Wednesday, April 22, 2009


I shouldn’t be surprised that I bring the same strengths and weaknesses to two separate searches, even if those searches involve very different venues, tools, and quarry. You are who you are.

This is a tale of those two searches, one very modestly successful, the other unsuccessful. The sites are, one, a stream bed in suburban Maryland and, the other, principally the web. At the former, a stream cuts through the Severn Formation, a thin sandy layer punctuated by small quartz pebbles and chunks of gray phosphate and weakly populated with fish and reptile fossils. The Severn Formation is from the late Cretaceous, some 65 to 70 million years ago. At the latter site (the web), a tsunami of information crashes through all known boundaries creating a mess that often defies efforts to make sense of it.


I am particularly taken with fossil teeth from the shark genus Squalicorax, an extinct group of sharks known only with certainty from the Cretaceous (apparently this group did not survive the massive extinction at the end of the Cretaceous that did in the dinosaurs). Fossils from these sharks can be found in the Severn Formation. My attraction is based, I think, on their distinctive shape – crowns with a long convex mesial edge and, depending somewhat upon the species, a short, often straight, distal edge. The edges of the crowns are usually serrated (serrations are, to me, always a highlight in any tooth), and the height of the root relative to the crown can be impressive. This “drawing” of a Squalicorax kaupi nicely captures those attributes (5/8” on the slant).

The First Search

Half a dozen past searches along the stream site had rewarded me with a handful of small shark teeth and fish teeth, but never a fossil Squalicorax tooth. Over the course of these searches, I tried many searching techniques and strategies, from screening (shoveling gravel from gravel bars or the stream bottom into screens to separate the material) to just eyeing the steep banks of the stream looking for the tell-tale signs of the Severn layer. I have told myself (sometimes out loud) to be deliberate and methodical, but most times my lack of patience leads me to use a scattershot approach. I finally learned, though, that the best approach, for me, is surface collecting of the gravel bars that the stream creates, destroys, and recreates from one visit to the next. Unfortunately, the fruitful method of surface collecting here is tedious and painful requiring that I move on my knees along the gravel bars for several hours at a stretch. (At the Lee Creek Mine in North Carolina, this kind of hunting is called the “Pungo crawl” because you’re kneeling on Pungo River Formation material. Knee pads are standard equipment there.)

This past Saturday, I wandered up and down the stream, surface collecting on the gravel bars. Little stuff, fragments, enough to keep me interested and on my knees, but no Squalicorax. As I worked my way back to where the bank offers a gentle slope for climbing out of the stream, I came across some gravel and settled onto my knees for a final time. A little flake of material, black and white, caught my eye, as I picked it up, I recognized a tiny (1/4”) Squalicorax kaupi. I saluted it with a “Yes!”

Granted, it’s only a modest success given its size,very damaged root, and worn serrations. And it’s a curiosity with its strangely colored crown, half of it, including the tip, blanched white, presumably due to prolonged exposure, the other half the expected blue-black.

The Second Search

The second search sprang from the first. Though this find was my first at this particular site, I have found other Squalicorax elsewhere. Still, this one prompted a question. The Squalicorax are known as Crow sharks. Why?

The first step was easy. Do some Googling and (gasp) some shelf walking in my local public library. Shelf walking is the library research equivalent of surface collecting on a gravel bar – get yourself into a favorable location and begin scanning what’s there – similar aches and pains crop up. A lost art I’m afraid. Googling may have its parallel in screening.

This first step was productive – many sources attributed the common name to the scientific name of the genus, Squalicorax, and, more specifically, to the original name of the genus, Corax. This was the name given by Louis Agassiz back in the 1840s (volume III of his Recherches Sur Les Poissons Fossiles, a fundamental work in the paleontological study of sharks and other fish, cited elsewhere in postings on this blog).

Corax is Greek apparently for “raven” which, for fossil collectors, is, I guess, close enough to “crow” for that to be the common name. But, I didn’t think that really answered my question.

(One of the miscellaneous tidbits uncovered in this effort: Corvus corax is the scientific name for the common raven, according to the Dictionary of Birds of the United States by Joel Ellis Holloway and George Miksch Sutton, 2003.)

