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Paleontology Original Article by: Carlton E. Brett, Department of Geological Sciences, University of Rochester, Rochester, New York. Stephen Jay Gould, Formerly, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts. Content • Applications of paleontology • Systematics and taxonomy • Evolutionary paleontology • Biostratigraphy • Taphonomy • Ichnology • Paleoecology and paleoenvironmental analyses • Biological aspects • Evolutionary process and life history • Life properties • Sketch of life history • Related Primary Literature • Additional Reading Key Concepts • Paleontologists study the past history of life by analyzing fossil remains. • The field of paleontology lies on the boundary between two disciplines—biology and geology. • Paleontological applications include systematics/taxono- my, evolutionary studies, biostratigraphy, taphonomy, ich- nology, paleoecology, and paleoenvironmental analyses. • The biological aspects of paleontology support the evolution of life throughout geologic time. • The most fundamental fact of paleontology is that organisms have changed throughout the history of Earth and that each geological period has its characteristic forms of life. Access to this article is being offered to Ward's World readers for free from McGraw Hill's AccessScience. An award-winning online gateway to scientific knowledge, AccessScience offers exclusive articles writing by prominent scientists, links to primary research material, videos and animations, plus faculty-designed curriculum maps for teachers. Fig. 1: Fossil ferns of Paleozoic age represented by thin films of carbon. (Credit: Stephen Reynolds) The study of life history as recorded by fossil remains. Pale- ontology investigates the life of the past through analyses of preserved fossils and their traces (Fig. 1). The term fossil, from the Latin "fossilis" (digging; dug up), originally referred to a variety of objects dug from the Earth, some of which were believed to be supernatural substances imbued with mystical powers. However, in a modern context, fossils can be defined as recognizable remains or traces of activity of prehistoric life. This broad definition takes in a diversity of ancient remains, but specifically excludes inorganic, mineralized structures, even those that spuriously resemble life forms (for example, dendritic patterns of manganese crystals: dendrites), sometimes termed pseudofossils (false fossils). The definition of fossils makes several qualifying statements. For example, fossils must be recognizably tied to once-living organ- isms, excluding amorphous organic matter such as coal and petroleum, although these are certainly derived from the prod- ucts of organisms and are sometimes referred to as "fossil fuels." The definition also encompasses two broad categories of fossils: (1) remains that are primarily skeletal hard parts (body fossils) and (2) traces of activity that are evidence of behavior of living organisms (trace fossils). The latter can be broadly construed to include tracks, trails, burrows, borings, bite and gnaw marks, fe- cal remains (coprolites), and gizzard stones (gastroliths) polished in the digestive activity of dinosaurs. In addition, certain organ- isms, especially bacteria, archaeans, algae, and vascular plants, produce distinctive and unique organic molecules, whose de- graded remnants can be extracted from sediments and isolated; these biomarkers form a type of chemical fossil. + ward ' s science

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