F. T. Fuersich
Paleobiology as understood here refers to topics such as paleobiogeography, paleoecology, and evolution. As macroevolution is a separate theme of the meeting we discuss here only the first two aspects. Moreover we exclude also functional morphology, a major branch of paleoecology, because this too is a separate topic.
Taphonomy, i.e. the study of processes that operate on organisms from the moment of their death until weathering processes take over, has been established as a successful tool for palaeoenvironmental reconstructions. Originally the negative impact of taphonomic processes on the preservation of fossils formed the center of attention. Lately so-called "positive" taphonomy has moved to the forefront, stressing the diagnostic role of taphonomic features (left as taphonomic signatures on fossils) for depositional processes.
Paleoecology, in particular paleosynecology, enabled us to see assemblages of fossils as parts of former communities and ecosystems. While the buzz word "community evolution" has become unfashionable lately, after it was realized that communities do not evolve as entities, large-scale changes of communities do exist in geological history and reflect larger evolutionary patterns. Moreover the close relationship of communities with their environment makes fossil community relics excellent tools for identifying ancient environments. Speaking of concepts, paleosynecology has not made any significant progress within the last decade and appears to have reached a plateau relying heavily on ecological theories. Compared with the other two subjects, palaeobiogeography is still in its infancy. As its goal is to trace and to understand the distribution pattern of ancient organisms, paleobiogeography also contributes to the solution of paleogeographic problems, especially where other lines of evidence, e.g. paleomagnetic and tectonic data, are in conflict. This is particularly true of former positions of terranes. All three subjects play a double role in that they are firmly anchored in both biological and in geological problem solving. For example, taphonomy enables us to trace diagenetic, i.e. geochemical processes, but also evolutionary changes in the preservation potential of groups of fossil organisms (the recently proposed concept of taphonomic megabiases).
Palaeosynecology is a useful tool for facies and basin analysis, but also enables us to trace changes of ecosystems through time and the fate of evolutionary novelties within their ecological framework. Finally, palaeobiogeography is not just another useful palaeogeographic tool, but also aims at understanding dispersal patterns of organisms within their evolutionary and ecological context.
Needs for Future Development
Taphonomy. - Most taphonomic studies are case histories in which a particular data set is analyzed. The general significance of the results from such studies is often not clear. Taphonomy relies heavily on actualistic studies. We do not yet fully understand the significance of many taphonomic parameters. In order to develop reliable models for the interpretation of fossil material, we need more actualistic studies. Similarly, taphonomic studies require profound knowledge of sedimentological and geochemical processes. A stronger involvement of these neighboring disciplines and a stronger emphasis on experimental studies to calibrate taphonomic parameters are needed. Increasing attention is paid to the time factor, which in many cases determines the degree of taphonomic overprint of individual organisms or assemblages. Research should continue along these lines, especially with the respect to potential discrepancies between total time involved and length of time during which individual taphonomic processes operated.
Paleoecology. - In the past many paleosynecological studies failed to realize the limitation of their data sets. In particular taphonomic distortions were often disregarded with the result that such studies are of questionable value. A taphonomic analysis is therefore a prerequisite for any paleoecological analysis. More emphasis should be placed on the different time frames represented by fossil assemblages. We are still far from having comprehensive information about community relics for many environments and time slices of the geological past. Clearly, future research must be aimed at filling existing gaps. Still, with synecological data gradually becoming available for different environments and the different time slices of the geological record, larger scale trends in the temporal and spatial pattern should increasingly be studied to better grasp the mechanisms and controls of changes in ecosystems. This refers to time intervals with apparent "stasis" of ecosystems, as well as to time intervals, which record drastic changes (e.g. in connection with mass extinctions and their recovery phases). Such studies are beyond the expertise of individual paleontologists and thus require the combined effort of teams of taxonomists and paleoecologists. There is considerable predictive power in this approach, once general trends have been distilled from largely empirical and descriptive studies.
Paleobiogeography. - As a science, paleobiogeography is still in its infancy. At the moment, many different approaches are tried out, whereby the descriptive element ("story telling") still predominates. Clearly, in many cases the database for paleobiogeographic analyses is at present very fragmentary and needs to be greatly improved. However, we need also a stronger quantitative and statistical approach and the incorporation of ecological and environmental data. Ideally, we should end up with a uniform concept which enables us to compare results gained by different workers for different groups of organisms and for different periods of time. Then we could start relating changes in the global distribution pattern of organisms to the evolutionary and adaptational history of clades as well as to plate tectonic and major climatic and oceanographic changes. First steps have been taken in this direction, but the available database is still far from being satisfactory.
