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The taphonomy of gastropod shell accumulations in large lakes: an example from Lake Tanganyika, Africa

Published online by Cambridge University Press:  08 April 2016

Andrew S. Cohen
Andrew S. Cohen*
Affiliation:
Department of Geosciences, University of Arizona, Tucson, Arizona 85721
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Abstract

An investigation of shell morphometrics of the prosobranch genus Paramelania from Lake Tanganyika shows striking contrasts between some live and dead populations from identical localities. Living populations and surficial dead shells were collected from 15 sublittoral-profundal localities along the east side of the lake. Interpopulation variability in this endemic gastropod is clinal (N-S) for several shell characters. Intrapopulation variability of dead shell populations frequently exceeds that of live populations. Distinctive morphs may be present in a local dead shell population which are absent in the live population from the same locality. However, the phenodeviant dead shell morphology may occur among live snails elsewhere in the lake. Phenodeviant shells may be encrusted, but are unabraded and show no preferred orientation.

Radiocarbon ages of >2000 yr b.p. on dead phenodeviants suggest that surficial shell accumulations in Lake Tanganyika are strongly time-averaged. Although wave activity and biogenic concentration are important processes in Lake Tanganyika, neither is sufficient under modern lake conditions to account for these admixed assemblages. Winnowing and in situ stratigraphic condensation during periods of lowered lake levels is the most likely explanation for the occurrence of phenodeviant surficial shells. This hypothesis is consistent with the observation that extensive shell lags are exposed on the lake floor in areas currently inhabited by the same snails.

A model of biogeographic range fluctuations for particular Paramelania morphs during the Holocene, in concert with lake level fluctuations, can account for the shell assemblages seen on the lake floor today. The complex history of these accumulations suggests that taphonomic admixtures may obscure the interpretation of evolutionary sequences in the lacustrine stratigraphic record.

