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Storm-generated event beds are an important source of paleoecological information, especially in Paleozoic strata. Storm deposition and subsequent physical and biological modification can potentially alter the diversity structure of death assemblages significantly. To examine the effects of storm deposition on fossil assemblage composition, storm beds are compared with co-occurring beds representing background sedimentation in 67 samples from six Ordovician mixed carbonate-clastic units deposited above the maximum storm wave base. In the great majority of pairwise comparisons, evenness and sampled richness are higher in storm beds than in background beds. This effect is not explained by differences in lithification, skeletal fragmentation, or in the proportions of aragonitic or multielement skeletons. The elevated diversity of storm beds can result from homogenization of fine-scale faunal patchiness preserved in background beds or may be due to taphonomic feedback. The relative importance of these two end-member scenarios can be evaluated with detrended correspondence analysis. In shallow, carbonate-dominated environments, the former appears to predominate, while the latter is more important in a deeper setting dominated by fine-grained clastics. The disparity between background beds and storm beds suggests that, at least in the Lower Paleozoic, background beds may record a higher-resolution paleoecological signal while storm beds record a more complete census of alpha diversity. Because post–Middle Ordovician increases in the depth and intensity of bioturbation may have diminished the temporal resolution and increase the faunal completeness of background beds, this disparity is not necessarily expected in younger strata.

The Kanosh Formation of the Great Basin of western North America contains the oldest abundant and moderately diverse bryozoan fauna known from North America. Six species are here described from this formation at Ibex in the Confusion Range, Utah. They comprise three species of esthonioporine stenolaemates and three trepostomes. Two new genera (Ibexella and Kanoshopora) and three new species (I. multidiaphragmata, K. droserae, and Eridotrypa hindsi) are introduced. The endozone of Kanoshopora n. gen. is very unusual among bryozoans in being filled with vesicles that are divided by beaded walls into longitudinal files close to the boundary with the exozone.

Eriaster ibexensis n. gen. and sp., from the Ibexian (Lower Ordovician) of Utah, is the oldest-known body-fossil taxon of the class Asteroidea. Although important features are not preserved, the external form of E. ibexensis is suggestive of certain living asteroids and unlike approximately coeval somasteroids. The similar ages of Eriaster and the oldest-known somasteroid challenge the candidacy of the latter as basal to asteroids. Trace fossils assigned to Asteriacites have been recovered from strata as ancient as Lower Cambrian. Asteriacites from younger strata are considered to represent resting traces of asterozoans. Mode of formation of early representatives is problematic; however, their simple existence raises the possibility of extended pre-Ibexian asterozoan evolution, which could explain the morphological disparity found among the earliest-known body-fossil asterozoans.

Seven genera and eight species of lingulate brachiopods are described from the Cambrian-Ordovician boundary beds (Cambrooistodus minutus Conodont Subzone to Rossodus manitouensis Conodont Zone) at the Lawson Cove and Lava Dam North sections, Ibex area, Utah, USA. The fauna includes one new linguloid genus, Wahwahlingula, and four new species, Lingulella? incurvata, Zhanatella utahensis, Conotreta millardensis, and Quadrisonia? lavadamensis. Lingulate brachiopods from this interval are very poorly known from Laurentia, but the recorded fauna is very similar to that described from coeval beds at Malyi Karatau, Kazakhstan, and both areas contain Eurytreta cf. bisecta (Matthew, 1901); E. sublata Popov, 1988; Zhanatella Koneva, 1986; Schizambon Walcott, 1889; and Wahwahlingula. Eurytreta cf. bisecta is also known from the Lower Ordovician of Avalonian Canada, Britain, and Scandinavia.

Comparison of echinoderm faunas from two partly coeval Early Ordovician units, the Fillmore Formation of western Utah and the Ninemile Shale of central and southern Nevada, indicates that the distribution of echinoderms during the initial radiation of the Paleozoic Evolutionary Fauna was substrate-controlled. Attached echinoderms, such as crinoids and edrioasteroids, are much more common on hard substrates in the shallow-water Fillmore, whereas vagile forms, such as rhombiferans and mitrate stylophorans, are found on soft substrates in both the shallow-water Fillmore and deeper-water Ninemile. We found few intermediates or holdovers among these new Early Ordovician echinoderms, implying that the Cambrian and Paleozoic Evolutionary Faunas were most likely discrete and real and that the Ordovician Radiation was already well under way by the middle of the Early Ordovician. The commonly cited model of onshore-to-offshore expansion of newly evolved metazoan groups may be overly simplified for echinoderms because environmental factors such as substrate type appear to have controlled their distribution. Hard substrate availability represents an extrinsic ecologic cause for the initial diversification and later expansion of many attached echinoderms from onshore to offshore. Stemmed crinoids using discoidal hold-fasts first became abundant on hard substrates in shallow onshore environments, then expanded their range by developing rootlike holdfasts (or prehensile distal stems as adults) for living on soft substrates in both shallow and deeper water. This ability to exploit a wide range of substrates appears to have been a major factor in the over-whelming success of Paleozoic crinoids. Other diversifying echinoderm groups such as rhombiferans and mitrate stylophorans were already widespread on soft-substrates; they may have diversified much earlier on these substrates, or possibly they expanded from offshore, where they dominate the echinoderm fauna, to onshore.

Collections from upper Ibexian (Tulean Stage) rocks of western United States, from the Canning Basin in western Australia, and from the Argentine Precordillera contain a seximembrate apparatus of multidenticulate conodonts whose elements have been included by authors in species of Prioniodus Pander, 1986, and Reutterodus Serpagli, 1974. The individual elements as well as the complete apparatus are not consistent with assignment of the species to either of these genera or to any other extant genus. A new generic name, Stiptognathus Ethington, Lehnert, and Repetski, is proposed with Reutterodus borealis Repetski, 1982, as type species. The apparatus consists of Pa, Pb, Sa-c, and M elements; the genus represents either the Prioniodontidae or the Periodontidae.