Wednesday, October 30, 2013

Coming Out of Left Field, A Snail Takes a Wrong Turn

The Oxford American Dictionary offers two figurative definitions for left field:  (1) "a position or direction that is surprising or unconventional;" (2) "a position of ignorance, error, or confusion."
A wonderfully funny explanation for the expression that something or someone “came out of left field” or “was out in left field” is premised on the “fact” that roughly a century ago the Chicago Cubs played in the West Side Grounds which had a left field abutting the University of Illinois’ Neuropsychiatric Institute.  So, what came out of, or was in, left field might well have been out of touch, indeed, maybe crazy.  Sadly, that explanation is too good to be true.  Yes, the Cubs played there from 1893 to 1915, but that was well before 1939 when the Neuropsychiatric Institute was built on what had been the West Side Grounds’ left field.  (Rosemarie Ostler, Let's Talk Turkey:  The Stories Behind America's Favorite Expressions, 2008, p. 163.)

One of the better possibilities for the expression's origin rooted in baseball is that many early major league baseball stadiums were decidedly asymmetrical and, apparently, left field was often the deepest part of the ballpark.  So, the left fielder was literally way out in left field (away from the action of the game) and any time he threw a ball back toward the infield, it came from way out of left field.

What came out of left field this past week (via a friend) fit the first Oxford American Dictionary's figurative definition - a surprise (though eventually it led to the second definition).  It was a fossil marine snail shell found on the coastline near the town of Walton-on-the-Naze, in Essex County, England.  This is a Neptunea contraria (Linnaeus, 1771) and dates from late in the Pliocene Epoch (3.6 to 2.6 million years ago).

(Though there’s some debate about the name of the species, I'm sticking with N. contraria as have better and more expert thinkers than I.)

I certainly wasn’t expecting to receive this shell.  What was intended to be the real hook for me about this specimen was that it was still filled with matrix from where it was found, offering an irresistible opportunity to discover microfossils tucked into its curved chambers.  But, frankly, though I’ve begun the exploration of the microfossils (more on that in a later post), I’ve been captured by so much else about this particular fossil that I had to write about that.  Yes, all that came out of left field.

The location where the fossil was found – Walton-on-the-Naze – is a small town located on England’s east coast, on the shores of the North Sea.  The melding of name and location strikes me as quintessentially British.


The Oxford English Dictionary defines naze as:  “A promontory, a headland, a ness.”  The OED observes that its origins are uncertain, though it suggests it may have Scandinavian roots.  Bill Griffiths, in Fishing and Folk:  Life and Dialect on the North Sea Coast (2010, p. 10), speculates that it may derive from the French nez meaning nose.

A view of the area around Walton-on-the-Naze from Google Earth clearly shows the naze, which is the headland, to the northeast of the town, jutting into the North Sea.  Sort of nose-like.

The eroding cliffs from which the fossil came follow that coastline to the northeast.  The London Clay Formation, laid down in the Eocene Epoch (56 to 34 million years ago), forms the base of the cliffs.  That formation is overlain by the Red Crag Formation which is nearly 50 million years younger; this unconformity is the product of marine erosion washing away millions of years of intervening deposits.  The Red Crag Formation, source of this fossil, dates from the late Pliocene Epoch (3.6 to 2.6 million years ago).

Red?  Crag?

Geologist Gerald Lucy explains both in Essex Rock:  A Look Beneath the Essex Landscape (Essex Rock and Mineral Society, 1999).  Let’s take the latter one first.
The word “crag” was formerly a local term used in East Anglia to describe fine gravel and sand but geologists have now adopted it to designate some of the characteristic marine deposits of Pliocene and Pleistocene age in Essex, Suffolk and Norfolk.  (p. 53)
The coloring (more orangey than red to my eye) is, according to Lucy, the result of a several step reaction:  pyrite (iron sulfide) washed out of the underlying London Clay, the iron in the pyrite oxidized into rust-colored iron oxide which, in turn, stained the sand, gravel, and fossils in the Red Crag Formation.  The white marks on the outer lip and interior of the aperture of the N. contraria specimen in the photo above show that the iron oxide did not penetrate into the substance of the shell, at least not this one.  Indeed, the stain scrapped off quite easily from the interior of this shell as I cleared out the matrix.

