The brachiopod Antiquatonia coloradoensis (Girty) from the upper Morrowan and Atokan (lower Middle Pennsylvanian) of the United States

Abstract

Primary type specimens and topotypes of the large, semireticulate productid, Productus inflatus var. coloradoensis (Girty), collected near Leadville, Colo., form the basis for the redescription of this species. The type locality, for the first time, is firmly established stratigraphically in upper Morrowan (lower Middle Pennsylvanian) rocks of the lower part of the Belden Shale. The identification and clarification of several previously poorly known physical features affirm assignment of Girty's species to the genus Antiquatonia Miloradovich, as currently restricted and understood. Detailed analysis of other collections of brachiopods assigned to A. coloradoensis and to related taxa confirms that the probable ancestor of A. coloradoensis is the lower and middle Morrowan A. morrowensis (Mather), which was described from the Ozarks region of northwestern Arkansas. One descendant of A. coloradoensis is A. hermosana (Girty), which is common in lower Desmoinesian strata of the southern Rocky Mountains and Paradox Basin. A descendant of A. hermosana may be A. portlockiana (Norwood and Pratten), which is common in uppermost middle and upper Desmoinesian strata in the Rocky Mountains and which is reported from Desmoinesian strata in the Midcontinent, Illinois Basin, and Appalachian Basin. However, the variability, taxonomy, and stratigraphic ranges of the species of Antiquatonia in the Desmoinesian of the eastern United States have not been resolved satisfactorily. The stratigraphic range of Antiquatonia coloradoensis extends from the upper part of the Morrowan Series through the Atokan Series. The known geographic range of this species extends from the Eastern Great Basin, through the southern Rocky Mountains, the southern and central Midcontinent area, to the eastern and southern Appalachian Basin. It is a moderately common to rare component of open-bay, shelf-lagoon, and shelf-margin marine facies.

New rhynchonellid and spire-bearing brachiopods from the Carboniferous of Mexico. Paleogeographical significance of the Oaxacan brachiopod fauna through the Serpukhovian–Moscovian

“…Remarks.-This species has been widely reported in the Pennsylvanian of the United States, with records in Nebraska, Kansas (Dunbar and Condra, 1932), New Mexico (Gehrig, 1958), Missouri (Hoare, 1961), Montana (Easton, 1962), Nevada (Lane, 1963), Ohio (Sturgeon and Hoare, 1968), Wyoming (Gordon, 1975), and Colorado (Henry, 1998). In addition to this material, >50 specimens represent both valves in the collection.…”