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A sample of the deep basinal Bone Spring Limestone (Leonardian) has yielded a diverse and superbly preserved assemblage of spumellarian radiolarians, associated with siliceous sponge spicules and conodonts. Radiolarians include typically Paleozoic paleoactinommids, entactiniids, and rotasphaerids; Permian albaillellids and parafollicucullids; and triradiate spongodiscids or hagiastrids. Triradiate forms, which include approximately 60% of the shells in the sample, have not previously been reported to be abundant in pre-Mesozoic rocks. Albaillellids and parafollicucullids are similar to forms reported from the Permian strata of Japan, but the Bone Spring forms do not fit in the biostratigraphic zonation proposed by Japanese workers. This may be due to gaps in the Japanese tratigraphic sections or to provincialism in radiolarian faunas.
Diversity in the Bone Spring assemblage is higher than in other Permian assemblages. Most reported Permian radiolarians have been recovered by HF extraction of cherts, while the Bone Spring specimens were extracted from limestone with acetic acid. Thus, diversity differences can be partly attributed to fortuitous preservation.
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