Type
Research Article
Information
Paleobiology , Volume 15 , Issue 1 , Winter 1989 , pp. 26 - 45
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Abrahao, D. 1987. Lacustrine and Associated Deposits in a Rifted Continental Margin: The Lagoa Feia Formation, Lower Cretaceous, Campos Basin, Brazil. Unpublished M.S. thesis, Colorado School of Mines. Golden, Colorado.Google Scholar
Bader, R. 1955. Variability and evolutionary rate in the ore-odonts. Evolution 9:119–140.Google Scholar
Bell, M., Sadagursky, M., and Baumgartner, J. 1987. Utility of lacustrine deposits for the study of variation within fossil samples. Palaios 2:455–466.Google Scholar
Bertani, R., and Carozzi, A. 1984. Microfacies, depositional models and diagenesis of Lagoa Feia Formation (Lower Cretaceous) Campos Basin, offshore Brazil. Rio De Janeiro Centro De Pesquisas Desenvolvimento, Petrobras Ciencia Tecnica Pe-troleo 14.Google Scholar
Brett, C. E., and Baird, G. 1986. Comparative taphonomy: a key to paleoenvironmental interpretation based on fossil preservation. Palaios 1:207–227.Google Scholar
Brown, D. 1980. Freshwater Snails of Africa and Their Medical Importance. Taylor and Francis Publishing Company; London.Google Scholar
Brown, D., and Mandahl-Barth, G. 1987. Living molluscs of Lake Tanganyika: a revised and annotated list. Journal of Conchology 32:305–327.Google Scholar
Capart, A. 1952. Le Milieu Géographique et Géophysique. Exploration Hydrobiologique du Lac Tanganika. Institut Royal des Sciences Naturelles de Belgique 1:1–27.Google Scholar
Cohen, A. 1987a. Skeletal accumulations and the taphonomy of lacustrine coquinites: evidence from modern lakes. Geological Society of America, Abstracts with Programs 19:267.Google Scholar
Cohen, A. 1987b. Fossil ostracodes from Lake Mobutu (L. Albert): paleoecologic and taphonomic implications. Paleoecology of Africa 18:271–281.Google Scholar
Cohen, A.In press. Facies relationships and sedimentation in large rift lakes: examples from Lakes Turkana and Tanganyika. Palaeogeography, Palaeoclimatology, Palaeoecology.Google Scholar
Cohen, A., and Johnston, M. 1987. Speciation in brooding and poorly dispersing lacustrine organisms. Palaios 2:426–435.Google Scholar
Cohen, A., and Schwartz, H. 1983. Speciation in molluscs from Turkana Basin. Nature 304:659–660.CrossRefGoogle Scholar
Cohen, A., and Thouin, C. 1987. Nearshore carbonate deposits in Lake Tanganyika. Geology 15:414–418.2.0.CO;2>CrossRefGoogle Scholar
Craig, H., Dixon, F., Craig, V., Edmond, J., and Coulter, G. 1974. Lake Tanganyika geochemical and hydrographic survey, 1973 expedition, report 75. University of California Scripps Institute of Oceanography; La Jolla, California.Google Scholar
Cunnington, W. 1920. The fauna of the African lakes: a study in comparative limnology with special reference to Tanganyika. Proceedings of the Zoological Society of London 1920:507–622.Google Scholar
Ebinger, C. 1988. Thermal and Mechanical Development of the East African Rift System. Ph.D. dissertation, Massachusetts Institute of Technology. Cambridge, Massachusetts.Google Scholar
Evert, M. 1980. Le Lac Tanganyika, sa Faune, et la Peche au Burundi. Université du Burundi Presse; Bujumbura, Burundi.Google Scholar
Gautier, A. 1970. The freshwater mollusks from the Chiwondo Beds (Malawi): a preliminary report. Quaternaria 13:325–330.Google Scholar
Haberyan, K., and Hecky, R. 1987. The Late Pleistocene and Holocene stratigraphy and paleolimnology of the Lakes Kivu and Tanganyika. Palaeogeography, Palaeoclimatology, Palaeoecology 61:169–197.Google Scholar
Hanley, J. 1976. Paleosynecology of nonmarine molluscs from the Green River and Wasatch Fms., SW Wyoming and NW Colorado. Pp. 235–261. In Scott, R., and West, R. (eds.), Structure and Classification of Paleocommunities. Dowden, Hutchinson and Ross; Stroudsburg, Pennsylvania.Google Scholar
Hecky, R., and Degens, E. 1973. Late Pleistocene-Holocene chemical stratigraphy and paleolimnology of the Rift Valley lakes of central Africa. Woods Hole Oceanographic Institute Technical Report 73–28.Google Scholar
James, W. C. 1980. Limestone channel storm complex (lower K) Elkhorn Mountains, Montana. Journal of Sedimentary Petrology 50:447–456.Google Scholar
Johnston, M., and Cohen, A. 1987. Modes of speciation in gastropods from Lake Tanganyika: morphometric evidence. Palaios 2:413–425.CrossRefGoogle Scholar
