Monday, April 18, 2011

That's Not What I Expected ~ From Fake Cows to Edestus Sharks


In the following passage from Act V, Scene iv of Shakespeare's The Two Gentlemen of Verona, the "page" in question is fair Julia dressed as a boy.

  Valentine. And as we walk along, I dare be bold
With our discourse to make your Grace to smile.
What think you of this page, my lord?
  Duke. I think the boy hath grace in him; he blushes.
  Valentine. I warrant you, my lord, more grace than boy.
  Duke. What mean you by that saying?
  Valentine. Please you, I’ll tell you as we pass along,
That you will wonder what hath fortuned.


The Duke registered the visual cues of Julia's disguise and so assumed the page was male.  Sensory signals and language coupled with past experience build our expectations and, for the most part, we get it right.  But there are those moments when reality surprises – “Whoa, that’s not what I expected.”

This is a posting about not seeing things coming, about when reality messes with expectations.  It begins with dogs.  Paleontologist Alton Dooley recently wrote on his blog about how his dog mistook a straw-filled wire frame shaped like a cow for the real thing.  Her mental algorithm posited cow from everything seen and she reacted accordingly, that is, until her sense of smell kicked in.  As Dooley described the process,
Hypothesis: Based on visual observations, I think that’s a cow. If it is a cow, it should smell like a cow. (Null hypothesis: It’s not a cow.)
Procedure: Sniff to see if it smells like a cow.
Result: It doesn’t smell like a cow.
Conclusion: It’s not a cow (the null hypothesis is not rejected).
(Dooley's assessment of this thought process:  “My dog is a scientist!”)

Shortly after I read Dooley’s posting, an AP newswire piece caught my attention.  Run in the Washington Post (April 10, 2011) under the title “Miner Finds 300-Million-Year-Old Fossil, it described the “shark jawbone” believed to come from an Edestus shark which a Kentucky miner found a couple of months ago.

The Expectations

My expectations-generating facility kicked in, conjuring images of miners and shark teeth.  The photo below of a Pennsylvania miner in 1940 captures the essence of the “miner visual/mental template” that I created when I read the word “miner.”  (Sources for all photos are provided at the end of this posting.)

Shark teeth?  The Carcharocles megalodon teeth shown below, though much younger than the Edestus fossil mentioned in the article (roughly 4 million years old from the Pliocene Epoch, compared to the some 300 million years old for the Edestus from the Carboniferous Era) reflect what first came to my mind when I read of fossil shark teeth.


The Reality

My expectation were dashed – I was wrong on both counts, miner and fossil.  My stereotypic view of miners arises from having seen countless photographs just like the one above.  Yes, my image of a miner is defined, fairly or unfairly, by the anticipated visible impact of the job, though mining is a job that more than most may well define the person.

As for the fossil, had I been more experienced, the weirdness of truly ancient sharks, such as Edestus, would have shaped my expectations.

An article that ran in the online University of Kentucky News about the Edestus fossil (which is on display at the university) carried the images that brought me face to face with the unexpected.  (Ancient Shark Fossil Found in Western Kentucky Mine, April 5, 2011.)  Here, then, are the miner and the fossil.



Very surprising.  A new image for me of a miner.  But, even more remarkable, a wonderfully different vision of shark teeth, though not so much for individual teeth, but for the whole assemblage.  These are clearly associated teeth (i.e., coming from a single individual), all rooted in what would certainly appear to be a “jawbone” (more on that later)  The entire fossil measures about 18 inches, and the crown of the largest of the serrated teeth stands more than 2 inches tall.

Responding to the unexpected, I learned a bit more about the miner and a fair amount more about the shark.

First, the shark.  Joe Cōcke, in Fossil Shark Teeth of the World (2002), identified Edestus as bearing the common name of the “coal shark” – very apt given where fossils from this shark appear to be typically found, deep underground in coal mines.  Interestingly, they turn up slightly separated from the seam of coal – makes sense since I have to assume they lived in a marine environment different from the one of heavy vegetation that became coal.  In this instance, the miner found it four miles into the mine shaft and some eight inches above the seam.  The Kentucky Geological Survey has described a couple of other Edestus fossils which turned up in similar proximity to coal seams.

Cōcke noted that Edestus teeth formed an “arch” in the shark’s jaw (the curved line along which the teeth are arrayed shows up clearly in the photo above).  The Edestus is one of several different edestoid sharks whose teeth have puzzled scientists and have led to truly bizarre hypotheses about their arrangement in the fish.  Because the teeth appear to be a single file, many have theorized that they are symphyseal – arising where the right and left sides of a jaw meet in the front of the mouth and extending out from the mouth.  An Edestus find described in 1912 by Hay (On an Important Specimen of Edestus; With Description of a New Species, Edestus Mirus, by Oliver Perry Hay, Proceedings of the U.S. National Museum, Vol. 42, No. 1884, 1912 ) (see photograph below) suggests why the fish earned the nickname “scissor-toothed shark.”


The “tooth-bearing shafts,” as they were described in the article, line up like the two halves of a pair of pinking shears.  Hay concluded,
The sharks that belonged to the genus Edestus must have presented a singular appearance with their straight or bent tooth shafts protruding from their mouths . . . . (p. 37)
Here’s a drawing of one interpretation of the evidence which Hay might well have endorsed.  Truly bizarre (and probably not accurate).


Edestus is but one of the edestoid sharks.  The Helicoprion offers a more extreme configuration of teeth in these kinds of shark – a tightly drawn spiral of teeth.


