Bizarre Nassellariina (Radiolaria) from the Middle and Upper Jurassic of North America

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Abstract
Bizarre spumellarian-like nassellarians assignable to Perispyridium Dumitrica and TURANTA gen. nov. are common and often abundant in North American Middle and Upper Jurassic strata. Both genera, as far as can be determined with the data at hand, make their 1st appearance in the early Bajocian (Middle Jurassic) and their final appearance in the latest Kimmeridgian/early Tithonian (top of Zone 2 of Pessagno; emended herein). Ten new species of Perispyridium [P. alinchakense, P. dettermani, P. dumitricai, P. facetum, P. foremanae, P. gemmatum, P. nitidum, P. packardi, P. tamanense, P. tamarackense ] and 8 of Turanta [T. capsensis (type-species), T. barbara, T. flexa, T. lupheri, T. morinae, T. nodosa, T. officerensis, T. silviesensis ] are described from the Jurassic of Mexico, California, Oregon and Alaska [USA]. Many are short-ranging and should prove useful in developing a detailed zonation for Middle and Upper Jurassic radiolarian-bearing strata.