’s pursued successfully, but one, she notes, that was largely denied her mother whose initial college stay was brought short because, “in 1951, the university experience was designed for men, usually men with money, or at the very least men who had job options outside of being some family’s live-in nanny.”  (p. 15)  Hope Jahren has earned an undergraduate degree in geology at the University of Minnesota, and a Ph.D. from the University of California, Berkeley.  She taught at Georgia Tech, Johns Hopkins University, and the University of Hawaii.  At each of those institutions, she established and ran a laboratory.  She is currently a professor at the University of Oslo.

Lab Girl moves on two related tracks, one describing Jahren’s life in science, the other introducing the reader to the life of plants, particularly trees.  At one point, she characterizes her scientific focus as figuring out “what it’s like to be a plant” (p. 76); taken together, the chapters devoted to plants serve as a compelling introduction to that perspective.  Jahren makes it abundantly clear that plants in fact do have lives, and she salutes the miracles they perform daily – creating sugar, drawing carbon dioxide from the air, and giving back oxygen – all of which are the sine qua non of our own lives.  In this memoir, each of these parallel paths – her life and plants’ lives – informs the other.  In both, the challenges are many and the chances of survival often seem staggeringly slight.  

Describing how the first root from a seed risks it all by extending into the ground, she writes,

The root grows down before the shoot grows up, and so there is no possibility for green tissues to make new food for several days or even weeks.  Rooting exhausts the very last reserve of the seed.  The gamble is everything and losing means death.  The odds are more than a million to one against success.  (p. 52, paperback edition)

Later, she observes, “Plants have far more enemies than can be counted.  A green leaf is regarded by almost every living thing on Earth as food.”  (p. 104)

When Jahren reflects on her career, she recounts some of the slings and arrows she’s endured as a woman in science.  Just a few of them include:  feeling the need to avoid certain paleontologists in the field (“knowing that they would never accept me as having a legitimate intellectual claim to the site,” p. 197), overhearing male, academic colleagues gossiping about her sexual orientation and commenting on her appearance (p. 127), and being banished from her own laboratory by a department dean at Johns Hopkins University who, it would appear, was uncomfortable being around a very pregnant woman which she was at the time (p. 216).  She sums up the conflicting and damning messages she’s received as a female scientist by observing,

I have been told that I can’t do what I want to do because I am a woman, and I have been told that I have only been allowed to do what I have done because I am a woman. . . . I have been admonished for being too feminine and I have been distrusted for being too masculine.  I have been warned that I am far too sensitive and I have been accused of being heartlessly callous.  (p. 277)

But that struggle to survive has a silver lining.  Regarding the sexist messages sent her way explicitly or implicitly, she asserts,

Such recurrent pronouncements have forced me to accept that because I am a female scientist, nobody know what the hell I am, and it has given me the delicious freedom to make it up as I go along.  (p. 277)

And therein lies the profound allure of the book, accompanying her as she makes it up from childhood to life as a professional scientist, shaping a unique career path.  In the process, she establishes multiple laboratories, replicating the comforting and protective environment she enjoyed with her father as a child; she bonds to a colleague, Bill, whose personality and behavior puts off some people, but who is a deep friend and amazingly productive over the years in her laboratories; she struggles with and ultimately takes control of her bipolar disorder; and, through it all, she conducts cutting edge research.

Jahren's own efforts to reshape her academic environment find a striking (almost metaphorical) parallel in the research question she and Bill pursue in a spur-of-the-moment project they undertake during a trip to Ireland.  One day, while getting completely soaked in the rain, they observe that the very green, spongy mosses on the top of a hill seem as abundant and healthy as those living at the foot of the hill where clearly more water is available.  How does that happen?  She notes that plants have traditionally been considered passive participants in their environment, growing only when all of the requisites (water, sun, warmth) have been assembled.  In essence, they are seen to be at the mercy of what the environment offers them and when.  But what she and Bill are seeing suggests that these mosses may have taken things into their own hands (so to speak).

What if this moss had moved into an area, deemed it not wet enough, and proceeded to change this high ground into the soggy mess it preferred, causing what was previously heterogeneous to evolve into a uniformly green expanse?  What it the landscape wasn’t setting the stage for plants, but the plants were setting their own stage, green begetting green begetting green?  (p. 247)

It’s profound question and they spend days collecting samples of mosses in a thousand vials from different sites.  Sadly, on this occasion their research ends disaster, at least in the short term.  The vials fail to make it through security at the airport because she hasn’t arranged for official permits to conduct this research project.  (Clearly, governments have no patience with serendipity).  I’ll admit that I was disappointed that Jahren left me high and dry at this point because she doesn’t return to this research question either confirming or rejecting the insight that undergirds it.

As an aside, I have to say that an aspect of this Ireland adventure particularly warmed my heart.  As someone who has often failed at the “name that species” test, I appreciated the struggles she and Bill have identifying the moss species they are collecting.  She notes, “We settled onto our knees and began to take inventory of the species near us.  After two hours, we were pretty sure that we’d found Brachythecium thanks to its furry, leggy appearance up close.”  (p. 248)  That’s about par for the course.  Don’t try to name that species unless you’re willing to invest a lot of time with relatively little to show for it.  That they only came up with the genus of this moss and  punted as to the actual species makes this even more delightful to me.

