Monday, March 11, 2013

A Fossil As TARDIS

Doctor Who, the long running BBC science fiction series, features a marvelous creation at its core – a time traveling vehicle designed to blend in with the time and place to which it moves.  Two aspects of this time machine, known as the TARDIS (time and relative dimension in space), raise it to the level of sheer genius.  First, it suffers from a malfunction, regardless of where and when it arrives, it’s stuck in the form of an English police call box (think phone booth, if you’re old enough to remember phone booths) from 1963.  But, for me, the most powerful aspect of this conceit is that the TARDIS is much larger (indeed, approaching infinite) on the inside than it is on the outside.  Apparently, the bounded exterior dimensions are belied by different interior dimensions.  Thus, this call box offers the time traveler myriad rooms, a cricket pavilion, swimming pools, . . . .  (A quick guide to the TARDIS can be found on the Doctor Who homepage on the BBC website.  Despite loving the concept of the TARDIS, I must admit that I am not a Doctor Who devotee.)

The description of the TARDIS is necessary context for the fossil shell from the gastropod Ampullella parisiensis (d’Orbigny, 1850) shown below.  This gift from a friend dates from the Bartonian Age (40 to 37 million years ago) in the Eocene Epoch and was found in the Guepelle Formation, near Survilliers, northeast of Paris.  (It is just a little less than an inch in height (apex to aperture).)

Without question, this shell was a TARDIS.  Yes, it had traveled in time.  But that’s a prosaic claim in the face of what I discovered on the inside, where clearly other dimensions held sway.

As the picture below of the aperture shows, this fossil as I received it was filled with yellowish sand (and so much more).

After delicately extracting this matrix (roughly a 1/4th teaspoon’s worth), I began to explore this fill and an ever expanding Eocene world opened up before me.  Infinite?  Hardly, but, without question, the riches in these few pinches of material made the shell’s inside seem so much larger, so much deeper, than its outside.  (I would like to think that the material that, over the years, came to rest inside the shell is all Eocene in age, but I recognize that more recent or, perhaps even older, bits of stuff might have intruded, as well.)

It was evident from the outset that, amid the quartz fragments of the matrix, would be several “large” shells.  I separated these from the sandy matrix.  A few appear in the picture below.

Among the several gastropod shells is another, smaller Ampullella parisiensis (upper right in the picture above).  The glistening white, curved tube is, I believe, from some species of the gastropod Dentalium.  There are two shells from bivalves shown in the picture, one with a hole drilled into it by some miniature predator.  (My initial efforts to identify these shells has taken me to Cyril Baudouin’s fine website, which features fossil shells from France by geological period.  Unfortunately, most of mine don’t appear to be reflected in the Bartonian specimens he features.)

One of the two crab claw fragments in the mix is quite striking.

At the microscopic level, my horizons within this Ampullella parisiensis stretched and twisted.  There amid the bits of quartz I found my favorite microfossils – minute shells from foraminifera (protists) and ostracodes (crustaceans).  Though I’ve only just begun to work through this fill, several dozen forams have made an appearance, along with twenty or so ostracodes.  The adjective “fossiliferous” legitimately applies to this material.

By far, the most common of the forams in this material look like vertical, nested bits of braided twine.

This shape comes in several subtle variations (e.g., some have vertical striations, others are relatively smooth).  This broad group of forams, which dominates numerically among the forams I’ve found here, may be from the genus Massilina which dates back to the Eocene, though there are Massilina of much more recent vintage than that.

I haven’t made any headway identifying the ostracodes that tumbled out of the Ampullella.  A group of small, kidney bean-shaped specimens predominates.

I suspect I have more than one ostracode species or genus among those shown above, and, in all likelihood, have positioned some of them upside down.  (A method for conclusively determining the dorsal/ventral orientation of an ostracode shell is to examine the hinges on the interior of the shells because these animals’ shells are only hinged along the dorsal margin.  Unfortunately, I’ve pushed my microscope to its limits and the hinges remain out of visual reach.)

Finally, there was a moment as I worked through the material that filled the Ampullella parisiensis when I felt as though I’d been dropped into a fractal shape.  Perhaps this was not surprising, since fractals and the TARDIS both play with spatial dimensions.  Because it sets aside all of the complex mathematics that delineates a fractal, I like the definition offered at one point by the father of fractal geometry, Benoit Mandelbrot,

A fractal is a shape made of parts similar to the whole in some way.  (As quoted in Fractals by Jens Feder, 1988, p. 11.)

Self-similarity, a defining characteristic of fractals, is one of their most enticing, visual features.  As you examine a fractal shape at ever greater levels of magnification, patterns and forms repeat themselves.  You can literally get lost in a fractal shape, though familiar worlds reappear endlessly.  (There are many fractal generators available on the web that allow you to peer into ever small parts of this geometric space to find those repeating worlds.)

There was self-similarity in the Ampullella parisiensis shell.  When I began to empty the matrix from this shell, the tiny A. parisiensis shell emerged (seen in a photo above).  More to the point, this shell was filled with the yellow sandy matrix.  Wonderful repetition, one level in.  Unfortunately, I let the small shell’s contents mix with everything else on the sorting tray.  Perhaps even smaller shells had been hidden inside, perhaps ostracodes and forams fell out.  Certainly not an endless succession of ever smaller A. parisiensis shells with matrix, still, it was a wonderful hint of the fractal.

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