The Flight of the Iguana (21 page)

For hundreds of years the shale has been quarried also for decorative rock. Today that commercial quarrying continues, at a handful of sites around Holzmaden, with tools and methods nearly unchanged over the past century. Now you might see a dump truck or a power shovel helping to move shattered rock, but the delicate labor of prying up large sheets of shale, unbroken, suitable for paving the floor of a den or the wall of a fireplace, is still done by workmen using crowbars and picks. Occasionally one of those workmen will lift a slab and notice a brownish shape in the blue-gray shale—the hint of a fossil embedded there. Setting that slab aside, the workman will send a message to Herr Hauff, who will hurry out to the site. Other slabs will be pried up and inspected. The ideal is to capture a whole animal within just a few large pieces, then get those pieces back to the workshop and fit them together like a puzzle. Once that matrix is reassembled, the shale is chiseled and etched away—mainly again using hand tools, the fine finishing done with dental picks under a microscope—to liberate the fossil. For ninety years one Hauff or another has been responding to those messages from the quarries.

But the fossils have never been more than a by-product of Holzmaden quarrying. Nowadays, as in the past, it is not economically feasible to work the quarries purely for fossils. In this particular age, with humans and not reptiles dominating the Earth, raw fireplace stone carries more value than raw ichthyosaurs.

Once the Hauff craftsmen have intervened, of course, that balance tips. Museum Hauff is a private institution that supports itself largely through the sale of specimens, and a fully prepared ichthyosaur might bring $20,000. The customers are other museums (for specimens with unique scientific significance), as well as large corporations and private collectors (for decorative specimens with less scientific value), and this cottage industry allows the Hauff operation to remain independent, an old-fashioned
family-run exercise in crazy devotion and pride. In this combined dedication to craftsmanship, private enterprise, and science, they seem like a cross between Harry Winston and the Leakeys.

The commercial Holzmaden stone comes from one particular layer of those Jurassic marine sediments, twenty feet below ground level and just seven inches thick. This buried seven-inch layer, which splits nicely and has an attractive surface, is what drives the quarry economy. The strata that are broken and pried out to reach that layer are cast aside as scrap—but from among that scrap, rescued from power shovel and dump truck, come the ancient reptiles. Paleontologists all over the planet know those fossil-rich Holzmaden strata as the “Middle Epsilon” division of the Black Jurassic period, and the slightly less formal label in German is “Posidonien-schiefer.” To you or to me: the Poseidon Shales. A sea god's gift to posterity. Go to a good science museum in Stuttgart or Tübingen, or for that matter in Paris, Berlin, Cambridge, New York, and wherever you find ichthyosaurs you will probably also find a small plate saying, “Middle Epsilon, Black Jurassic. Holzmaden.” Or perhaps only “Posidonien-schiefer.” You may also see the name Hauff. Most of those specimens have passed through the family workshop.

But the Poseidon Shales are famous not only for ichthyosaurs. They have yielded a whole menagerie of marine life from the Jurassic period, and the walls of Museum Hauff display that life as a great stonework frieze, a portrait of the offshore community as it existed 160 million years before Christ. Besides ichthyosaurs there are two other seagoing reptiles, the plesiosaurs (resembling giant long-necked turtles, but without shells) and the steneosaurs (similar to the fish-eating gharials that survive in India and Nepal); there are also pterosaurs, those delicate flying reptiles, which sometimes died at sea and sunk to their graves in the underwater mud; and a selection of garish invertebrates, including the sea lilies (plant-like creatures with long stems and flowery heads, which were actually animals related to starfish) and the
ammonites (a group of spiral-shelled mollusks that disappeared at the same time as the dinosaurs). All of these life forms—the giant and the small, the delicate and the robust, the predaceous and the benign—have been preserved in stunning detail by the gentle embrace of those Jurassic marine muds, and brought back to light by the methodical scraping of Hauff chisels.

One wall of the museum is filled by a huge panel of sea lilies, a parquetry of gray slabs stretching from the floor to a peaked roof fifty feet up, upon which a colony of these bizarre animals are frozen in ropey entanglement, like an orgy of giant sea worms with sunflower heads. This amazing thing turned up in a quarry back in 1908. For forty years it remained in the raw state, locked inside chunks of shale. The Hauff craftsmen began work on it, finally, in the 1950s. By then old Bernhard Hauff, the grandfather and founder, was dead. Fifteen years later, the sea lily panel was finished. Now it hangs here majestically, the largest community of fossil invertebrates exhibited anywhere in the world.

On the wall just opposite hangs an oil portrait of Bernhard Hauff. He seems, as always, to be taking the long view. Dreaming the dream of time.

This museum itself is a private dream, a heartfelt and heritable whimsy, that exists to amuse and to edify the public. It expresses one family's quixotic conviction: that the history of life on our planet is not only intriguing but beautiful, a miracle that belongs to everyone.

“So, you will find nearly nowhere on the world where you can take out information and fossils like we have it here in Holzmaden,” Herr Hauff tells the American teenagers. He has not exaggerated. He smiles. The students have listened and stared at his fossils for nearly an hour, a great feat of prolonged attention, and Herr Hauff knows he dare not try to hold them five minutes longer. He pushes his hands into the pockets of his jeans, and shrugs. He is an optimist. He believes that one or two of them will remember.

Genetics and Aesthetics in the Life of a Dashing Animal

Beauty is one of the lies we live by. The joys of success is another. God knows, we have been offered enough minacious parables over the centuries to discourage both of these stubborn delusions—from
The Iliad
and
Oedipus Rex
to
The Picture of Dorian Gray
and “Richard Cory”—but still they survive, eternal inverities. Evidently we need them at least as much as we need mere truth. The latest increment of counterevidence against that pair of sleek cheery falsehoods came and went recently as an article in the journal
Science,
and unless you were watching closely, you may have missed it.