I’m not quite sure where I come down on the title Jahren chose for the book.  Is this a bitter, and perhaps sarcastic, jibe at the sexism in sciences?  Is this a label she embraces as emblematic of the freedom she’s attained by shattering the expectations for a woman in science?  Both?  Neither?

The misperception of mine that Jahren forced me to confront?  As I read the book, I mentally outlined the blog post I would write, one that would not only review the book, but also draw attention to a recurrent theme of this blog, that of the highlighting of the role of women doing science, paleontology in particular.  Only that recurrent theme turns out not to be real.  Yes, there are posts that describe the work and sometimes the lives of women in science, among them are those on Barbara McClintock, Julia Anna Gardner, Mary Anning, Ruth Patrick, Jennifer Clack, Joan Wiffen, and Elsa Panciroli.  But the small clutch of posts that can be said to have done that is just that, small.  Disappointingly small.  Not until I really looked back at the 333 posts I’ve written over the past 15 years did I realize how male-dominated they are.  True, that reflects the reality of the gender distribution within the sciences, but I had the perception that I was, in some very small way, challenging that status quo.  The reality is different; I haven’t actually done anything approaching that.

Why my misperception?  Perhaps the very rarity of such posts meant they stood out and I was more likely to remember them.  Perhaps this little group of posts seemed enough to me, an adequate nod in the direction of gender equality, a sufficient salute to women doing science.  I certainly hope it isn’t because I subconsciously believe that it’s a rare woman who can do science.

My reading on the issue of women in science has made me realize that that last possible explanation is, even today, very much a likely root cause of the very skewed gender distribution in the sciences.  In her analysis of the question of “Why Are There Still So Few Women in Science?”, writer Eileen Pollack, who earned a bachelor’s degree in physics from Yale in 1978 (one of the first two women ever to do so), disposes of the most malevolent explanation for the paucity of women in the sciences.  “That the disparity between men and women’s representation in science and math arises from culture rather than genetics seems beyond dispute.”  (The New York Times Magazine, October 3, 2013.)  Indeed, she observes, “The most powerful determinant of whether a woman goes on in science might be whether anyone encourages her to go on.”

Pollack recounts how, years after she graduated, when she interviewed the Yale math professor who was the supervisor for her senior thesis and who never encouraged her to pursue graduate studies, she challenged him on the continued dearth of women professors in the Yale math department.  He paused a bit, then commented, “I guess I just haven’t seen that many women whose work I’m excited about.”  But then a realization seemed to dawn on him.  “Maybe women are victims of misperception.”  Yes, yes, yes.  It’s a mindset that seems unable to entertain the idea that more than a few women can do science, that women actually belong in the sciences.  How revealing that this math professor is only now fumbling his way to that realization.

Of course, I probably shouldn’t talk.

The Fate of Islands - Forbidden and Otherwise

This summer, I introduced my granddaughter to the cooperative board game Forbidden Island (Gamewright Games), an engrossing game in which the players work together to gather certain treasures on an island before it, the players, and the treasures sink into the depths.  The island’s geography is different for each game but the peril is constant:  randomly, parts of the island will sink and ultimately disappear.  She took to it completely, quickly mastering the game’s rules and nuances.  The many times I played it over the past month may partly explain the present post.  That, and the fact that the population dynamics on islands are of great interest to biologists and figure prominently in evolutionary theory – species finding themselves on islands, isolated from their counterparts elsewhere, have the opportunity to evolve differently.

This post is somewhat stream-of-consciousness, segueing as it does from one island to another, leading to no real twist or hook at the end. 

I was mesmerized by an article in the most recent issue of LivingBird titled Garden of the Gulls and written by Hugh Powell.  (Powell, 2022.  Full citations and links to references are listed at the end of this post.)  His article describes some of the population dynamics of species on the volcanic island of Surtsey which came into being beginning in 1963, rising violently some 10 miles off the coast of Iceland.  The three stamps below issued by Iceland in 1965 depict Surtsey at three different stages of its initial development:  November 1963, April 1964, and September 1964.

Not surprisingly, given that LivingBird is a quarterly publication of the Cornell Lab of Ornithology, Powell’s article highlights the role that birds, particularly seagulls, have played in fostering the diversity of the flora and fauna population on the island.  This emphasis is completely justified because birds have been critical to Surtsey.  Overall, this is a story of species immigration and the struggle for survival.  The trajectory of the island’s floral and faunal species population has been dictated by a complex interplay of biology, geography, and geology.

The image below of contemporary Surtsey is from Google Maps.