I am puzzled about one aspect of Lucy’s explanation, precisely how did (does?) the iron from the pyrite or the iron oxide saturate the Red Crag matrix?  Is Lucy asserting that the iron or iron oxide percolated vertically upward from the London Clay into the overlying Red Crag Formation?  It’s unclear from the photographs I’ve seen of the cliffs whether the coloring is more intense where the Clay and Crag are in direct contact and then fades as one moves up the cliffside.  (Have to travel there and see for myself.)

Perhaps the most far out aspect of this whole encounter with this Neptunea contraria fossil is what stares me in the face when I hold the fossil with the aperture toward me and the apex pointed up – the aperture is on the left.  The N. contraria is left-handed or sinistral.

Evolutionary biologist Geerat J. Vermeij notes that left-handedness is a rare species-level characteristic among gastropods, particularly marine gastropod species.  (The Geography of Evolutionary Opportunity:  Hypothesis and Two Cases in Gastropods, Integrative and Comparative Biology, Volume 42, Number 5, 2002.)

Left-handed coiling in gastropods poses a fascinating problem.  On the one hand, according to Vermeij, left-handedness is “unlikely to have significant survival-related benefits.”  In essence, it is “apparently functionless.”  On the other hand, it may have a marginally negative impact.  Research on sinistral members of otherwise dextral species has shown that they may be at some slight disadvantage relative to their dextral brethren (Stephen Jay Gould, et al., Consequences of Being Different:  Sinistral Coiling in Cerion, Evolution, Volume 39, Number 6, November, 1985).  So, Vermeij considers the circumstances under which a “functionless” trait with some slight deleterious effects might actually arise as a species-level characteristic.  He concludes that such a trait might emerge in environments “where resources are abundant” but “where predator-induced selection is weak.”  Intensive predator selection would, presumably, magnify the consequences of the adverse effects of sinistral coiling, explaining its rarity.

More recent research suggests that sinistral coiling in snails may in fact offer some advantages, at least relative to predation by crabs.  Crabs are typically right-handed and apparently have some difficulty managing the process of stripping left-handed snails of their shells.  That begs the question of why more gastropod species aren’t sinistral as a result of this advantage.  Paleontologist Gregory P. Dietl and Jonathan R. Hendricks suggest that perhaps this is an instance of sexual selection and natural selection working to offset each other.  But, ultimately, they throw up their hands and quote biologist and mathematician D’Arcy Wentworth Thompson, who wrote in 1943,
But why, in the general run of shells, all the world over, in the past and in the present, one direction of twist is so overwhelmingly commoner than the other, no man knows.
(As quoted by Dietl and Hendricks in their article titled Crab Scars Reveal Survival Advantage of Left-Handed Snails, Biology Letters, published online on March 21, 2006.)

That left-handedness among gastropods struck early naturalists as something unusual, if not literally a mistake, is evident by the names given some of these sinistral species.  Neptunea contraria is fairly mild – contraria means opposite or contrary in Latin.  But then there is the whelk whose left-handedness earned it the name Busycon perversum (Linnaeus, 1758).  Linnaeus originally named it Murex perversus.  Perversum is Latin for perverse, perverted, crooked, or wrong.

Speaking of which, the earliest description I have found of the Neptunea contraria is in Samuel Dale’s The History and Antiquities of Harwich and Dovercourt, Topographical, Dynastical and Political published in 1730.  Here he compares members of this species to those of a similar species that coils to the right:
They are like the precedent [the ones previously described] in all things excepting in the wrong Turn.  (p. 287, capitalization in the original)
A wrong turn.  A nicely unscientific assessment for a snail that, to these early naturalists, seemed to have come (had the expression been around then) out of left field.

Thursday, October 17, 2013

Cusplet ~ Sound and Sight

This is a small post making a small point or two.

To my ear, there is something melodious and even soothing about the sound of the word cusplet.   Though the word does not appear in the Oxford English Dictionary or, for that matter, in most other dictionaries, it’s not uncommon in the biological and paleontological literature on teeth, particularly shark teeth.  Google’s Ngram Viewer shows that cusplet first appeared in books in English in the middle to late 1800s and really only took hold in the middle of the 1900s.

(The Ngram Viewer is a fascinating tool which gauges the frequency (Y axis) with which specific words or phrases appear by publication year (X axis) among all the words in millions of Google’s digitized books.)

