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Cambrian strata of the Laurentian craton contain numerous examples of Burgess Shale–type faunas. Although displaying a more or less concentric distribution around the cratonal margin, most faunal occurrences are in present-day western North America, extending from the Northwest Territories to California. Nevertheless, the soft-bodied and lightly skeletalized fossils in most of these Lagerstätten are highly sporadic. Here, we extend knowledge of such Middle Cambrian occurrences in Utah with reports of four taxa. An arthropod from the Marjum Formation,Dytikosicula desmataegen. et sp. nov., is a putative megacheiran. It is most similar toDicranocaris guntherorum, best known from the younger Wheeler Formation, but differs primarily in the arrangement of pleurae and overall size. Along with a specimen of ?Yohoiasp, a new species ofYohoia,Y. utahanasp. nov., is described. It differs from the type and only known species,Y. tenuis, principally in its larger size and shorter exopods; it is the first description of this genus from outside the Burgess Shale. A new species of a stem-group lophotrochozoan from the Spence Shale,Wiwaxia herkasp. nov., possesses a palisade of dorso-lateral spines that are more robust and numerous than the type species ofWiwaxia,W. corrugata. Another notable taxon isEldonia ludwigifrom the Marjum Formation, which is interpreted as a primitive ambulacrarian (assigned to the cambroernids) and a new specimen of the ?cnidarianCambrorhytiumfrom the Wheeler Shale is illustrated.

The robust spines and sclerites of the early to middle Cambrian ‘mollusc’ Wiwaxia are ubiquitous in suitably preserved deposits, but are strikingly absent from the Chengjiang Lagerstätte (Cambrian Stage 3, Yunnan Province, SW China). Here we provide the first record of Wiwaxia sclerites from this rich deposit, extending the record of the genus to the earliest Cambrian Series 2. This reinforces the cosmopolitan distribution of this iconic Cambrian lophotrochozoan and demonstrates the strong faunal continuity that unites distant Cambrian Lagerstätten.

Wiwaxia is an extinct early metazoan with uncertain affinities, which is well represented in strata of Cambrian Series 2–3 age. Well-preserved representatives of Wiwaxia are known from the Burgess Shale Biota and the Kaili Biota. Here, new material of Wiwaxia corrugata (Matthew, 1899) is reported from the upper part of the Tsinghsutung Formation (Cambrian Series 2) near Balang Village, Guizhou Province, China. These specimens have a close evolutionary relationship to Wiwaxia taijiangensis Zhao, Qian & Lee, 1994 from the overlying Kaili Formation. New Wiwaxia material from the Tsinghsutung Formation and observations of specimens with articulated individuals from the Kaili Formation suggest that Wiwaxia taijiangensis should be a junior synonym of W. corrugata. A new study indicates that W. corrugata has a wide geographic distribution, a short geological history and evolutionary uniqueness and provides new data on taphonomy of this genus.

Microscopic teeth isolated from the early Cambrian Mahto Formation, Alberta, Canada, are identified as components of a molluscan radula, the oldest on record. Tooth-rows are polystichous and lack a medial rachidian tooth-column. Anterior-posterior differences in tooth-row morphology are interpreted as ontogenetic and correspond broadly to the diversity of isolated teeth, some of which correspond closely with those of extant aplacophoran molluscs. Associated pock-marked cuticular fragments are interpreted as having supported multiple biomineralized sclerites/spines in the manner of a modern chiton girdle. On the assumption that the cuticle and radula derive from the same species, there is a strong case for identifying this fossil as an aculiferan (aplacophoran + polyplacophora) mollusc, possibly a stem-group chiton. Similarities between the Mahto radula and the feeding apparatus of Wiwaxia and Odontogriphus are shown to be superficial. Terminal wear on some of the Mahto teeth indicate that they were used to scrape hard-substrates.