Scientists took full advantage of the opportunity offered by the island’s birth to study in detail the process by which it, initially completely devoid of life, became populated.    Even amid ongoing eruptions, molds, bacteria, and fungi appeared, as did the first vascular plants (1965).  In the ensuing decades, new species came to Surtsey via ocean currents, winds, and birds.  The document prepared in 2007 as part of the successful effort to add Surtsey to UNESCO’s World Heritage List (Baldursson, 2007) identified three periods in the populating of the island:  an initial decade with a burst of new species appearing and some, but not all, becoming established, followed by a decade of “stagnation” with little growth in diversity, followed by a plant and animal population boom, fueled largely by a large community of breeding seagulls.  As Hugh Powell writes in his LivingBird article:  

Plant diversity had plateaued by the 1970s with fewer than 20 species established, and it didn’t take off again until a gull colony developed in 1986.  The gulls, mostly Lesser Black-backed along with Great Black-based, Herring, and Glaucous – carried with them not just new kinds of seeds but also fertilizer in the form of nitrogen-rich guano.  (Powell, 2022, p. 44.)

The guano nurtured a “lush green meadow” that, by 2013, according to Powell, covered roughly 30 acres on the island, “supporting twice as much plant diversity and five times more biomass than the rest of the island.”  (Powell, 2022, p. 44.)

Where have the species found on Surtsey come from?  Those established on the island reflect those on nearby islands in the Westman archipelago of which it is a part and on mainland Iceland.  The UNESCO nomination document notes that the vascular plant species on the island are mostly ones common in the archipelago, supporting the notion that those islands are the primary source of colonizing species.  Further, all of the Surtsey plant species are found on the Icelandic mainland, and “there has been no indication of species colonising the island from distant sources.”  (Baldursson, 2007, p. 28.)

The history of other islands in the archipelago are a window to Surtsey’s future.  Geologically, Surtsey has spent six decades being eroded by wind and water.  In its first forty years, the island shrank by half.  At its maximum size in 1967, the island was approximately 1 square mile in area; by 2004, it was down to just 0.5 square mile.  Powell describes the fate that awaits Surtsey.  Erosion will continue to eat away at the island:

the low-lying plains will disappear (including the present gull colony), and the hard crater walls will become steep-sided seacliffs where murres and Razorbills will nest alongside the fulmars and kittiwakes already present.  Atop the island, a thick turf will develop dominated by just a few grass species.  (Powell, 2022, p. 46.)

As he reports, the plant population boom has already ended and a downward trajectory has taken hold.  The UNESCO nomination document notes that the shrinking of the island’s above-sea landmass has followed a relatively steady pattern.  As a result, the authors conclude the island will come to resemble, in particular, two other islands in the archipelago formed in a similar fashion some 6,000 years ago and long since eroded to the core of the volcanos which created them.  They predict that Surtsey in that form “will survive for a long time, probably for thousands of years.”  (Baldursson, 2007, p. 56.) 

The Surtsey article dredged up from the deep recesses of my memory a different, but very much related, island story, one focused on an experiment conducted in the 1960s by the renowned naturalist Edward O. Wilson and his student Daniel S. Simberloff.  I certainly wasn’t aware of the experiment when it was ongoing or when the initial research articles were published in 1969.  (Simberloff, 1969a; Simberloff, 1969b.)  Rather, it was Wilson’s excellent memoir published a quarter of a century later (Wilson, 1994) that handled that introduction.

As Wilson recounts it, in the early 1960s, he and ecologist Robert MacArthur had developed a mathematically-based hypothesis of island biogeography.  He writes in his memoir,

We had conjured a plausible image of the dynamic equilibrium of species, with new colonists balancing the old residents that become extinct, but we could offer very little direct evidence.  There are few places in the world where biologists can study the approach to equilibrium on a large scale.  (Wilson, 1994, p. 260.)

A recent assessment of the continuing importance of island-based biological research defines MacArthur and Wilson’s “equilibrium theory of island biogeography” as

a theoretical model . . . that postulates that the number of species present on an island will be determined by the dynamic relationship between immigration and extinction rates.  In turn, immigration rates depend greatly on the island isolation, while extinction rates are mainly associated with island area.  (Santos, 2016, p. 753.)

That same assessment considers the MacArthur/Wilson theory to have been highly significant, shifting the paradigm of island research and fostering development of conservation theory.

That lack of “direct evidence” prompted Wilson and Simberloff to fashion in the early 1960s an experiment that could generate data to test the equilibrium theory of island biogeography.  Persuaded that natural experiments in which islands were denuded of species – such as through volcanic explosions or devastating hurricane hits – offered little prospect of generating the necessary data in a reasonable length of time (Wilson suggested 10 years) showing how life returned to such areas, Wilson and Simberloff elect to fumigate six small mangrove islands in the Florida keys, eliminating all insect life on those islands.  In addition to the total mortality of all insects on this tiny islands, some of mangrove trees suffered damage from which, Wilson and Simberloff report, they mostly recovered.  The authors don’t note that any vertebrate animals were adversely affected by the fumigation.

Of the results of this experiment, Wilson writes that “the cruder predictions of the theory had been met.”  (Wilson, 1994, p. 280.)  In the paper on the initial results, Simberloff and Wilson posit that the strongest evidence from this experiment that a specific dynamic equilibrium of species exists for any island was that the number of species on each island post-fumigation returned “approximately” to its pre-fumigation number with a “rough oscillation about this number.”  (Simberloff, 1969b, p. 285.)  Species turnover was speedy as the theory posited it would be on small islands.