Bretton W. Kent (Fossil Sharks of the Chesapeake Bay Region (1994)), defines a shark tooth cusplet as follows:
a small, enameloid-covered projection lateral to the basal margin of the crown.  (p. 92)
In other words, it’s a little cusp that appears at the base of a tooth’s main cusp.  The sound of the word (at least to me) belies the purpose of this dental feature – grasping a shark’s intended victim.

Visually, for that matter, the cusplets on fossil shark teeth also contradict their predatory purpose, seeming singularly fragile.  Perhaps my reaction to cusplets is a function of how often they have worn away or broken off in the course of the long journey undertaken by fossil shark teeth to reach my hands.  That some cusplets make it through this threat-filled time travel is really quite remarkable.

Take, for example, the cusplets on this sand tiger tooth I recently found at the Calvert Cliffs  The tooth is roughly 16 million years old (mid Miocene Epoch).

I’ve identified this as a tooth from Carcharias reticulata (Probst, 1879), relying on Kent’s Fossil Sharks.  Much of the doubt associated with this identification isn’t a function of my usual waffling.  Rather it stems from debate among the experts because both the genus and species names of this Miocene shark are up for grabs.

Kent’s description notes that teeth from this species are graced with “long, slender cusplets.”  The German priest Dr. J. Probst (1823 – 1905), the first to name this species, identified it as Lamna reticulata and noted that its teeth were distinguished from those of another similar species by “their smaller size and especially by their cusplets.”  (Beiträge zur Kenntniss der Fossilen Fische aus der Mollase von Baltringer, Jahreshefte des Vereins für vaterländische Naturkunde in Württemberg, Volume 35, 1879, p. 145-146.)  To be totally candid, when Probst used the word Nebenspitzen in his description, I departed from Google Translate which rendered that as “secondary peaks.”  “Cusplets” seemed right.

I was momentarily sidetracked when I tried to find out who Probst was.  His birth and death dates come from an article that appeared in the journal Stuttgarter Beiträge Zur Naturkunde in 2002 (Gunter Bechly and Volker J. Sach, An Interesting New Fossil Dragonfly (Anisoptera:  Libellulidae: “Brachydiplacini”) from the Miocene of Germany, With a Discussion on the Phylogeny of Tetrathemistinae and a Fossil List for the Locality Heggbach).  Other than those dates and his two titles – priest and Dr. – I have nothing for him except several papers he wrote, all in German and largely beyond my ken.  Perhaps buried in them is the answer to another question I considered worth pursuing, where did this paleontologically inclined priest come down on evolution?

Both Kent and Probst drew attention to the cusplets on this species, so, it seems appropriate to conclude this “postlet” with a closeup of one of the specimen’s cusplets.

The cusplet has a cusplet.  Actually, Kent notes that this is a possibility with the teeth of this species.  It's quite an accomplishment that these two cusplets survived the vicissitudes of the fossilization process virtually intact.  Admittedly, the secondary cusplet on the other side did not fare as well, but I guess that’s life . . . .

Friday, October 4, 2013

Patrick Principle(s)

My father “influenced me to realize that the most important things in life [are] to understand the natural world and . . . to be kind to my fellow man, even though I might not understand them.”
   ~ Ruth Patrick, Hometown Legends:  Ruth Patrick, WHYY TV, aired October 30, 2004
 Perhaps I’m impressed by trivial connections that I consider insights and the one at the center of this post might be one of those.  Even if that’s true, Ruth Patrick is someone we should all get to know.

Over the past several weeks, I have been reading a couple of informative and entertaining accounts of the Permian extinction, that mother of all mass extinctions – Gorgon:  Paleontology, Obsession, and the Greatest Catastrophe in Earth’s History by Peter D. Ward (2004) and Extinction:  How Life on Earth Nearly Ended 250 Million Years Ago by Douglas H. Erwin (2006).  Ward and Erwin, both practicing paleontologists, certainly know how to write for a popular audience.  Ward’s account focuses on terrestrial extinction, particularly as it is recorded in the bleak and beautiful Karoo region in South Africa.  His is a decidedly more personal story (sometimes too much so) as he plays the starring role; on occasion, it crosses into the “tell all” territory (one wonders whether he has been able to continue to work with at least one of his colleagues, Roger Smith, after the way Smith is characterized in the book).  Erwin’s volume offers a more deliberate explanation of the Permian extinction and a well-structured exploration of the various hypotheses about its causes.  It, too, ventures into the first person at times when it takes the reader into the field.  Good videos of talks on this subject delivered by both authors are available on the web.  There’s Ward’s TED talk and Erwin’s talk at the Santa Fe Institute.