The various reconstructions of how these Helicoprion teeth might actually have been arranged in the living shark stretch the imagination.

I fear that these reconstructions actually do become fantastical.  In The Orthodonty of Helicoprion, Smithsonian paleontologist Robert W. Purdy has laid out the justification for a different and, to my mind, more rational (though still strange) Helicoprion dentition.  He considered such issues as the different rate of tooth replacement among Paleozoic sharks, wear on teeth, and the effects on the shark's hydrodynamics of a protruding spiral of teeth.  This different reconstruction focused on the branchial or gill-related region of the shark’s body and concluded that the spiral dentition belonged in the throat and served to “move the [shark’s] prey toward the esophagus.  This type of dentition would work well for catching soft-bodied prey.”  Purdy and other Smithsonian scientists advised artist Mary Parrish as she illustrated this different view of Helicoprion.  Purdy’s article includes Parrish’s illustration as does the Smithsonian’s Ocean Portal website.  If I receive permission to post it, I will.  Look closely at her painting, the top of the spiral is just visible inside the shark’s mouth.

I’m not sure exactly how Edestus would be reconstructed under Purdy’s analytical framework, but I suspect it would be closer to reality than the drawing above.  Regardless, Edestus was certainly not what I expected.

As for the reference to the “jawbone” in this shark, it doesn’t withstand scrutiny.  Sharks are chondrichthyans (from the Greek for cartilage fish) so no true bone in their bodies, even way back then.  Each Edestus tooth had a very long root, sharply angled back.  The so-called “jawbone” or “tooth-bearing shafts” as Hay called them are thought to be those fossilized roots.  Images of Edestus fossils on the Kentucky Geological Survey’s website (scroll down to the Pennsylvanian-age shark fossils) more clearly show these individual roots lying together.

And finally, what about the miner?  From the University of Kentucky piece, we learn that the young miner found the Edestus fossil on February 24, 2011 and that subsequently the mine company allowed him to keep it.  Further, the miner “has agreed to let [Jerry] Weisenfluh [associate director of the Kentucky Geological Survey] bring the jawbone back to KGS at the University of Kentucky to be examined more closely by researchers at KGS and UK’s Department of Earth and Environmental Sciences.”  The article concluded by noting the miner “plans to keep watch for more fossils in the mine.”

Now, that's unexpected, a heartwarming fossil-related story where everyone apparently behaved civilly.  Most encouraging, the miner embraced his role in helping to advance science.

Unfortunately, I then read an ABC news story from April 11, 2011, and it seems that even here the seamy side of fossil collecting had been exposed.  The miner, according to ABC news, said that collectors had contacted him looking to purchase the fossil, though apparently he had not yet made up his mind about what to do with it.  He was quoted as saying, “I could sell it. . . .  There are so many options.”

Nasty people those collectors, introducing a monetary component to this.

Though perhaps that’s not really where the idea of capitalizing on this actually arose.  I found a message posted on March 6th on the online Fossil Forum suggesting that the mercenary aspect of this saga might have originated remarkably early.  Easy to tie this message to the miner since the fossil shown in the photo displayed below the message on the Forum is clearly the same one that has just now attracted news coverage.  (I’ve reproduced the message just as it appeared.)
I'm told this is from an edestus shark ... whats something like this worth? I found it in a western ky coal mine and Ky Geological blah blah wants to display it on a yr or two loan. try to figure out if i should risk loaning it, any info would be helpful.
Yes, the message raises a legitimate concern about the risks of letting the fossil go out on loan, but I’m struck by the crassness of its opening move – “whats something like this worth?”  That’s cutting to the chase.  And then there’s the snarky reference to the Kentucky Geological Survey as “Ky Geological blah blah.”    Perhaps all's not well in the land where scientist and lay person join forces.

Is this closer to what I expected?  Let's just say I'm not surprised there's some tension here.


Sources of Photos and Images
1) The first coal miner photograph is from the Library of Congress and was taken by Jack Delano, August, 1940.  It is titled Miner at Dougherty's mine, near Falls Creek, Pennsylvania.
2) I took the photograph of megalodon teeth in the Aurora Fossil Museum, Aurora, North Carolina.
3) The pictures of the contemporary miner and his Edestus fossil are reproduced with permission of the University of Kentucky.  Mike Lynch of the Kentucky Geological Survey (affiliated with the University of Kentucky) wrote the article and took the photos.
4) I copied the photograph of the two files of Edestus teeth from Hay's 1912 article.
5) The illustration of Edestus is from Wikipedia Commons, created by Dmitry Bogdanov.  It is licensed under the Creative Commons Attribution 3.0 Unported license.
6) The Helicoprion fossil is from the Smithsonian Institution and was collected by W. W. Rubey in 1942.  It is USNM number V22577.
7) The fanciful reconstruction of Helicoprion is from Wikipedia Commons, created by Dmitry Bogdanov.  This file is licensed under the Creative Commons Attribution 3.0 Unported license.

2 comments:

  1. "...I’m struck by the crassness of its opening move – 'whats something like this worth?'..."

    Not too surprising, really, when you consider that most members of the general public probably see "old stuff" through the filter of Antiques Roadshow, where the bottom line is always "How Much is it Worth?". As a geologist with a palaeontological bent, I frequently get people showing me things they've found. Question #1 is always "What is it?", Question #2 is "How Old is it?" and Question #3 is inevitably "What's it worth?".

    Cheers,
    --Howard

    ReplyDelete
  2. Perhaps it was always so. Guess I hoped that wouldn't be the case in this instance.

    ReplyDelete

 
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