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Morphometric study of the platform elements of Amydrotaxis praejohnsoni n. sp. (Lower Devonian, conodonts, Nevada)

Published online by Cambridge University Press:  19 May 2016

Michael A. Murphy
Department of Earth Sciences, University of California, Riverside 92521
Kathleen B. Springer
Department of Earth Sciences, University of California, Riverside 92521


The platform element of the conodont Amydrotaxis praejohnsoni n. sp. shows statistically significant morphological changes from the base to the top of the delta Zone (Lower Devonian). The changes occur particularly in mean denticle number, height and character of the anterior denticles, and shape of the basal cavity. The earliest forms have fewer denticles ( = 7.1), an enlarged, high anterior denticle, and a broadly flared posterior basal cavity, whereas late forms have more denticles ( = 9.4), equal-sized anterior denticles, and a narrow posterior basal cavity. There is no stasis phase in the species history, but rather a mosaic pattern in which the observed changes in the character states are seemingly independent of each other and proceed at variable rates.

Research Article
Copyright © The Paleontological Society 

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Berry, W. B. N., and Murphy, M. A. 1975 [imprint 1974]. Silurian and Devonian graptolites of central Nevada. University of California Publications in Geological Sciences, 110:1109.Google Scholar
Eldredge, N., and Gould, S. J. 1972. Punctuated equilibria: an alternative to phyletic gradualism, p. 82115. In Schopf, T. M. J. (ed.), Models in Paleobiology. Freeman-Cooper, San Francisco, California.Google Scholar
Geary, D. H. 1987. Evolutionary tempo and mode in a sequence of the Upper Cretaceous bivalve Pleurocardia. Paleobiology, 13:140151.CrossRefGoogle Scholar
Klapper, G. 1969. Lower Devonian conodont sequence, Royal Creek, Yukon Territory, and Devon Island, Canada. Journal of Paleontology, 43:127.Google Scholar
Klapper, G., and Murphy, M. A. 1980. Conodont zonal species from the delta and pesavis Zones (Lower Devonian) in central Nevada. Neues Jahrbuch Geologie–Palaeontologie Monatsheft, 1980, H8:490504.Google Scholar
Lane, H. R., and Ormiston, A. R. 1979. Siluro–Devonian biostratigraphy of the Salmontrout River area, east–central Alaska. Geologica et Palaeontologica, 13:3996.Google Scholar
Mawson, R. 1986. Early Devonian (Lochkovian) conodont faunas from Windellama, New South Wales. Geologica et Palaeontologica, 20:3971.Google Scholar
Murphy, M. A., and Berry, W. B. N. 1983. Early Devonian conodont-graptolite collation and correlations with brachiopod and coral zones, central Nevada. American Association of Petroleum Geologists, Bulletin, 67:371379.Google Scholar
Murphy, M. A., and Cebecioglu, M. K. 1984. Icriodus steinachensis and I. claudiae lineages (Devonian conodonts). Journal of Paleontology, 58:13991411.Google Scholar
Murphy, M. A., and Cebecioglu, M. K. 1986. Statistical study of Ozarkodina excavata (Branson and Mehl) and O. tuma Murphy and Matti (Lower Devonian, delta Zone, conodonts, Nevada). Journal of Paleontology, 60:865869.CrossRefGoogle Scholar
Murphy, M. A., and Cebecioglu, M. K. 1987. Morphometric study of the Genus Ancyrodelloides (Lower Devonian, conodonts), central Nevada. Journal of Paleontology, 61:583594.CrossRefGoogle Scholar
Murphy, M. A., and Cebecioglu., M. K. and Matti, J. C. 1983 [imprint 1982]. Lower Devonian conodonts (hesperius–kindlei Zones), central Nevada. University of California Publications in Geological Sciences, 123:182.Google Scholar
Murphy, M. A., and Cebecioglu, M. K., Walliser, O. H. 1981. Biostratigraphy and evolution of the Ozarkodina remscheidensis–Eognathodus sulcatus lineage (Lower Devonian) in Germany and central Nevada. Journal of Paleontology, 55:747772.Google Scholar
Pickett, J. 1980. Conodont assemblages from the Cobar Supergroup (Early Devonian), New South Wales. Alcheringa, 4:6788.CrossRefGoogle Scholar
Shaw, A. B. 1969. Adam and Eve, paleontology and the non-objective arts. Journal of Paleontology, 43:10851098.Google Scholar
Simpson, G. G. 1961. Principles of Animal Taxonomy. Columbia University Press, New York, 247 p.Google Scholar
Zar, J. H. 1984. Biostatistical Analysis. Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 718 p.Google Scholar