I found one aspect of the aftermath of the Permian mass extinction that both Ward and Erwin describe to be particularly surprising.  Yes, the Permian extinction cut a devastating swathe through the ranks of plant and animal taxa.  For example, according to Erwin, the two pulses of Permian extinction, separated by some 10 million years, eliminated at least 90 percent of all marine species.  I suppose I’d previously assumed (if I'd actually had any coherent thoughts about it) that a devastated, lifeless environment ensued and endured for thousands, hundred of thousands, or perhaps millions of years.  But that’s not necessarily the case.

Erwin opens his book in Utah, where “the Triassic is laid out for anyone who cares to look, although few do,” apparently because the fossils are either scarce or boringly the same.  (p. 1)  Later, he describes formations that were laid down during the early stages of recovery from the Permian extinction, formations that essentially are “pavements built of thousands upon thousands of specimens of the characteristic Early Triassic scallop Claraia. . . . Despite the incredible abundance of some species, the total number of Early Triassic species is a tiny fraction of those alive only a few million years earlier or later.”  (p. 200-221)

Along the same lines is this observation by Peter Ward about fossil hunting in the Karoo,
For reasons still unfathomable, the lowest Triassic strata above the mass-extinction boundary are composed of red beds packed with fossils.  Almost all belong to a single species of mammal-like reptile – Lystrosaurus.  After the hard work of finding the very rare fossils in the youngest Permian beds, the fossils in these oldest Triassic beds were indeed a holiday.  There is an irony and mystery to this.  These beds were deposited soon after the mass extinction.  Yet the fossils – at least of this one species – are very common.  (p. 145)

(The fossil skeleton of the pig-sized Lystrosaurus hedini is shown above in a photograph by Rama, downloaded from Wikimedia and reproduced under the Creative Commons Attribution-Share Alike 2.0 France license.)

Ward suggests that perhaps this simply reflects that, in the post extinction period, conditions conducive to fossil formation were more prevalent.  But, significantly, he adds, “Or perhaps there were more animals – at least of this one single species.”  (p. 145)

In the midst of my immersion in the Permian extinction and its consequences, I happened to come across obituaries for botanist and ecologist Ruth Patrick (1907 – 2013), who died on September 23, 2013 (Julie Zausmer, Ruth Patrick, Ecology Pioneer, Dies at 105, The Washington Post, September 23, 2013; William Dicke, Ruth Patrick, a Pioneer in Science and Pollution Control Efforts, is Dead at 105, The New York Times, September 23, 2013.)

What a marvelous human being she was.  I am quite taken by her life story and scientific endeavors for many reasons.  One of them is the link, at least I think it’s a link or a connecting insight between Patrick’s signal contribution to science – the so-called Patrick Principle – and the aspect of the aftermath of the Permian mass extinction that I’ve just described – loss of taxonomic diversity.  In addition, a side of her life that I found particularly compelling was her relationship with her father.  I consider both of these topics below.

(This picture of Ruth Patrick is reproduced with the permission of the Ruth Patrick Science Education Center at The University of South Carolina Aiken.)

Patrick was a pioneer in many ways, not only as a woman breaking into the male-dominated scientific ranks in the 1930s and 1940s (talk about surviving in a hostile environment), but also as a botanist central to the modern development of the science of limnology (study of the ecology of rivers).

In 1934, largely because she was a woman and the Depression was in full swing, Patrick who was about to earn her doctorate from the University of Virginia could only find volunteer work at the Academy of Natural Sciences in Philadelphia.  In recounting her work experiences in science and at the Academy, Patrick was very matter of fact about the sex discrimination she encountered.  Not until 1945 did the Academy begin to pay her a salary.  In time, she established a department of limnology in the Academy, taught for many years at the University of Pennsylvania, published over 200 articles and several books, was elected to the National Academy of Sciences, and received the National Medal of Science, as well as the John and Alice Tyler Ecology Award.

She was a force to be reckoned with.  Her husband, entomologist Charles Hodge, once described his marriage as “like being married to the tail of a comet.”  It is clear in the 2004 WHYY TV show devoted to Patrick that, even at age 96, she remained youthfully passionate about science and about the role of women in the sciences.

Her key scientific contributions came from her study of diatoms (single celled algae), particularly her analysis of the relationship between water quality and the diversity of diatom communities in rivers.