I remember my initial reaction to reading Wilson’s account of the experiment – dismay.  It seemed to be going down the slippery slope of the ends justifying the means, distressed as I was by rendering each of these mangrove islands into a killing field.  Admittedly, I had no idea of the importance of the experiment and, even now, I still don’t.  How critical were these data to the significant role subsequently played by the MacArthur/Wilson theory in island research and conservation?  I do suspect that “permission to wipe out animal populations on federally protected land” wouldn’t be granted today.  Back then, permission was readily forthcoming.  (Wilson, 1994, p. 269.)

It's striking that, at the time when Wilson and MacArthur were fashioning and publishing their theory, Surtsey was being born.  What did Wilson think of the role that research on Surtsey might play?  In the methodology paper that he and Simberloff published in 1969, they acknowledge the emergence of this new island and the research then underway to track its population, but immediately discount its utility because of “the infrequent natural occurrence of such events . . . .”  (Simberloff, 1969a, p. 268.)  Rather than taking advantage of such a natural experiment, the authors consider two alternatives.  The first was, in my opinion, a straw man – “produc[e] new islands similar to natural ones.”  The second was the only viable option in their eyes – “sterilizing preexisting islands.”

I would have voted for natural experiments, but I think I’ll stick to Forbidden Island where I understand the dynamics of the game and there’s not much at stake even as the island disappears under my feet.

References

Baldursson, Snorri, and Álfheiður Ingadóttir, Nomination of Surtsey for the UNESCO World Heritage List, 2007.

Powell, Hugh, Garden of the Gulls, LivingBird, Summer 2022, Volume 41, Number 3.

Santos, Ana M.C., et al., New Directions in Island Biogeography, Global Ecology and Biogeography, Volume 25, Number 7/8, 2016.

Simberloff, Daniel S. and Edward O. Wilson, Experimental zoogeography of Islands:  Defaunation and Monitoring Techniques, Ecology, Volume 50, Number 2, 1969a.

Simberloff, Daniel S. and Edward O. Wilson, Experimental Zoogeography of Islands:  The Colonization of Empty Islands, Ecology, Volume 50, Number 2, 1969b.  []

Wilson, Edward O., Naturalist, 1994.

Plants at the Center

This post is nothing like I planned.  When I retreated to my rundown summer cottage on the North Fork of Long Island, I took along paleontologist Steve Brusatte’s new book, The Rise and Reign of the Mammals:  A New History From the Shadow of the Dinosaurs to Us (2022).  Brusatte’s a wonderful writer of popular science, offering graceful prose and clear exposition.  His previous book, The Rise and Fall of the Dinosaurs (2018), is one of the best I’ve read in that genre (meriting a review of its own).  

But, no review here, and, mostly, no mammals either, not even mice (which comfortably, if messily, overwintered in a couple of dressers).  Instead, flora are at the center of this unplanned post (quite unplanned and it shows).

My intentions were deflected by three things.  The first two, ironically enough, came directly from Brusatte’s own book in which he makes a couple of startling and important points regarding plants, observations that for me were point-of-view shifting.

The first comes when he describes how, in the late Carboniferous Period, amniotes found themselves favored over amphibians by dramatic changes in the environment, changes that precipitated the so-called Carboniferous Rainforest Collapse (roughly 307 to 303 million years ago).  (Amniotes are those animals whose embryonic development occurs inside amnion tissue either within eggs or the uterus.)  A much drier climate upended the rainforests whose flora were replaced by more drought tolerant plants.  The overall impact on plants was devastating.  It’s what Brusatte writes about the context of this plant extinction that was eye-opening for me. 

All told, about half of the Pennsylvanian plant families were extinguished.  This is one of only two mass extinctions recognized in the plant fossil record.  (p. 15, emphasis added)

Wait, what?  Plants have only been through two mass extinctions while animals, I know, have five on their resume?  This Carboniferous one for plants does not coincide with one for animals while the second plant mass extinction does, coming at the end of the Permian Period, one of the big five for animals.  This difference between the experiences of plants and animals was news to me.  It also immediately raised the question, why have plants come relatively unscathed through events that devastated animal life, events like the end-Cretaceous extinction that did in the non-avian dinosaurs?

Brusatte cites a fascinating 2014 study by Borja Cascales-Miñana and Christopher J. Cleal in support of this assertion about plant extinctions (The Plant Fossil Record Reflects Just Two Great Extinction Events, Terra Nova, Vol. 26, Number 3, 2014).  These authors suggest that plant taxa have proven, based on the fossil record, to be

far more resilient than animal taxa to many types of major ecological disturbance such as pollution caused by igneous province eruptions or bollide [asteroid or meteor] impact.  (p. 198)

They posit that plants may be able to survive relatively short-lived environmental disturbances, that greatly affect animals, if plants’ seeds and spores have a viability that exceeds the duration of the disturbance.

This puts plants in a whole new light.

