Exceptional Fossil Preservation: A Unique View on the Evolution of Marine Life

Exceptional Fossil Preservation: A Unique View on the Evolution of Marine Life

Exceptional Fossil Preservation: A Unique View on the Evolution of Marine Life

Exceptional Fossil Preservation: A Unique View on the Evolution of Marine Life

Synopsis

Most nonscientists are usually aware of fossils, and it is commonly believed that they are extremely rare. In fact, fossils are exceptionally common in many sedimentary rocks and are used extensively in geology for age dating, interpretation of ancient environments, and the discovery of natural resources. However, there is another type of fossil deposit that is truly rare. These rare fossil deposits, called Lagerst¿tten, preserve the remains of the soft tissues or the articulated skeletal remains of ancient creatures in truly astonishing fine detail. Some of these deposits are world-famous, such as the Burgess Shale, or Solnhofen but there are others dating from many different geological eras from the Paleozoic, up to the Eocene. Recently, a concerted effort has been made to understand the overall significance of these rare fossil deposits. Whereas in the past these deposits were considered novelties, modern researchers are trying to understand what they can tell us about ancient life and environments. New sophisticated techniques (including image and geochemical analyses) are providing enormous new contributions to our knowledge of Lagerst¿tten sites and to paleobiology in general. This volume describes many of the most famous Lagerst¿tten locations worldwide and is complete with over 70 superb halftones showing some of these exotic fossils in all their glory. Paleontologists are beginning to understand why such deposits occur, how they have varied since the advent of marine metazoan life, and how their presence effects our understanding of the evolution of life in the Earth's oceans. In this way, the study of Lagerst¿tten continues to move towards the mainstream of paleobiological, biological, and geological research, and away from its former status as the examination of mere curiosities. All those interested in these beautiful and sometimes enigmatic deposits will want to own this book.

Excerpt

Fossils, remains of ancient life, have played a large role in our exploration of the Earth's past. in antiquity they led to the recognition of sea-level oscillations. During the Renaissance, they raised questions about the tales of Genesis. in the nineteenth century, when paleontology became a science of its own, they served to develop an Earth history and demonstrated the great complexity of the tree of life. in the twentieth century, these concepts were greatly refined.

Part of what makes fossils so useful is their enormous abundance. in many outcrops, shells of clams or snails or brachiopods weather out by the hundreds, even thousands, and many limestone cliffs are replete with corals and bryozoans. a teaspoon of clay or chalk may contain hundreds of foraminifera or millions of coccoliths.

But such simply armored organisms constitute only a fraction of any living fauna. Carcasses with compound skeletons, such as echinoderms and vertebrates, are normally disarticulated, as they are torn apart by scavengers or rotted by bacteria and fungi, and few are the bones or ossicles that are not dragged off by scavengers; distributed by rivers, currents, and waves; or scattered by sediment burrowers. Animals with fairly standardized body plans, such as vertebrates, can still generally be assembled from scattered bones, but in the case of echinoderms, commonly having thousands to tens of thousands of individual ossicles and a baffling variety of body plans, the task is hopeless.

Beyond this, faunas include many animals that have little or nothing in the way of mineralized skeletons that escape bacterial decomposition. How and when did these groups evolve, and what role, if any, did they play in fossil faunas of the past?

Furthermore, extinct groups of animals often pose problems of relationship. Trilobites, for example, clearly were arthropods, but were they crustaceans, merostomes, or an independent and now wholly extinct . . .

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