A NEW OCCURRENCE OF THE "HYDROZOAN" RADIOTRABECULOPORA RETICULATA FAN, RIGBY, AND ZHANG, 1991 IN THE PERMIAN OF CALIFORNIA

Journal of Paleontology, Mar 2004 by Rigby, J Keith, Linder, Gloria A, Stevens, Calvin H

Yancey (1976), in his summary of Permian biogeography, differentiated four major faunal provinces in western North America, including a Boreal province in the north, a CordiHeran province in cratonal western United States, and a Grandian province in Texas and Mexico. he grouped much of British Columbia and the western coastal states of the United States into an area characterized by "chaotic biotas." The Inyo Mountains of east-central California belong to what he designated as the Cordilleran province, as shown by the continuity of stratigraphy with lhe remainder of the Great Basin (e.g., Ross, 1965). In addition, Permian colonial coral faunas (Stevens, 1982) and many of the fusulinids are quite similar to those of east-central Nevada and West Texas, although some of the Inyo Mountains fusulinids apparently are endemic (Magginetti et al., 1988).

Later, Bambach (1990) recognized four major Early Permian biogeographic realms, including the Siberian, American, Tethyan, and Austral realms, based on broad, large-scale, paleontological studies of several invertebrate groups. Within the Early Permian of the American realm, he recognized an Alaska-Yukon, a South Laurentian, and a Cordilleran Province. (Bambach, 1990, fig. 8, table 5). The Inyo Mountains locality of the fossils described here falls within the northwestern part of his Cordilleran Province, in a general tropical position near the western margin of North America.

No fossils in the California Permian collection, other than the "hydrozoan" described here, show a close affinity to Tethyan forms. Thus, the presence of Radiotrabeculopora reticulata in southern China and the Cordilleran province, only, is difficult to explain. Neither dispersion through the Uralian seaway nor a possible seaway postulated as connecting the western Mediterranean with Texas (Stevens, 1985) during the Permian seems likely because of the lack of this "hydimoan" in the Urals and Texas, respectively.

This part of California was tropical during the late Wolfcampian, as indicated by the presence of an oldhaminoid brachiopod, probably Leptodus Kayser, 1882, and the epimastoporid algae in the same unit as the "hydrozoan." Possibly this latter fossil, the "hydrozoan," was able to disperse in some manner through the tropical waters of the enormously wide Paleopacific or Panthalassic Ocean. Wahlman (2002, (ig. 3), for example, shows an equatorial current along the California margin of North America that then crosses the broad Paleopacific Ocean toward southern China along its western margin.

ACKNOWLEDGMENTS

We are grateful for the support of staffs of the Geology Departments of San Jose State University and Brigham Young University. We also thank G. Wahlman, formerly of AMOCO Production Company, and now with BP America, Houston, Texas, for his evaluation of the algae. We appreciate the helpful and constructive reviews of the paper by C. Stock and B. SenowbariDaryan.

REFERENCES

BAMBACH, R. K. 1990. Late Palaeozoic provinciality in the marine realm, p. 307-323. In W. S. McKerrow and C. R. Scotese (eds.), Palaeozoic Palaeogeography and Biogeography. Geological Society (London) Memoir, 12.