As if that weren’t enough, a second plant-related point Brusatte makes was also quite striking, ensuring that mammals would be displaced in this post.  He describes the roles that plants have played in the evolution of animals.  Yes, it’s a dance with all parties affected in some way, but Brusatte gives certain plants the lead.  I was (to put it mildly) gob smacked when he calls the widespread appearance of angiosperms (flowering plants) “the driving force of Cretaceous evolution.”  (p. 135, Brusatte’s emphasis)

Like a maestro furiously sweeping her baton, the angiosperms steered the bugs, dinosaurs, mammals, and other animals in unanticipated new directions, leading an evolutionary movement that reshaped the earth.  As a result, today angiosperms are dominant; they are, by far, the most abundant plant type in nearly every terrestrial landscape on the planet.  (p. 135)

The flowering plants wielded their evolutionary power, first as a food source which animals evolved to better take advantage of.  Second, the angiosperms' impact on insect evolution was profound; pollinators evolved to derive energy from the flowers.  These pollinators, in turn, served as a new, important food source for animals, which (in this interconnected dance) evolved in new ways.

When Brusatte writes that angiosperms are “the most abundant plant type in nearly every terrestrial landscape on the planet,” he isn’t specifically referring to the woodlands which nestle my summer cottage, but he could have.  It’s this setting into which I retreated to write about mammals, a setting that has whispered, "Skip the mammals, embrace the plants."

After a wet spring and early summer, this area is awash in vegetation.  Though old gnarled oaks tower over the woods, the deep, cool, green shadows here are cast by myriad maples – from the Norway maples with their almost translucent leaves when the sun is behind them to the broad- and dense-leafed sycamore maples.  These are trees that, under most circumstances, draw my eyes, demanding attention as they reach for open spaces in the canopy.  This year, though, it's the small floral denizens of the woodland edges and the overgrown strip along the nearby railroad tracks that have really captured me.

For more than a decade now, during my summer visits here, I’ve noted in my copy of Peterson First Guide to Wildflowers of Northeastern and North-Central North America (1986), by Roger Tory Peterson, the species I’ve found along the same expanse of the wood’s edge and a bit of the land abutting the railroad tracks.  My sole requirement for being listed is that the plant be in bloom.  I recognize that this First Guide is very incomplete; Peterson called it “smaller” and “simpler” than even a guide for the novice.  Still, it’s been a helpful place to start and I’ve added, on the inside of the back cover, the names of a few missing species that I’ve found.  My overall count of species now exceeds 30.  Not unexpectedly, after awhile, new additions have become very few and far between, and my interest has waned.  Except this year I discovered two species (new to me) that have appeared in robust numbers; neither can be found in the Peterson First Guide.

This small flower I’ve confidently identified only as to genus, Froelichia, whose common name is snakecotton.  The genesis of that common name is fairly obvious.  From a distance, an expanse of these white flowers waving on their extended stems do appear cottony (though not so up close).  I suspect this is actually the species Froelichia gracilis, also known as slender snakecotton.  The U.S. Department of Agriculture’s Plant Database shows this species present on all of Long Island and the picture provided seems to match mine.

This is Berteroa incana, called hoary alyssum which the USDA Plant Database records as found on Long Island.  I turned to the Compact Oxford English Dictionary for an explanation of the common name which didn’t seem all that common.  Something hoary is greyish white (or, and I didn’t know this, something “old and trite”).  Alyssum is the (non-scientific) name for this kind of plant, coming from the Greek word alusson, which, in turn, means “without” (a) “rabies” (lussa).  This harkens back to herbalists’ use of the plant.  That said, there’s a large red warning flag attached to hoary alyssum because it is poisonous to horses.

And, so, what was planned as a paean to mammals is, instead, a salute to my new knowledge about plants:  plants as survivors of many catastrophic events that decimated animal ranks, and flowering plants as drivers of animal evolution.  Given those attributes, and the striking beauty (and bit of danger) of the wildflowers I discovered this summer, it seems quite appropriate to put plants at the center.

Leopold Bloom, An Everyman Seduced by Science

For a century, Leopold Bloom and young Stephen Dedalus have woven intersecting paths through Dublin during Thursday, June 16, 1904, and into the wee hours of the next day.  Their peregrinations, traced in the densely rich pages of James Joyce’s Ulysses, first saw the light of day for us to enjoy with the publication of the novel in 1922.  Pictured below is number 302 of the 1000 numbered first edition copies published by Sylvia Beach’s Shakespeare and Company.  (This image was taken by Geoffrey Barker.  Available from Wikimedia Commons, it is reproduced under Creative Commons Attribution-Share Alike 4.0 International License.)

The scaffolding of the novel is Homer’s Odyssey; its episodes track with those experienced by Ulysses in his quest to return from Troy to his home in Ithaca and to his wife Penelope.  Beyond the title, our knowledge of the embedded road signs to the Homeric structure are the product of Joyce's own schema and the extensive scholarship that the novel has supported for a hundred years.  Joyce would have had it no other way, having said his masterwork would “keep the professors busy for centuries.”  [Later edit:  I rewrote this paragraph after posting it because I misstated things in a way worthy of Bloom.]