(Photo on left is of Amphiprora alata (95 microns or 0.095 mm long); on right is Achnanthes frigida (no length given).  These images are from the Smithsonian Environmental Research Center's Phytoplankton Guide to the Chesapeake Bay and Other Regions.  They are used with permission of the Smithsonian.)

I do not pretend to know Patrick's work, reliant as I largely am on others’ descriptions, but it is widely asserted that Patrick was instrumental in a major shift in how water quality is analyzed, broadening it from a narrow focus on the presence of pollutants in the water to an appraisal of the diversity of the communities of organisms living in the water.  Her work on water pollution helped lead to enactment of the Clean Water Act.

Her conclusion that the diversity of species living within a fluvial environment reflects the overall health of this water is sufficiently profound that biologist Thomas E. Lovejoy has named it the Patrick Principle.  He writes,
In 1948 a line of research led by Ruth Patrick on freshwater communities in the United States (principally rivers) demonstrated that the number and variety of species reflected the natural physics and chemistry of a river as well as the stresses to which it was subject (e.g., pollution).  This work, which deserves to be recognised as the Patrick Principle, can be generalized to all kinds of biological communities, i.e., marine and terrestrial as well as freshwater.
Put differently, environmental stresses are all defined as problems because they affect living systems (not just humans).  So whether pollution, habitat destruction or climate change, they all impinge on biological diversity.  Consequently biological diversity is the ultimate integrator of environment change.  When that change is sufficiently intensive and extensive it leads to species extinction.  That, together with the scale and rate of the various kinds of environment change, conspires to create the biological diversity crisis.  (Biodiversity:  Threats and Challenges, in Biodiversity, Sustainability and Human Communities:  Protecting Beyond the Protected, edited by Tim O’Riordan and Susanne Stoll-Kleemann, 2002, p. 34. )
If I interpret the Patrick Principle properly, it’s that in times of environmental stress the diversity of the species that remain within the community is changed and impoverished.  Indeed, it’s possible that some of those that survive the stresses actually thrive.  Perhaps in the three decades since we were first introduced to the terms biological diversity and biodiversity we’ve become so familiar with them and their implications for our understanding of the environment that the Patrick Principle seems like a truism.  It shouldn’t be.

And then, at some point, I made what probably seems to be the pretty obvious connection between the aftermath of the Permian extinction and the Patrick Principle.  The consequences of environmental degradation documented in American rivers and streams by Patrick (the lessened diversity of life, not necessarily its absence) played out in the lowest Triassic – fewer species but, in some places, an abundance of individuals, like the Early Triassic scallop Claraia or the herbivore Lystrosaurus hedini.

Maybe it’s a prosaic insight, but it’s what I had.

There’s another aspect of Patrick’s life that I found particularly appealing – her unbridled admiration of her father.  (I suppose as a father, I’m inclined to make a big deal out of this.)  Her father, a lawyer, not only instilled a love of nature in Ruth and her sister, but also encouraged them to reject the traditional roles that females were expected to play in society, much to consternation of his wife.

Ruth recounted that her father “loved the natural world.”  (This and all subsequent quotations are from the WHYY show Hometown Legends:  Ruth Patrick cited earlier.)
Every Sunday afternoon, from the time I was five to about twelve, I would take a walk with him.  And we would always go to some woods.  Typically I would carry a basket.  And when I was little, of course I collected everything, worms, mushrooms, plants, and rocks, and everything and then we’d go home.  And my sister and I would have our milk and crackers, and, while we were eating and afterwards, Father would identify what we had in our baskets.  And, of course, we felt very proud if we could identify them and tell him what they were.
That her scientific pursuits had her mucking around in fields and streams did not sit well with her mother.  Even as her mother “felt girls should be in the home, not out in the fields, so to speak,” Patrick turned to her father and followed his advice, embracing science, academic pursuits, and the field.  In that day and age, she noted, “Ordinarily, [a] nice, healthy girl, just shouldn’t want to get a Ph.D.”  But, her father “believed that women could accomplish a good deal.  He used to say to me, ‘With your spare time, read, improve your mind.  You can hire people to wash dishes.’”

And, so, into her old age, Ruth Patrick remained focused on “trying to understand the natural world and to understand why we have the assortment of species we do have operating in our ecosystems and how can we protect them, how can we keep it happening.”

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