Fossils at a Glance
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Fossils provide a powerful tool for the study of the nearly 4-billion-year history of life, and its role in the evolution of Earth systems. They also provide important data for evolutionary studies, and contribute to our understanding of the extinction of organisms and the origins of modern biodiversity.
Fossils At A Glance is written for students taking an introductory level course in paleontology. Short chapters introduce the main topics in the modern study of fossils. The most important fossil groups are discussed, from microfossils through invertebrates to vertebrates and plants, followed by a brief narrative of life on Earth.
Diagrams are central to the book and allow the reader to see most of the important data “at a glance”. Each topic covers two pages and provides a self-contained suite of information or a starting point for future study.
This second edition has been thoroughly revised and brought up to date. It includes new line diagrams as well as photographs of selected fossils
cladistics. Codons – groups of three of the four molecules that make up DNA. They make up the letters of the genetic code. DNA (deoxyribonucleic acid) – double-stranded nucleic acid that contains genetic information. Genome – organism’s complete genetic material. Mass extinction – extinction of numerous species (greater than 10% of families or 40% of species) over a short time period. Molecular clocks – comparison of the rates of structural change in indicator molecules in different species.
Palaeontology and Evolution, Chapman and Hall, London (Figure 7.1e, f, p. 159). Figure 6.2a: redrawn and modified from Clarkson, E.N.K., 1998, Invertebrate Palaeontology and Evolution, Chapman and Hall, London (Figure 7.1a, b, p. 159); Figure 6.2b: redrawn and modified from Clarkson, E.N.K., 1998, Invertebrate Palaeontology and Evolution, Chapman and Hall, London (Figure 7.5a, p. 165). Figure 6.3: based on Ziegler, A.M., Cocks, L.R.M. and Bambach, R.K., 1968, Lethaia, 1, 1–27. Lingula: redrawn
12:07 Page 86 86 Chapter 10 Glossary Biserial – two-stiped graptolite, where the stipes are arranged back to back. Cephalic shield – highly adapted organ possessed by living pterobranchs with which they secrete their skeleton and fasten themselves to it. Collagen – fibrous protein characteristic of graptolites and pterobranchs. Cortical bandages – strengthening elements of the graptoloid rhabdosome added to the inside and outside of the skeleton by zooids, presumeably using their cephalic
until the process is halted by mineralization. Therefore the quicker the organism is mineralized the more complete the preservation, particularly of the soft tissues. Decay is limited in oxygen-poor environments. Decay rates are slower at lower temperatures and in acidic environments Transportation and fragmentation Burial Burial is an important factor in controlling the degree of preservation. Plants and animals that are buried rapidly in situ by a sudden influx of sediment tend to be better
Cypridina FAAC13 09/03/2009 12:12 Page 122 122 Chapter 13 Microvertebrates The conodont animal Conodonts Conodonts are small, phosphatic, tooth-like fossils that formed part of a complex feeding apparatus in an extinct eel-like fish. Ranging from the Cambrian to Triassic, they are important Palaeozoic biostratigraphic indicators. As their color changes with temperature of burial, they are used as indicators of thermal alteration in rocks. Morphology True conodont animals, preserved with