I made several failed attempts over the years to read the novel’s nearly 800 pages, but, this year, I succeeded, prompted by the occasion of the centenary of its publication and by my decision to follow a particular approach to tackling this masterpiece:  go with the flow, read primarily for the plot, and don’t sweat all the myriad details.  This approach was inspired by JoAnn Greco’s article Unlocking Ulysses (Johns Hopkins Magazine, Volume 74, Number 1, Spring 2022).  In it she quotes Douglas Mao, chair of Johns Hopkins University's English department, "I think basic comprehension is what first-time readers want."  And so, in his classes, he focuses on "sticking to the text and understanding what is happening in the story."  Of Greco's own first reading, she admits "I slogged and skimmed when things got tedious."  Mao posits that a first reading is just preliminary to re-immersing for the second and third readings.  Well, maybe later.

I came to this foray equipped with the complete edition of the novel published in 1961 by Random House, an edition tied page-by-page to an excellent guide to the book’s obscurest references, Ulysses Annotated:  Notes for James Joyce’s Ulysses, by Don Gifford with Robert J. Seidman (1988).  I was helped by Edward A. Kopper, Jr.’s Cliffs Notes on Joyce’s Ulysses, (1981) which well defines the broad contours of the events of the novel.

Ulysses’ “hero” Leopold Bloom is a complex character and, as my companion for experiencing the events of June 16th and early June 17th, I found him:

gentle, often charitable, generally well meaning, loquacious, opinionated (about everything and often wrong), unintentionally comic, very sensitive of being an outsider, frustratingly passive, furtive, and sexually driven.

What a wonderful creation.

Connection of Bloom to this blog?  With this reading, it came clear how much Bloom seeks to demonstrate to himself and those he encounters in his travels that he is privy to the mysteries of science (writ large).  He wants to don the mantle of the scientific cognoscenti, despite having only a limited and fragmented understanding of what he propounds.  It’s hard not to laugh at him as he remembers and misremembers scientific principles, misapplies them, attempts to expound some scientific explanation only to lose the thread.  In finding this amusing, I’m laughing at myself and my own bumbling aspiration to scientific mastery.

In episode 17 (Ithaca), a fascinating section featuring a series of questions with answers about Bloom and Dedalus, one stood out for me:

What two temperaments did they individually represent?

The scientific.  The artistic.  (p. 683)

Bloom’s is the “scientific” temperament.  I should note that it doesn’t take until this late point in the narrative to recognize that Bloom and Dedalus are like chalk and cheese, and to appreciate the nature of Bloom’s scientific temperament.

Here’s a telling example of how Bloom manifests that temperament.  Very early in the novel, he sets out walking from his house en route to Paddy Dignam’s funeral.  He pauses before the window of the Belfast and Oriental Tea Company store.  Its display leads him to think about, among other subjects, Ceylon, tropical heat, lethargy; his mind comes to rest on a mental image of someone floating on his back in the Dead Sea reading a book.  Bloom thinks:

Couldn’t sink if you tried:  so thick with salt.  Because the weight of the water, no, the weight of the body in the water is equal to the weight of the.  Or is it the volume is equal of the weight?  It’s a law something like that.  Vance in High school cracking his fingerjoints, teaching.  The college curriculum.  Cracking curriculum.  What is weight really when you say the weight?  Thirtytwo feet per second, per second.  Law of falling bodies:  per second, per second.  They all fall to the ground.  The earth.  It’s the force of gravity of the earth is the weight.  (p. 72, "fingerjoints" and "Thirtytwo" are as Joyce penned them.)

How funny, how real, how familiar.

In episode 16 (Eumaeus), late at night, Bloom and Dedalus walk to a cabman’s shelter (a structure where the cab drivers can get hot food and tea).  Among the topics of their conversation (in which they talk past each other) is the human soul.  Dedalus says that others call it a “simple substance and therefore incorruptible.”  (p. 633)  Bloom (Joyce notes he is “a bit out of his sublunary depth”) is compelled to respond, focusing on the adjective “simple”:

—Simple?  I shouldn’t think that is the proper word.  Of course, I grant you, to concede a point, you do knock across a simple soul once in a blue moon.  But what I am anxious to arrive at is it is one thing for instance to invent those rays Röntgen did, or the telescope like Edison, though I believe it was before his time, Galileo was the man I mean.  The same applies to the laws, for example, of a farreaching natural phenomenon such as electricity but it’s a horse of quite another colour to say you believe in the existence of a supernatural God.  (p. 634, "farreaching" - sic)

Bloom so wants to be able to interact with Dedalus on the latter’s artistic and intellectual level, but he cannot.  He’s out of his depth regarding nearly everything under the moon on that June night.  But he cannot not engage Dedalus in conversation, regardless of how little of substance he has to offer.

Bloom, a decidedly social creature, must offer, whatever the situation, an opinion or an explanation, even if he only has only the barest inkling of what’s relevant or what’s wanted.  The people around him recognize this and, in the course of the novel, comment on it.  For instance, earlier in the day (episode 12 (Cyclops)), as Bloom goes in and out of Barney Kiernan’s pub, he is clearly not welcome.  Still he feels the need to engage in the discussions of a group of raucous, angry, disgruntled men, led by the anti-Semitic, Irish nationalist character identified as "Citizen."  At one point, the conversation turns to record distances of shot put throws.  The narrator of this episode (quite acerbic in his comments) observes:

So off they started about Irish sport and shoneen games the like of the lawn tennis and about hurley and putting the stone and racy of the soil and building up a nation once again and all of that.  And of course Bloom had to have his say too about if a fellow had a rower’s heart violent exercise was bad.  I declare to my antimacassar if you took up a straw from the bloody floor and if you said to Bloom:  Look at, Bloom.  Do you see that straw?  That’s a straw.  Declare to my aunt he’d talk about it for an hour so he would and talk steady.  (p. 316, Gifford in Ulysses Annotated notes that a shoneen is a “would-be gentleman.”)

