Wonderful Life: The Burgess Shale and the Nature of History Read Free Page A

explosion.
    The story of the Burgess Shale is also fascinating in human terms. The fauna was discovered in 1909 by America’s greatest paleontologist and scientific administrator, Charles Doolittle Walcott, secretary (their name for boss) of the Smithsonian Institution. Walcott proceeded to misinterpret these fossils in a comprehensive and thoroughly consistent manner arising directly from his conventional view of life: In short, he shoehorned every last Burgess animal into a modern group, viewing the fauna collectively as a set of primitive or ancestral versions of later, improved forms. Walcott’s work was not consistently challenged for more than fifty years. In 1971, Professor Harry Whittington of Cambridge University published the first monograph in a comprehensive reexamination that began with Walcott’s assumptions and ended with a radical interpretation not only for the Burgess Shale, but (by implication) for the entire history of life, including our own evolution.
    This book has three major aims. It is, first and foremost, a chronicle of the intense intellectual drama behind the outward serenity of this reinterpretation. Second, and by unavoidable implication, it is a statement about the nature of history and the awesome improbability of human evolution. As a third theme, I grapple with the enigma of why such a fundamental program of research has been permitted to pass so invisibly before the public gaze. Why is Opabinia , key animal in a new view of life, not a household name in all domiciles that care about the riddles of existence?
    In short, Harry Whittington and his colleagues have shown that most Burgess organisms do not belong to familiar groups, and that the creatures from this single quarry in British Columbia probably exceed, in anatomical range, the entire spectrum of invertebrate life in today’s oceans. Some fifteen to twenty Burgess species cannot be allied with any known group, and should probably be classified as separate phyla. Magnify some of them beyond the few centimeters of their actual size, and you are on the set of a science-fiction film; one particularly arresting creature has been formally named Hallucigenia . For species that can be classified within known phyla, Burgess anatomy far exceeds the modern range. The Burgess Shale includes, for example, early representatives of all four major kinds of arthropods, the dominant animals on earth today—the trilobites (now extinct), the crustaceans (including lobsters, crabs, and shrimp), the chelicerates (including spiders and scorpions), and the uniramians (including insects). But the Burgess Shale also contains some twenty to thirty kinds of arthropods that cannot be placed in any modern group. Consider the magnitude of this difference: taxonomists have described almost a million species of arthropods, and all fit into four major groups; one quarry in British Columbia, representing the first explosion of multicellular life, reveals more than twenty additional arthropod designs! The history of life is a story of massive removal followed by differentiation within a few surviving stocks, not the conventional tale of steadily increasing excellence, complexity, and diversity.
    For an epitome of this new interpretation, compare Charles R. Knight’s restoration of the Burgess fauna (figure 1.1), based entirely on Walcott’s classification, with one that accompanied a 1985 article defending the reversed view (figure 1.2).
    1.The centerpiece of Knight’s reconstruction is an animal named Sidneyia , largest of the Burgess arthropods known to Walcott, and an ancestral chelicerate in his view. In the modern version, Sidneyia has been banished to the lower right, its place usurped by Anomalocaris , a two foot-terror of the Cambrian seas, and one of the Burgess “unclassifiables.”
    2.Knight restores each animal as a member of a well-known group that enjoyed substantial later success. Marrella is reconstructed as a trilobite, Waptia as a proto-shrimp