Based on the experimental work of a team led by S. J. O'Brien, a geneticist from the National Cancer Institute, this article presents a technical assessment of the unusually low genetic diversity within a certain species. O'Brien's study is noteworthy to a broad audience not so much because of its results (“we found a total absence of genetic polymorphism in forty-seven allozyme loci and a low frequency of polymorphism in proteins”) as because of the test subject in question. That species was
Acinonyx jubatus,
the cheetah.

Every schoolchild in America knows that the cheetah is the world's fastest mammal. Anyone who has seen and studied these
creatures in the field is liable also to argue that they are the most beautiful of all carnivores, and the most successful of all wild cats. A dozen years ago I spent one lucky hour watching four cheetahs stalk game on the East African savanna, and I still haven't begun to forget their gorgeous, prepossessing grace. But the cheetah today, despite appearances, is not well. It is genetically depauperate.

Though there may still be as many as 20,000 cheetahs at large on the plains of Africa, the gene pool of
A. jubatus
appears to be much smaller than it should be for that number—too small, perhaps, to carry the species through any sudden adversities. Insufficient genetic options equals insufficient adaptability. So far, admittedly, only one of the two remaining large populations has been investigated: the South African cheetah, not the East African. In the course of O'Brien's study, blood tests were done on fifty-five animals, some of those from the Transvaal, some from Namibia, a few that had previously been exported to zoos in the United States. This scattered group of cats turned out to have all the genetic diversity of a palace full of incestuous Romanovs.

Cheetahs are currently an endangered species. Twenty thousand is not such a large total, and the real number may be much less, possibly as low as 1,500. No one really knows, because the elusive habits of these animals make them very hard to count. Though officially protected in some of the countries where they occur, they are still occasionally threatened by fur poachers and stock-raising peoples. They are threatened even more by habitat loss. But the worst threat they face may be the genetic one. They are just dangerously short on genetic variety.

And that's one threat that we humans can't rectify. All we can do is give them time. A depleted population of animals can sometimes recover quickly. A depleted gene pool cannot. Thousands of new generations must be born and grow and achieve successful reproduction themselves, before the slow process of mutation will have restored a previous level of gene variations. Populations fall
and rise again at geometric rates but, like some morbidly hurtful memory, genetic impoverishment lingers afterward.

•   •   •

Where did those missing cheetah genes go?

O'Brien and his coauthors are cautious about offering speculation, but their work, together with what is known of the history of this species in both the recent and the distant past, suggests a couple of sad possibilities.

The cheetah evolved independently of the other big cats and arrived at its modern form much earlier. Today it stands separate from all other living representatives of the cat family, a lonesome anomaly that in some ways shares more in common with dogs. Besides being faster, it is far more delicate, more slender, and less imposingly armed than any lion or leopard. Its teeth are shorter. Its jaws are rather weak. Other cats can voluntarily retract their claws into claw sheaths, thereby preserving the sharp points for piercing and slashing; the claws of the cheetah, in contrast, are not fully retractile and grow dull from being walked on. A cheetah's footprint, consequently, looks more like the print of a wolf than like the great soft ominous pug of a tiger. Though it may travel in small social groups (a mother with kits, a mixed trio of adults, even a pair of bachelor males), the cheetah seems most often to perform the act of killing solitarily. As slight of build as it is, as poorly equipped with lethal weapons, it would have little chance of winning a meal at all, if not for speed.

Speed it has, of course—unequaled speed—as well as a nicely matched set of anatomical adaptations that make that speed possible. The femur bone of the cheetah's leg is elongated, unusual among cats. The spine is long and flexible, and it bows dramatically with each stride, giving still greater reach to the legs. Those short, blunted claws are good for traction and quick turns. The nasal openings are especially large, as are the bronchi and the lungs, invaluable for an animal that needs huge volumes of oxygen for burning huge amounts of energy in very brief stretches of
time. The heart is also large. The tail is long and held straight out, for balance, while the cheetah screams along at seventy miles per hour. Even the arteries are exceptionally muscular.
A. jubatus
is born to run.

More specifically, born to chase. The cheetah shows a few curious behavioral patterns that become comprehensible only in light of its anatomical assets and limitations, and one among these is perhaps the most intriguing: According to reliable observation, a cheetah will almost never attack a potential prey animal that does not bolt and run.

Its favored prey species are modest-sized grazers like the impala and the Thomson's gazelle, generally taken at weights less than the cheetah's own. But let an impala stand its ground (either from stupid daring or because it's paralyzed by fear) and the cheetah will pass it right by, focusing instead on one of the other herd members that has taken flight. For two or three hundred yards the cheetah will pursue at top speed, until (on a successful chase) it has pulled up beside the chosen impala's rear flank. Then it will do what is, to my mind, a charmingly roguish thing: It will swing out a paw (in mid-stride now, remember, at seventy miles per hour) and
trip
the impala.

The impala goes head-over-teakettle. The cheetah slams on its own brakes, and pounces. The actual killing is then accomplished with a throat bite—which must be held as long as it takes for the impala to strangle, since the cheetah's jaw muscles and teeth are too meager for chomping through the spine or ripping out the jugular. But what about that other brazen impala, the one left standing back at the start? Why did the cheetah choose to ignore it? No one can be sure, but the most plausible answer is that, without a high-velocity chase, without a well-timed trip, the speedy-but-weak cheetah simply has no means of knocking an impala off its feet.