After lots of meandering through the web, my local library, and my small personal collection of books, I pieced some things together, but, as I ultimately concluded, not enough. This phase of any search can be disheartening. The expectation is that, just around the corner, is the answer. That’s much like a fossil hunt which often stretches into the dusk because that prize specimen is always just around the corner. This phase involves lots of retracing of old ground – the marks of your passage are everywhere, but still, maybe you missed something.

I tried to address the early signs of trouble – the renaming of the genus needed some exploration. The best place to start (and often end) when you’re researching the taxonomic history of an ancient organism is the Paleobiology Database. That source made it clear that the change in genus names occurred in 1939 and the instigator was someone named Whitley.

Well, turns out that, in a 1939 article, ichthyologist G.P. Whitley renamed the genus Squalicorax. Depending upon your source, Squalus is Latin for “fish” or, more to the point, “shark.” Why Whitley felt compelled to do that is still a mystery to me because the article in question isn’t on the web (we're not quite to the point where all of the world’s knowledge is available at your fingertips – yes, there's lots available, particularly if you have an institutional affiliation or money).

Even worse, there seems to be a bit of citation sloppiness on the web (certainly no surprise there) and in scientific journals (a bit of a surprise there) about where he actually made the name change. For example, in an otherwise very informative article entitled “The Oldest Record of the Late Cretaceous Anacoracid Shark, Squalicorax Pristodontus (Agassiz), From the Western Interior, With Comments of Squalicorax Phylogeny” (New Mexico Museum of Natural History and Science Bulletin), authors Shimada and Cicimurri note that Whitley named the genus Squalicorax in 1939. Their reference? An article they attributed to a 1939 issue of the Australian Journal of Zoology. Unfortunately, that journal began publication in 1953. They have the wrong publication. Seems Whitley published his article renaming the genus in the Australian Zoologist, a publication of the Royal Zoological Society of New South Wales (which, incidentally annually awards the Whitley Prize in honor of Gilbert Whitley for “outstanding publications . . . that contain a significant amount of information relating to the fauna of the Australian region").

It’s not a big deal, I guess, but it’s disheartening. Had I wasted lots of time searching for a 1939 article from the Australian Journal of Zoology when the actual piece was readily available that would have been a bitter pill to swallow. The actual article, as much as my ham handed repetitive searching on the web can prove, isn’t available electronically. So, I’ve gone a different route and made an online OCLC request for an interlibrary loan (or, actually, a photocopy) of the article. I don’t know what I will find, but that’s the beauty and the frustration of the search.

The Shimada/Cicimurri citation error is duplicated in other pieces they’ve published and on websites. For example, Mike Everhart has a nice piece on “Large Sharks in the Western Interior Seas” that covers Squalicorax falcatus, and perpetuates the erroneous citation.


But, none of this actually gets at my underlying question. The translation of Corax may account for the common name used now, but that’s missing the point. Why was the word corax used in the first place in naming this group of sharks? That is, what prompted that link between “raven” (or “crow”) and these sharks back in the early 19th century? I don’t know and, as far as I can tell, Agassiz isn’t talking on the web or elsewhere.

Wednesday, April 15, 2009

A Day at the Beach -- Speak Memory

An exercise in memory.

A sunny, warm afternoon in early April on the beach at Fort Lauderdale, this is time well spent, not thinking about the befores or the afters, just sifting idly through the shell debris marking the reach of the tide.

Well, not completely idly. I have this thought – there have to be many sharks cruising off the Florida coast, losing their teeth by the thousands in the course of a lifetime. Despite most of these teeth being lost to the ocean depths, I have to believe some of these modern teeth will wash ashore and hide among the white fragments of shells. Though I do have this goal (still totally unrealized), I am not unaware that other things of interest are hidden here. For one, this erratically coiled, patterned tube, white and yellowish, clearly a shell.

Big, colorful, classically beautiful, complete shells – that’s been the extent of my interest in shells. This is small, inconspicuous, pale, and vaguely scatological. Maybe that last attribute explains why I pocket it (later leaving it on a bureau in the house where I stayed).

With some very desultory research, I conclude this is a worm shell, a shell from a gastropod. I tentatively label it as a Florida Worm Shell (Petaloconchus floridanus) or perhaps an Erect Worm Shell (Petaloconchus erectus). Or, maybe, the correct answer is “none of the above” but I don’t think so.

