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the great fossil enigma

17 december 2013

Before reading Simon Knell's Great Fossil Enigma, it would be helpful to know a bit about conodonts. Knell throws the reader into the middle of 19th-century conodont debates without much exposition or description or definition: we pretty much get our first glimpse of the little things as their first observers saw them, sketchily, through a microscope, and then we're immediately into arcane controversies.

Fortunately I knew a bit about conodonts from reading and re-reading Stephen Jay Gould's wonderful book Wonderful Life. But the mysteries of the conodont were just being clarified when Wonderful Life appeared in the late 1980s, and Gould has little definitive to say about them. I'd remembered the little guys ever since, though, as one of the oddest of paleontological oddities: extremely minute fossil structures that look like teeth but aren't much like any known teeth, so small that several (as in Knell's opening illustration) can fit on the head of a pin.

What the heck are conodonts? As Knell shows, for a long time after their discovery over 150 years ago by the Baltic paleontologist Christian Pander, people didn't really care very much. One principle of animal studies is that the public is only interested in "charismatic megafauna" like pandas or Tyrannosaurus Rex. Conodonts are charismatic, but they are also microscopic, so popular interest was nil. Pander thought they were the teeth of fish; Richard Owen guessed that they might be the claws of crabs; some thought they were the teeth of worms, and a few thought they were the teeth of snails. Some thought they were the substructure of tentacles or other bizarre bits of weird animals. A few thought they might be plants. Many others thought that such thoughts were idle.

A lot of people studied conodonts over the ensuing century, though, because they are ubiquitous in Paleozoic and Triassic rocks, and can be used to identify strata that might bear oil, a much less ubiquitous commodity. A whole generation of conodont experts was trained in the United States during the oil-boom years between 1900 and 1960, without giving much thought to what the conodont animal might have looked like or how it might have behaved. As long as the fossils of myriad conodont bits aided oil exploration, the bits were an end in themselves. Knell shows how this became a problem in naming: most fossil species get biological names much like living species, but conodontists were tempted just to name parts of what they knew must have been larger animals. Confusion was the best state of affairs for most of the 20th century.

What all the "conodont workers" needed were fossils that preserved soft parts of the "conodont animal," but they didn't have any. The cleverest among them noticed that conodont elements tended to appear in statistically predictable combinations, sometimes in "assemblages" that were clearly the hard remains of decayed soft-bodied creatures. That didn't help clarify whether those creatures were fish or worms or whatever, but it was the basis for inferring actual biological species instead of just bits and pieces.

Two fossil discoveries marked watersheds in conodont science. First, around 1970, some researchers found in Montana a few soft-tissue fossils that included hard conodont elements. Debate raged over whether these little guys, who indeed looked like worms, were conodont animals. Some thought that they were the remains of what Knell keeps oddly referring to as "the animal that ate the conodont animal," as if this meal only happened once in hundreds of millions of years. Then, in the early 1980s, fossils from Scotland were found to contain what must be the actual conodont animal: almost certainly a chordate, and very likely a vertebrate as well. Possibly a human ancestor, if your patience with genealogy goes back 500 million years. (As so often happens, the Scottish conodont animal was first noticed not by a fieldworker with a whiskbroom but by somebody nosing around in museum drawers and finding rocks first collected in the 1910s.)

Knell deliberately underplays the dramatic potential of this long paleontological quest. This is not a tale of heroic fossil wranglers braving the Gobi Desert. Basically, The Great Fossil Enigma is the mother of all literature reviews. Knell is not a scientist and is careful not to argue for specific interpretations of fossils. He is a historian (of culture, science, academic life, and museums), and his interests lie in seeing how people make meaning out of the collections that they treasure most.

The Great Fossil Enigma is a book based consciously on an inherent irony. Knell notes that previous booklength surveys of conodont studies have been dated, indeed obsolete, pretty much as soon as they appeared. This includes Walt Sweet's 1988 volume The Conodonta, but also Gould's Wonderful Life. Both books, Knell argues, artificially fixed an ephemeral and ever-changing picture. Anyone seeking a current understanding of conodonts (or of the Burgess Shale, the subject of Gould's book) would be led astray even while reading the first copies of such a book hot off the press.

As vehicles by which progress is made, [books] have the unfortunate effect of producing a freeze-frame image that is then left to drift into the future, giving the illusion of still being current. The scientific book is an impossibility; almost immediately it is a history book. (322)
And so Knell has chosen, wisely, to write a history book.

Knell's theoretical positions come out most clearly in his most interesting chapter, an epilogue called "The Progress of Tiny Things." He starts with an observation by Sweet: that only fossils are facts; "anything other than these few material facts was contestable" (361).

The fossils that existed within the minds of the conodont workers were different from those preserved in stone. Indeed, the fossil that participates in science is only ever a conceptual or immaterial one: a fossil imagined and believed and not the one that has been hewn, boiled, or dissolved out of the rock. To make use of the material fossil, science must interpret it. (361-62)
Fossils don't deliver "sermons in stones." But the realities of academic culture make scientists behave as if they did. Even if you know that next week's sermon will contradict this week's, you can only contribute to scientific discourse by drawing up comprehensive theories and making dogmatic claims. Humility like Sweet's in the face of enigmatic evidence is the exception. Time and again, scientific writers quoted by Knell make the most sweeping claims (which are swept away by competing claims about the next new fossil). Dogma is hardly unknown, despite the common assumption that scientists and dogmatists are enemies. Australian expert Sue Turner is quoted by one of Knell's sources as saying that "'no evidence we could ever provide' would convince her that conodonts were vertebrates" (342).

Knell's implication is hardly that all reality is socially constructed. There are, after all, those fossils. Every day when I brush my teeth I look up at a shelf where a fossil fish stares back at me from millions of years ago. It's a fact. And it's a fish; if it weren't petrified, it would be just as acceptable for dinner as a nice rainbow trout. Human constructions most need to be invoked when a fossil, like the conodont, doesn't fit beyond a reasonable doubt into the real-enough category "fish." Christian Pander, the conodont's discoverer, thought it was a fish. In 2013, most observers who aren't dogmatic holdouts think again that it's a kind of proto-fish, at least. But for much of the intervening 150+ years, the conodont was, for all that anybody knew, a worm, a snail, a crab, a plant, or as Gould might have preferred, an "oddball." Maybe by 2063 it will be something else altogether.

Knell, Simon J. The Great Fossil Enigma: The search for the conodont animal. Bloomington: Indiana University Press, 2013.