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The jugum and salinity tolerance of Greenfieldia (Brachiopoda: Late Silurian)

  • A. J. Boucot (a1), Fernando Alvarez (a2) and Arthur Leibold (a3)


While preparing the part of the Treatise on Invertebrate Paleontology dealing with Greenfieldia, Alvarez had problems with the absence of information regarding its jugum. GRABAU (1910, in Grabau and Sherzer) described the smooth, subequally biconvex, small shell Greenfieldia whitfieldi, the type species of his Greenfieldia, from the Late Silurian Greenfield Dolomite of northern Ohio. Grabau (1910, p. 149) remarked that the brachidium was unknown, with only the presence of laterally directed spiralia (Grabau, Pl. XXX, fig. 9) being indicated but not discussed in the text. Grabau (1910) considered a questionable assignment of Greenfieldia to the meristelloid Hindella. Boucot et al. (1965, p. H662), Berry and Boucot (1970, p. 155) and Berdan (1972, p. 16) all illustrated the difficulty in discriminating between the Late Silurian Protathyris, whose jugum is known and athyroid in type, and Greenfieldia with its unknown jugum. Jones (1978, p. 10) further emphasized the difficulty in discriminating between Protathyris and Greenfieldia owing to ignorance of the latter's jugum. Modzalevskaya (1979, fig. 7) described a jugum from a form assigned to Greenfieldia. The complex form of the jugum she illustrated, featuring a number of recurving branches, is entirely unlike that of Greenfieldia although relatively similar to that of Protathyris.



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Berdan, J. M. 1972. Brachiopoda and Ostracoda of the Cobleskill Limestone (Upper Silurian) of central New York. U.S. Geological Survey Professional Paper 730, 47 p.
Berry, W. B. N., and Boucot, A. J. 1970. Correlation of the North American Silurian Rocks. Geological Society of America Special Paper 102, 289 p.
Boucot, A. J., Johnson, J. G., Pitrat, C. W., and Staton, R. D. 1965. Spiriferida, p. H632H728. In Moore, R. C. (ed.), Treatise on Invertebrate Paleontology, Part H, Volume 2. Geological Society of America and University of Kansas Press, Lawrence.
Grabau, A. W., and Sherzer, W. H. 1910. The Monroe Formation of southern Michigan and adjoining regions. Michigan Geological and Biological Survey, Publication 2, Geological series 1, 248 p.
Jones, B. 1978. Taxonomy and intraspecific variation of Protathyris praecursor Kozlowski, 1929 from the Upper Silurian of Somerset Island, Arctic Canada. Journal of Paleontology, 52:827.
Modzalevskaya, T. L. 1979. K Sistematike Paleozoiskikh Atiridid. Paleontologicheskii Zhurnal, 2:4863.
Witzke, B. J. 1981. Silurian stratigraphy of eastern Linn and western Jones counties, Iowa, p. 138. In Geological Society of Iowa guidebook 35, 38 p.
Witzke, B. J. 1983. Silurian benthic invertebrate associations of eastern Iowa and their paleoenvironmental significance. Transactions of the Wisconsin Academy of Sciences, Arts, and Letters, 71:2147.
Witzke, B. J. 1987. Models for circulation patterns in epicontinental seas applied to Paleozoic facies of North American Craton. Paleoceanography, 2:229248.

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The jugum and salinity tolerance of Greenfieldia (Brachiopoda: Late Silurian)

  • A. J. Boucot (a1), Fernando Alvarez (a2) and Arthur Leibold (a3)


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