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21 - Construction and Use of Geological, Geochemical, and Paleobiological Databases
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- By J. M. Hayes, Indiana University, Stefan Bengtson, Uppsala Universitet, Hans J. Hofmann, University of Montreal, Jere H. Lipps, University of California, Donald R. Lowe, Stanford University, Carol Mankiewicz, Beloit College, Carl V. Mendelson, Beloit College, Toby B. Moore, University of California, Bruce N. Runnegar, University of California, Harald Strauss, Ruhr-Universität Bochum
- Edited by J. William Schopf, University of California, Los Angeles, Cornelis Klein, University of New Mexico
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- Book:
- The Proterozoic Biosphere
- Published online:
- 04 April 2011
- Print publication:
- 26 June 1992, pp 855-864
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Summary
The earlier collaborative project of the PPRG (1979–1980; Schopf 1983a) used a great deal of paper. As analytical work neared completion, handwritten “scoreboards” and “hit lists” were compiled to be sure that work proceeded efficiently and that important samples were not missed. As tables of results were prepared, extensive bibliographies were developed relating to stratigraphic relationships and sedimentary ages. Participants in the project reworded the accumulating paper like so many burrowing animals. When, for example, a decision was reached about the age to be estimated for a particular rock unit, multiple tabular entries had to be changed. Much communication focused on keeping the records straight rather than on questions of interpretation.
The “personal-computer revolution” preceded the beginning of the current PPRG project. Many of the researchers involved had already developed computerized databases, and it was resolved that the power and flexibility of this technology would be applied to the sample-tracking and information-management problems of PPRG. Three problem areas were identified: (i) construction of unified bibliographic database that could be searched and which could be used for preparation of the reference list for the final publication; (ii) management of the sample inventory and laboratory work; and (iii) compilation of results and related information. Systems were eventually developed in all of these areas as described briefly below. In spite of efforts at coordination, the degree of integration initially hoped for was not achieved, principally because the databases were, in their organization a well as contents, the result of individual efforts.
5 - Proterozoic and Selected Early Cambrian Microfossils: Prokaryotes and Protists
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- By Carl V. Mendelson, Beloit College, John Bauld, Bureau of Mineral Resources, Robert J. Horodyski, Tulane University, Jere H. Lipps, University of California, Toby B. Moore, University of California, J. William Schopf, University of California
- Edited by J. William Schopf, University of California, Los Angeles, Cornelis Klein, University of New Mexico
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- Book:
- The Proterozoic Biosphere
- Published online:
- 04 April 2011
- Print publication:
- 26 June 1992, pp 175-244
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Summary
This Chapter considers the preserved, known record of Proterozoic and selected Early Cambrian microfossils: the microbiology of the middle eon of earth history. The evolutionary changes (evidenced morphologically) that took place during the Proterozoic were somewhat transitional between those of the preceding Archean (Section 1.5) and succeeding Phanerozoic Eons. The Early Proterozoic record is dominated by simple bacterial and cyanobacterial prokaryotes, some of which exhibit a significant degree of morphological complexity by about 2 Ga (Section 5.4); by the Late Proterozoic, various types of eukaryotic phytoplankters had arisen, including “giant” sphaeromorph and acanthomorph acritarchs as well as the enigmatic melanocyrillids. The evolutionary fabric of the Proterozoic is a complex one, and holds the key to the evolution of significant grades in microbiological organization. Here we attempt to dissect that fabric so that we can study it with critical and (we hope) open eyes.
Although the amount of information available for the task is less than one might prefer, it nevertheless is immense, even overwhelming; included in this mass of data are many uncritical reports of microfossils that must be filtered out before meaningful interpretations can be made. We might compare this dataset to that available for recent reviews of the Archean (Schopf and Walter 1983) and Early Proterozoic (Hofmann and Schopf 1983) microbiotas. The Archean compilation included 43 categories of microfossils and microfossil-like objects from 28 geologic units; two of these categories were accepted as representing true microfossils.
22 - Proterozoic and Selected Early Cambrian Microfossils and Microfossil-Like Objects
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- By Carl V. Mendelson, Beloit College, J. William Schopf, University of California
- Edited by J. William Schopf, University of California, Los Angeles, Cornelis Klein, University of New Mexico
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- Book:
- The Proterozoic Biosphere
- Published online:
- 04 April 2011
- Print publication:
- 26 June 1992, pp 865-952
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- Chapter
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Summary
The PPRG microfossil database (MICRO.DBF) contains information regarding approximately 3500 occurrences of Proterozoic and Early Cambrian microfossils and microfossil-like objects reported from about 470 stratigraphic units, the data included being based on analysis of 316 published papers, monographs, and books. This compilation forms the primary foundation for interpretations discussed in Sections 5.4, 5.5, 11.3, and Chapter 25. Tables 22.1–22.3, below, contain only a fraction of the information stored in the database; a brief description of the types of data stored (and of the database structure) is presented in Chapter 21.
Coverage
Table 22.3 includes an estimated 90 percent of all occurrences of authentic Proterozoic microfossils reported prior to August, 1988. Data from some relatively minor Soviet, Chinese, and Indian papers are not included, and a few significant Chinese monographs appeared too late to be covered. The Early Cambrian data are not comprehensive, but are perhaps representative; about 40% of the reported occurrences of Early Cambrian nonmineralized microfossils have been entered. The coverage in Tables 22.1 and 22.2 is a bit more eclectic. Because of time constraints, a number of papers containing descriptions of nonfossils, pseudofossils, and dubiofossils (see below for definitions) were not analyzed. The amassed data, although not complete, represent the largest compilation of this type now available for Proterozoic microfossils.
Content
Tables 22.1, 22.2, and 22.3 are based on the illustrated literature of Proterozoic and Early Cambrian microfossils and microfossil-like objects.
Acritarchs
- Carl V. Mendelson
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- Journal:
- Studies in Geology, Notes for a Short Course / Volume 18 / 1987
- Published online by Cambridge University Press:
- 19 July 2017, pp. 62-86
- Print publication:
- 1987
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In 1934 the Geological Society of America published its second Memoir: “Paleozoic Plankton of North America,” by Rudolf Ruedemann. This work was concerned primarily with invertebrates, especially the enigmatic and now-extinct graptolites. The primary producers of that era were virtually unknown; accordingly, the author devoted only a few pages to description and discussion of seaweeds. And although Ruedemann (1934, p. 25) recognized that “the microscopic algae must be considered as the very basis” of Paleozoic life, he submitted that “obviously it will be difficult to find their remains in the Paleozoic rocks.” O.M.B. Bulman (1964, p. 467), another graptolite expert, condensed his discussion on the primary producers to two paragraphs in “Lower Palaeozoic Plankton,” his Anniversary Address as President of the Geological Society of London; but at least he acknowledged the “universal occurrence” of fossil phytoplankters.