It took a couple of days, but, drifting out of some opened mental drawer, came a memory of an another object resembling this shell, an object I had not only seen before, but had collected as a marine fossil. “Out of sight, out of mind” is total rubbish if memory is part of the mind. Sure, the memory can be an unreliable guide to what you’ve seen. Sometimes establishing links that aren’t really there. “Yes, yes, that’s just like . . . .” And upon seeing the source of that memory, murmuring, “Oh, never mind.” But, “out of sight” has no bearing on what’s happening in the memory.

Here’s the basis of unbidden memory.

Some 18 months ago, while sifting through some of the fossiliferous material from the Lee Creek Mine piled up in front of the Aurora Fossil Museum (Aurora, NC), this curiosity with its patterned, coiled tubing, showed up, was put into its own baggie, and inserted in a drawer labeled Aurora. Now, another tentative identification. This, I think, is also a worm shell, though fossilized, perhaps a Serpulorbis granifera.

As is usually the case with me, there is some issue with the ID. S. granifera is clearly found in late Pliocene (Chowan River) and early Pleistocene (James City) formations (roughly 1 to 3 million years ago) at Lee Creek. Does it go back farther than that? It’s important, because I thought I was working in material from the Pungo River Formation (mid-Miocene – 10 to 20 million years ago).

Perhaps, this specimen was reworked from its original formation.

Sort of like a memory that turns up where and when you least expect it.

Coda: I am puzzled by the process through which the worm shell became fossilized. The fossilized tube is hollow in spots. Why didn’t it fill completely and the intruding material solidify? Perhaps it did, but now some of the solidified material has crumbled and fallen out as the exposed fossil encountered the elements.

Identification note: The identification of the fossil as Serpulorbis granifera is based on plate 35 in Geology and Paleontology of the Lee Creek Mine, North Carolina, Volume II published in the Smithsonian Contributions to Paleobiology series). I was let down by Moore’s Invertebrate Fossils, finding nothing in it coming close.

Sunday, April 5, 2009

Paleontology in Space (or Dinosaur Bones on the Moon)

Ira Flatow moderated an interesting discussion on Science Friday this past Friday (second hour of the show broadcast on National Public Radio on April 3, 2009). The subject was the prospect of, and search for, life elsewhere in the universe. His guests included some of the leading lights in the world of astrobiology: Peter Ward (paleontologist, University of Washington); Paul Davies (cosmologist, physicist, and astrobiologist, and director of Beyond: Center for Fundamental Concepts in Science, Arizona State University); Baruch (“Barry”) Blumberg (medical doctor, biochemist, anthropologist . . . so hard to know how to characterize this polymath, a 1976 Nobel Prize winner in the field of medicine or physiology – to give one affiliation, he’s distinguished scientist in NASA’s Astrobiology Institute), and Ariel Anbar (biogeochemist – yes, that’s the label he applies to himself, Arizona State University and principal investigator at the NASA Astrobiology Institute).

Paleontology had a small role in the discussion, much smaller than I would have liked. Still, there were tantalizing glimpses of its role in astrobiology. Peter Ward, the paleontologist in the group and someone who has been studying mass extinctions on Earth, observed that geology and paleontology offer us the opportunity to recognize the forces that threatened life in the past and that could do so once again in the future. Offering a more positive spin on this look into the past, Ariel Anbar, the biogeochemist, asserted that the geological record provides “alternative versions of Earth” in which life existed under very different conditions from today, one avenue for important insights into the prospect of life existing elsewhere in the universe under extreme conditions.

There was some discussion of the discovery of methane in the present day Martian atmosphere which suggested the possibility of microbes at work. Ward commented that this was good news because it might encourage more exploration, though it wasn’t quite along the lines that he’d been advocating because, as he put it, “I always thought that the best shot for Mars would be a paleontologist first on the surface looking for fossil life.” Yes.

As the group considered the ways in which life could be spread within planetary systems and possibly further afield in the universe, there was discussion of the ejection of matter from Earth into space during the heavy bombardment of the Earth by cometary and asteroidal material early in its existence, and through the more infrequent impacts later. Ward (I'm nearly positive he was one speaking at the time) observed that the asteroid that crashed into the Earth 65 million years ago threw up lots of material from Earth. He noted, perhaps with a smile on his face (hard to tell on the radio), that it’s “not inconceivable we have dinosaur bones on the Moon.”

