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Memoir 26—Fusilinids Millerella and Eostaffella from the Pennsylvanian of New Mexico and Texas

By W. E. King, 1973, 34 pp., 6 figs, 4 plates, 1 index.

Fusulinids of the genera Millerella and Eostaffella occur in great abundance in the Arrey and Apodaca Formations of the type lower Derry Series of New Mexico and the type Marble Falls Formation of Texas. The lower part of the Marble Falls Formation is assigned to the Morrowan Series, and the upper part of the Marble Falls to the Atokan Series. Comparison of the two sections on the basis of the Millerella-Eostaffella fauna indicates that these primitive genera do have stratigraphic utility and that the Atokan species of the upper part of the Marble Falls Formation compare favorably with the species of the lower part of the Derry Series. The Eostaffella assemblage of the Morrowan part of the Marble Falls Formation is distinct from the Atokan assemblage of both localities. Most of the species discussed are found in the Carboniferous of Russia and Japan and were first described in the Russian literature. This group of fusulinids has value for the correlation of the Lower Pennsylvanian of the US with the Carboniferous of Russia and Japan. One new species, Millerella extensus King, is described.     The purpose of this report is to present the stratigraphic occurrence of the primitive fusulinid genera Millerella and Eostaffella in the type Derry Series of NM and in the type Marble Falls Formation of Texas to determine their value as zonation fossils to the Morrowan and Early Atokan. Because American paleontologists have devoted little attention to these genera, little is known of their range and potential as index fossils. Most stratigraphic paleontologists working in the Pennsylvanian consider the Morrowan Series to be that part of the Pennsylvanian stratigraphic section devoid of fusulinids more advanced than Millerella and Eostaffella, and regard the base of the Atoka Series closely coincident with the first appearance of Profusulinella.

The author hopes that detailed examination of the Millerella-Eostaffella fauna in many localities will yield information for identifying important and useful biozones of the Morrow and lower Atokan strata. Russian and Japanese paleontologists are working extensively with the zoning objective in mind. This report, a beginning attempt to understand the significance of the genera, with information from two classic Lower Pennsylvanian sections, sheds some light on the abundance, variation, and range of certain species of the genera.

The author believes the Derry Series of New Mexico is roughly equivalent to the Atoka Series of North America, as defined on the basis of fusulinids. Whether the lowest part of the Derry Series, which has only fusulinids more primitive than Profusulinella, is Morrowan in age is not known. However, on the basis of a comparison with the Millerella-Eostaffella fauna of the Marble Falls Formation and the lowest Derry Series, the questionable part of the lowest Derry Series would seem to be Atokan.

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