Tournayellinae, Calcareous Foraminifera in Mississippian Rocks of North America

By Betty Skipp, L. D. Holcomb, and R. C. Gutschick (Translations from original Russian of descriptions of several key genera and species by Ivan Mittin and Skipp). 38 pages, 7 figures, 7 plates. December 1966.

Abstract -- The Tournayellinae Dain, 1953, a subfamily of calcareous Foraminifera assigned to the Order Ammodiscida by Russian micropaleontologists, were first described from Devonian and Tournaisian (Lower Carboniferous) rocks of the U.S.S.R. Recent work in North America has shown them to be present in Kinderhook, Osage, and Meramec rocks, and to have restricted ranges useful for zoning. None have been recovered to date from the Devonian. A striking similarity between the tournayellid and endothyrid faunas of the Early Carboniferous of the North American Cordillera and several areas of the U.S.S.R. suggests coeval development, like environments, and possibly connecting seaways during that period. A correlation chart based on ranges of identical and similar Tournayellinae is presented in which the Osage/Meramec boundary of the United States (tentatively correlated with the Tournaisian/Visean boundary of western Europe) is interpreted to lie within and not above the Kizel Horizon of the U.S.S.R. Such an interpretation assigns many of the tournayellids to the Visean, rather than the Tournaisian.

Morphologically the Tournayellinae are unusual coiled forms in which the proloculus is followed by a tubular chamber apparently undivided in inner whorls, but subdivided in outer whorls by constrictions or septa. The tests are subovoid to discoidal and range in diameter from 0.2 to 2.0 mm. Present evidence suggests the test wall was originally composed of finely perforate porcellaneous(?) material which was later totally recrystallized. The tournayellids are most easily studied in thin section and are commonly associated with endothyrid Foraminifera. Manner of coiling and presence or absence of septa are the main generic distinctions.

Evolutionary trends determined by this study indicate that the apparently unchambered tube is a specialized feature of the test, which appears late in the evolution of the subfamily, actually just prior to its extinction in Chester time. This fact plus the similarity of endothyrid and tournayellid morphologic development and wall structure has led the authors to consider the subfamily, as represented in North America, a branch of the Family Endothyridae rather than a subdivision of the Order Arnmodiscida.

The genus Septaglomospiranella Lipina, 1955, for which one new subspecies is described, is found in the Redwall and Escabrosa Limestones, Arizona; the Leadville Limestone, Colorado; the Madison Limestone, Wyoming; the Tin Mountain Limestone, California; the Shunda and Pekisko Formations, Alberta, Canada; and the Gilmore City Limestone, Iowa. Septabrunsiina Lipina, 1955, for which two new species are described, is recognized in the Redwall, Leadville, and Madison Limestones, and in the Livingstone and Mount Head Formations, Alberta. Tournayella Dain, 1953, and Septatournayella Lipina, 1955, for which two new species are described, are found in the Redwall Limestone, the Madison Limestone, Montana, beds formerly assigned to the Brazer Limestone in southeastern Idaho and northern Utah, parts of the White Knob Limestone of Idaho, the Arroyo Penasco Formation, New Mexico, the Mount Head Formation, Alberta, and the Salem Limestone, Indiana.

A section containing translations into English of the original descriptions of major Russian genera and species discussed in this paper is appended.