Kat, P., and Davis, G. 1983. Speciation in molluscs from Turkana Basin. Nature 304:660–661.Google Scholar
Kelts, K. 1988. Environments of deposition of lacustrine petroleum source rocks: an introduction. Pp. 3–26. In Fleet, A. J., Kelts, K., and Talbot, M. (eds.), Lacustrine Petroleum Source Rocks. Geological Society of London Special Publication 40.Google Scholar
Kidwell, S. 1985. Paleobiological and sedimentological implications of fossil concentrations. Nature 318:457–460.Google Scholar
Kidwell, S., Fursich, F., and Aigner, T. 1986. Conceptual framework for the analysis and classification of fossil concentrations. Palaios 1:228–238.Google Scholar
Leloup, E. 1953. Gastéropodes. Exploration Hydrobiologique du Lac Tanganika. Institut Royal des Sciences Naturelles de Belgique 3:1–273.Google Scholar
Meldahl, K. 1987. Sedimentologic and taphonomic implications of biogenic stratification. Palaios 2:350–358.Google Scholar
Mondeguer, A., Tiercelin, J. J., Hoffert, M., Larque, P., Le Fournier, P. J., and Tucholka, P. 1986. Sedimentation actuelle et recente dans un petit bassin en contexte extensif et décrochant: La Baie Be Burton, Fosse Nord-Tanganyika, Rift Est-Africain. Bulletin Centre de Recherche, Exploration et Production-ELF Aquitaine 10:229–247.Google Scholar
Moore, J. 1898. Descriptions of the genera Bathanalia and Bythoceras, from Lake Tanganyika. Proceedings of the Malacological Society of London 3:92–93.Google Scholar
Moore, J. 1903. The Tanganyika Problem. Hurst and Blackett; London.Google Scholar
Morrison, J. 1954. The relationship of old and new world melanians. Proceedings of the U.S. National Museum 103:357–394.Google Scholar
Norris, R. 1986. Taphonomic gradients in shell fossil assemblages: Pliocene Purisima Formation, California. Palaios 1:256–270.Google Scholar
Owen, R. B., Barthelme, J. W., Renault, R. W., and Vincens, A. 1982. Paleolimnology and archaeology of Holocene deposits NE of Lake Turkana, Kenya. Nature 298:523–529.Google Scholar
Pilsbry, H., and Bequaert, J. 1927. The aquatic mollusks of the Belgian Congo, with a geographical and ecological account of Congo malacology. Bulletin of the American Museum of Natural History 53:69–602.Google Scholar
Rhoads, D. C., and Stanley, D. J. 1965. Biogenic graded bedding. Journal of Sedimentary Petrology 35:956–963.Google Scholar
Rosendahl, B., Reynolds, D., Lorber, P., Burgess, C., McGill, J., Scott, D., Lambiase, J., and Derksen, S. 1986. Structural expressions of rifting: lessons from Lake Tanganyika, Africa. Pp. 29–43. In Frostick, L. et al. (eds.), Sedimentation in the African Rifts. Geological Society of London Special Publication 25.Google Scholar
Scholz, C., and Rosendahl, B. 1987. Late Pleistocene low lake levels in two African rift lakes. Geological Society of America, Abstracts with Programs 19:834.Google Scholar
Smith, E. 1881. Descriptions of two new species of shells from Lake Tanganyika. Proceedings of the Zoological Society of London 1881:559–561.Google Scholar
Smith, E. 1904. Presidential Address. Some remarks on the mollusca of Lake Tanganyika. Proceedings of the Malacological Society 6:77–104.Google Scholar
Sylvester-Bradley, P. C. 1977. Biostratigraphical tests of evolutionary theory. Pp. 41–63. In Kauffman, E., and Hazel, J. (eds.), Concepts and Methods of Biostratigraphy. Dowden, Hutchinson and Ross; Stroudsburg, Pennsylvania.Google Scholar
Van Straaten, L. 1952. Biogenic textures and the formation of shell beds in the Dutch Wadden Sea. Proceedings Koninklijke Nederlandse Akademie van Wetenschappen. Series B. Physical Sciences 55:500–516.Google Scholar
West, K., and Cohen, A. 1987. Experimental studies of decapod gastropod interactions at Lake Tanganyika: implications for predator prey coevolution. Geological Society of America, Abstracts with Programs 19:887.Google Scholar
Williamson, P. 1981. Paleontological documentation of speciation in Cenozoic molluscs from the Turkana Basin. Nature 293:437–443.Google Scholar
Williamson, P. 1983. Speciation in molluscs from Turkana Basin. Nature 304:661–663.CrossRefGoogle Scholar
Williamson, P. 1986. Selection or constraint? A proposal on the mechanism for stasis. Pp. 129–142. In Campbell, K., and Day, M. (eds.), Rates of Evolution. Allen and Unwin; Boston.Google Scholar