Major Problems To Overcome
Taphonomy. - One problem of taphonomy is that the objects of study are usually particular taxonomic groups. Thus we have researchers studying the taphonomy of bones, others that of shells, of leaves, or of microfossils. We need more interaction between these various specialists in order to understand the fundamental taphonomic problems common to all of them. Another serious hurdle is the difficulty to understand and evaluate the role of time for taphonomic processes. As has been shown, the degree of taphonomic degradation is no simple function of time represented by a particular fossil assemblage, but depends on the length of time and rates at which various taphonomic factors were operating.
Paleoecology. - Most paleosynecological studies suffer from dealing only with particular groups of fossils, that is they do not even fully utilize the available fossil record. A multifaceted approach involving specialists of the different taxonomic groups would increase the fidelity of synecological studies. A close cooperation with sedimentologists would lead to fine-tuning of the environmental parameters which, after all, usually exert a major role in shaping composition and structure of communities. A major hurdle is that fossil assemblages reflect the original communities from which they are derived to a varying degree depending on the proportion of preservable taxa in the total community. Maybe the biggest problem is the limit of temporal resolution. Due to time-averaging most fossil community relics cannot be compared with the preservable remains of present-day communities. As time-averaging also varies between fossil community relics, the evaluation of this feature is a must, should any fossil community analysis produce meaningful results. Similarly, selective dissolution, during diagenesis, of particular skeletal elements may be difficult to tell apart from a primary signal (e.g. does a community relict consisting only of calcitic epifaunal bivalves and brachiopods reflect particular ecological conditions or is it a result of preferential dissolution of aragonitic infaunal bivalves?). Another problem is overinterpretation of fossil data. This is always a temptation and can be counteracted by a clear idea of the limitations of the paleosynecological approach. Finally, a serious problem is also the fact that quantitative paleosynecological analyses are extremely time-consuming, as they usually involve a lengthy preparation and identification phase based on a detailed knowledge of the taxonomy of the taxa involved.
Paleobiogeography. - The biggest hurdle for paleobiogeographic analyses are reliable databases. A database must be large enough to be statistically meaningful. Because of this many paleobiogeographic studies are based on literature data. Composite literature data are, however, invariably inaccurate, relying on information of differing quality and detail (e.g. on facies or stratigraphic occurrence of a particular taxon) and reflecting different taxonomic concepts. This means that such analyses must be preceeded by a thorough taxonomic revision of the group under consideration. Another problem is that the different analytical methods employed at present make it very difficult to compare results from different studies. A uniform concept should improve this situation.
Taphonomy and paleoecology have the potential to become integral parts
of basin analysis, sequence stratigraphic studies, and larger-scale evolutionary
studies. Palaeobiogeography in turn should be an essential part of larger-scale
palaeogeographic reconstructions but helps us also to understand the reaction
of the biosphere to global changes. For all three subject areas a stronger
cooperation among paleontologists and with neighbouring disciplines would
be highly beneficial.
Paleoecology/Paleobiology (including Taphonomy) Delegates
Prof. Franz T. Fuersich--Topic Coordinator
Institut fuer Palaeontologie der Universitaet Wuerzburg
Pleicherwall 1, D-97070
Prof. David J. Bottjer
Dept. of Earth Sciences
University of Southern California
3651 University Avenue
Los Angeles, CA 90089-0740
Prof. Dr. Volker Mosbrugger
Institut fuer Geologie und Palaeontologie
Universitaet Tuebingen, Sigwartstr. 10
72076 Tuebingen, Germany
Prof. Dr. Werner Piller
Institut fuer Palaeontologie
Geozentrum de Universitaet Wien
A-1090 Vienna, AUSTRIA
0043 1 31336 784 (FAX)
0043 1 31336 9755 (PHONE)
Dr. John Flynn
Field Museum of Natural History
Department of Paleontology
Roosevelt at Lakeshore Drive
Chicago, IL 60605-2496 USA
312-922-941-ext. 374 or 291
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