This need to engage and expound, coupled with a faulty grasp of the science, is a recipe for disaster, as it would be for any avocational science lover.  Bloom, a comic hero, is human to a fault, and, in his mangling of science, proves he is truly an Everyman seduced by, but not master of, science.  I can relate to that, having been there more often than I care to admit (and certainly, at times, in the posts of this blog).

The Serrations of the Teeth of the Tiger Shark Galeocerdo cuvier – Beautiful, Another Adjective to Apply

The teeth of the extant tiger shark Galeocerdo cuvier are among my favorite shark teeth for two primary reasons:  their overall shape (shared by others, all extinct, in this genus) and their serrations, wonderfully abundant in this particular species.  This post has gone through myriad permutations, beginning with an attempt to capture my confusion over the scientific literature on this species' serrations (difficult to write and uninteresting to read).  I have decided, instead to write briefly about what I think I know about the serrations of the G. cuvier which includes a discussion of the descriptive terminology applied to them, as well as a short review of what I understand about their function.

G. cuvier, the sole living member of this species, is a large, dangerous denizen of the world’s oceans.  It dates back to the Pliocene Epoch (5.3 to 2.6 million years ago) (some research may push the shark’s origins into the mid-Miocene Epoch, perhaps 13.8 million years ago).  (For the earlier date, see Türtscher, 2021.  All references are presented at the end of this post.)  G. cuvier teeth have a striking morphology, often and appropriately described as cockscomb-shaped.  It is quite distinctive and, so, it's hard to confuse these teeth with those from other species.  The illustration below captures that recognizable shape.  Three key aspects of that shape are marked:  the mesial cutting edge, the distal cutting edge, and distal heel.  The front of the mouth is at the left in this image.  (This image is based on one appearing in Türtscher, 2022.) 

That each (extant and extinct) species in the Galeocerdo genus features some array of serrations renders them irresistible.  But G. cuvier teeth are very special in that regard:  not only is the entire outer edge of their crown serrated, but the serrations on both its mesial cutting edge and distal heel are themselves serrated.  Serrated serrations!  What’s not to like?

The first picture below shows the lingual (tongue) side of a tooth from a modern adult G. cuvier.  The distance from edge to edge of the very bottom of the tooth is 25 mm.  The second picture shows the labial (lip) side of an adult G. cuvier from the Yorktown Formation at the Lee Creek Mine.  The measurement across the bottom is the same as for the first tooth.  This particular specimen dates from the Pliocene Epoch.

Serration Terminology

The scientific terms used to distinguish among the general characteristics of shark dentition are challenging, very specialized, and quite alien.  To wit, polphyodonty (teeth are continuously replaced throughout the life of the shark), homodonty (teeth are all the same shape), heterodonty (there are different tooth shapes in the same individual), monognathic heterodonty (tooth shape changes moving from front to back along the jaw), dignathic heterodonty (different shapes in the upper jaw compared to the lower jaw), and gynandric heterodonty (teeth of the same species differ in shape by sex).  (Türtscher, 2022.)  Some of these characteristics vary in the same species depending upon such factors as age or mating season.  Not surprisingly, these are terms that I come to this literature prepared to decipher (a cheat sheet helps).

The G. cuvier dentition is largely the same morphologically from front to rear and top jaw to bottom jaw.  They do vary by ontogenetic stage of development, particularly with regard to the extent and robustness of the serrations.  (Türtscher, 2022, p. 10.) 

Though these scientific terms present a hurdle to the casual reader of this literature, my attention is drawn repeatedly to the various (and sometimes inconsistent) uses of adjectives to describe the serrations on these teeth.

Primary and secondary are the most precisely applied adjectives.  Indeed, a key distinction for serrations on G. cuvier teeth is between two types:  primary serrations and secondary serrations.  The large serrations that occur on the mesial cutting edge and the distal heel of these teeth are primary serrations.  The smaller serrations that line the distal cutting edge and also appear on the edges of (and between) the primary serrations on the mesial cutting edge and distal heel are called secondary serrations.  These different types of serrations are marked below in the closeup of the distal cutting edge and part of the distal heel of the specimen shown in the first picture above.

In their study of serrated shark teeth (blue shark, white shark, and tiger shark), Moyer and Bemis name and distinguish these two types of G. cuvier serrations.  Significantly, their analysis shows an underlying histological difference between them.  Primary serrations consist of three layers of enameloid with a partial internal filling of dentine; secondary serration generally have only two of the three enameloid layers and no infilling dentine.  (Moyer and Bemis, 2017, p. 105.)  I will outline later what Moyer and Bemis posit regarding the function of these secondary serrations.