Coda – A Few Random Notes

I don’t know if Science Friday is an acquired taste. On occasion it’s a frustrating experience for me, particularly when the topics seem to have little connection to science. This time, the topics were wonderful. Of course, Ira Flatow was his usual self – sometimes asking interesting questions, sometimes not, sometimes fumbling with the ones he asked, sometimes letting a discussion run its appropriate distance, sometimes cutting it short too soon. As an aside, in the mental image I create when I listen to him on the radio, I invariable picture Alan Alda (their voices are nearly identical).

I cannot end without returning to the Brooklyn-born Barry Blumberg. His brief autobiography, prepared for the Nobel Prize Committee (updated through 2006), chronicles an inspiring life, one marked by a dedication to science, education, and service. All of it apparently underlain by a wonderful sense of humor. Among other surprising aspects of that life is that for a time he was the Master of Balliol College, Oxford University. Finally, I cannot resist – at some unknown date (the webpage isn’t helpful on this), he was a guest on the BBC program entitled Desert Island Discs. His choice of music to have on a desert island? Blew me away.

1. ‘Space Oddity’ performed by David Bowie
2. ‘California Dreamin’ performed by the Mamas and Papas
3. ‘City of New Orleans’ performed by Willie Nelson
4. ‘Take the A Train’ performed by Duke Ellington and Orchestra
5. ‘Nimrod’ from Enigma Variations composed by Elgar and performed by the London Symphony Orchestra, conducted by Sir Colin Davis
6. ‘When Johnny Comes Marching Home’ performed by the Philadelphia Orchestra & the Great Mormon Tabernacle Choir
7. ‘Flowers of the Forest’ performed by The Celtic Tradition
8. ‘The Aria of Bach’s Goldberg Variations’ performed by Charles Rosen

Wednesday, April 1, 2009

Sand Tigering – Making Subtle Distinctions Can Be Such A Hassle

Exchange between Paul Farmer (Harvard medical doctor, infectious disease expert, anthropologist, and MacArthur genius award winner) and an elderly Haitian TB patient.

This woman, who had followed the prescribed medical regime and been cured of TB, tells Farmer that she believes her TB was inflicted on her by someone’s sorcery.

Farmer finds this startling. If she believes that sorcery was behind her TB, why did she take her meds?

With a smile, she responds, “Honey, are you incapable of complexity?”

(Based on a passage in Mountains Beyond Mountains: The Quest of Dr. Paul Farmer, a Man Who Would Cure the World, Tracy Kidder’s marvelous book published in 2003.)

Farmer saw this as an example of how people often hold contradictory views simultaneously. Sure, many people do that, often unthinkingly, and they are frequently incapable of seeing the contradictions. But, it seems to me that the elderly TB patient’s comment revealed something more. Where Farmer saw contradictions, she didn’t. Her view was more subtle than that. She recognized that the world isn’t black or white, there is truth to be found in many places, even in opinions or belief systems that may seem totally incompatible or contradictory.

Pity the Poor Sand Tiger Shark

Which leads me to the poor sand tiger shark. There’s a standard picture posted on the web by amateur collectors following a hunt for fossil shark teeth. Several large or rare teeth prominently occupy space in the picture – each carefully placed to stand out. But, to one side of the picture will be a chaotic lump of teeth, seemingly spilled in haste. The teeth in that lump are more likely than not from sand tigers.

Why? Because distinguishing among sand tiger species is hard work. It can be excruciatingly difficult with many species in the fossil record often differing in marginal ways. In the Chesapeake Bay area, for instance, fossil teeth are found from some 15 different sand tiger species spread among 4 different genera. (Bretton Kent, Fossil Sharks of the Chesapeake Bay Region, 1994)

Sand Tigering

From that practice with teeth, I’ve added a verb to my patois. Creating an indistinguishable lump of anything because the differences among its component parts are hard to identify, and then slapping a crude label on it, is sand tigering. We all do it. It’s so much easier to sand tiger than to draw careful, fine distinctions and run the risk of discovering truth where we didn’t expect, or want, to find it.

Sand tigering seems to be done with some greater intensity these days. In fact, in these stressful times, there’s Olympic-class sand tigering going on – for example, corporate bonuses (myriad practices lumped together, all bad), Republicans (all Rush Limbaugh), or government intervention in the economy (socialism). Hey, I'll admit that I sand tigered opponents of the Paleontological Resources Preservation law (an anti-government selfish cohort).

In light of all of this, there’s one question that each of us needs to answer:

“Honey, are you incapable of complexity?”
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