Once I move beyond that central distinction in the kinds of serrations on the G. cuvier adult teeth, there’s no consistency in the terms used but in most cases context suggests intended meaning.

Serrations with serrations.   These have been described as compound (Kent, 2018, p. 108), complex (Kent, 1994, p. 96; Türtscher, 2022, p.12), and double (Cappetta, 1987, p. 17; Türtscher, 2022, p. 2).

Serrations without serrations.  These have been called simple (Kent, 1994, p. 96) and singly serrated (Türtscher, 2021, p. 584).

A bit more problematic is that these various adjectives are mixed and matched in different ways.  For instance, Cappetta distinguishes between simple and double serrations.  (Cappetta, 187, p. 17.)  Then there’s the application of the adjective compound to describe the overall configuration of all serrations on the G. cuvier, which are a combination of different types of serrations.  Türtscher and her colleagues do this in the following description of adult G. cuvier teeth:

The crown is completely serrated with compound serrations, whereby large primary serrations are located on the mesial cutting edge and the distal heel, while secondary serrations are situated on and between primary serrations as well as on the distal cutting edge.  (Türtscher, 2022, p. 3.)

Function of G. cuvier Serrations

Why serrations and why serrated serrations?

The teeth of G. cuvier are characterized as cutting type teeth, a category of tooth that includes broad and relatively flat teeth with a cusp that often is curved toward the rear of the mouth.  Moyer and Bemis argue that stress on the G. cuvier tooth concentrates on the large notch where the distal cutting edge meets the distal heel (see outline of the G. cuvier tooth above).  This, they suggest, may help the tooth cut through tough prey.  (Moyer and Bemis, 2017, p. 107.)  That’s quite relevant given that the adult diet does focus on tough prey, such as mammals, other sharks, rays, and sea turtles.  (Türtscher, 2022, p. 12.)

Adding serrations to these teeth boosts their effectiveness.  (Cappetta, 1987, p. 16-17.)  Frazzetta concludes:  “Serrated teeth can make greater use of the available biting forces, and they have greater cutting effect than do smooth-edged teeth.”  (Frazzetta, 1988, p. 93.)

But serrated serrations apparently are a rarity, so, to what end did they appear in the Galeocerdo lineage?  The secondary serrations on the edges of the primary serrations may make the cutting edges more efficient when the tiger shark engages in its typical vigorous head shaking when attacking prey.  The notches marking the juncture of secondary and primary serrations may also serve as points at which stress is concentrated, reducing the wear on the primary serrations, helping to keep them functional longer.  (Moyer and Bemis, 2017, p. 107-108.)  Ultimately, for the G. cuvier, secondary serrations “are probably linked to the prominence of hard-shelled prey in its diet, specifically sea turtles, whose shells are composites of bone and keratin, presenting a unique challenge to predators.”  (Moyer and Bemis, 2017, p. 109; see, also, Türtscher, 2022, p. 12.)

I think the importance of secondary serrations, including those that run along the edges of the primary serrations on the G. cuvier’s mesial cutting edge and distal heel, requires a bit of elaboration.  The Galeocerdo, like all sharks, is polyphyodont, that is, it is constantly replacing its teeth.  As a result, the protective role that secondary serrations may play for primary serrations need last only until the tooth is replaced.  That’s actually quite efficient considering its prey.

Closing with reference to the G. cuvier’s diet is appropriate, I think.  Yes, its teeth are wonderfully structured for the role they play in enabling this fish to consume its prey, but this shark is not picky.  In addition to its living prey, it adds carrion and a very wide variety of trash to what it swallows, thereby living up to its sobriquet:  “A garbage can with fins.”  (Compagno, 2005, p. 308.)

References

Cappetta, H., Handbook of Paleoichthyology:  Chondrichthyes II:  Mesozoic and Cenozoic Elasmobranchii, 1987.

Compagno, Leonard, et al., Sharks of the World, Princeton Field Guide, 2005.

Frazzetta, T.H., The Mechanics of Cutting and the Form of Shark Teeth (Chondrichthyes, Elasmobranchii), Zoomorphology, Volume 108, 1988.

Kent, Bretton W.  Fossil Sharks of the Chesapeake Bay Region, 1994.

Kent, Bretton W.  The Cartilaginous Fishes (Chimaeras, Sharks, and Rays) of Calvert Cliffs, Maryland, USA, chapter 2 in The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland, USA, edited by Stephen J. Godfrey, Smithsonian Contributions to Paleobiology, Number 100, 2018.

Moyer, Joshua K., and Bemis, William E., Shark Teeth as Edged Weapons:  Serrated Teeth of Three Species of Selachians, Zoology, Volume 120, 2017.

Türtscher, Julia, et al., Evolution, Diversity and Disparity of the Tiger Shark Lineage Galeocerdo in Deep Time, Paleobiology, Volume 47, Number 4, 2021.

Türtscher, Julia, et al., Heterodonty and Ontogenetic Shift Dynamics in the Dentition of the Tiger Shark Galeocerdo cuvier (Chondrichthyes, Galeocerdidae), Journal of Anatomy, April, 2022.