Halkieriids are part of a distinctive Early Cambrian fauna, the ''Tommotian fauna'' sensu Sepkoski (1992), that is preserved mostly as phosphatic and secondarily phosphatized skeletal elements. The distinctiveness of the Tommotian fauna is ascribed, in part, to its preferential elimination during the end-Early Cambrian mass extinction event (the ''Botomian extinction''). Newly discovered halkieriids in phosphatic limestones of the Middle Cambrian (Ptychagnostus gibbusZone) Monastery Creek Formation, Georgina Basin, Australia, now indicate that this group not only survived the end-Early Cambrian extinction, but was at least locally abundant thereafter. Most of the Georgina halkieriid sclerites can be accommodated within a single species, Australohalkieria superstes new genus and species, described and partly reconstructed here. Remaining sclerites probably represent two additional but rare halkieriid species. Additional newly discovered sclerites may have affinities with the sachitids, another problematic ''Tommotian'' taxon related to the halkieriids. Rare wiwaxiid sclerites extend the taphonomic and geographic distribution of this clade. The Monastery Creek Formation provides a valuable window on Middle Cambrian life, both because it provides information that is distinct from but complementary to other, similarly aged windows (e.g., the Burgess Shale) and because it represents a taphonomic window similar to those that preserve Early Cambrian small shelly problematica. A decline during the Cambrian in conditions necessary for the early diagenetic phosphati- zation of shallow-shelf and platform limestones may have effectively closed this taphonomic window, potentially biasing apparent patterns of diversity change through the period.

The early Cambrian Chengjiang Lagerstatte, Yunnan Province, Southwest China, has become one of the most celebrated Cambrian fossil Lagerstatten not only for perhaps the earliest biota of soft-bodied organisms in the Phanerozoic (Yuan and Zhao, 1999; Zhang et al., 2001; but see Budd and Jensen, 2000), but also for a number of significant discoveries (Shu et al., 1996a, 1996b, 1999a, 1999b, 2001), proven to be of particular importance for our understanding the Cambrian explosion. Also in Southwest China, Guizhou Province, there is a very significant, although less acclaimed, Middle Cambrian soft-bodied fauna as well, namely the Kaili fauna, which occurs in the Kaili Formation in Kaili area (Kuizhou). The age of the Kaili Formation ranges from late Early to early Middle Cambrian. Regionally, the Kaili Formation is about 222 m thick and consists of three parts. The lowermost part (late Early Cambrian, about 55 m thick) is dominated by thin, calcareous siltstone strata interbedded with limestone layers at the base. The middle part (early Middle Cambrian, ca. 123 m) consists of dark green mudstone and shale, while the uppermost part (ca. 44 m) is composed of interbedded limestone and silty shale. The Kaili fauna is derived from mudstones in the middle part of the formation (Zhao et al., 1994; Zhu et al., 2000). The Kaili fauna, similar to the Burgess Shale fauna, includes soft-bodied as well as skeletonized animals. The composition of this fauna is dominated by trilobites and characterized by abundant echinoderms (Zhao et al., 1994a, 1994b). Moreover, it contains some components of the Burgess Shale, e.g., Wiwaxia (Zhao et al., 1994c) and Canadaspis (Yuan and Huang, 1994). Recently, large scale collecting campaigns by a working group from the Guizhou University of Technology, moving from the original Wuliupo section to …

Charles D. Walcott's thin sections of the Middle Cambrian Burgess Shale of British Columbia, Canada, have yielded many specimens of the helically coiled microfossilObruchevella delicata, as well as fragments of the cyanobacteriaMarpoliaandMorania, sphaeromorph acritarchs, and sclerites of the enigmatic metazoanWiwaxia. Obruchevellaof the Burgess Shale displays a spectrum of preservation styles ranging from tangled masses to well-developed helixes. AllObruchevellaspecimens are preserved in three dimensions, which suggests original skeletalization or early post-mortem mineralization of the organism. Morphologic analysis ofObruchevellasupports an affinity with modern helical cyanobacteria. Study of all reported occurrences ofObruchevellaindicates that: 1) the genus has been overly split into seventeen species; 2) no correlation between size and age ofObruchevellaexists; and 3) mostObruchevellaspecimens are tightly coiled and have helix diameters four to six times their filament diameters.

The enigmatic fossil Wiwaxia corrugata is organically preserved in the Burgess Shale (Middle Cambrian, British Columbia) and is therefore extractable by careful acid maceration of the mineralic matrix. High magnification transmitted light microscopy and SEM of macerated Wiwaxia sclerites reveal a substantial amount of previously undescribed structural and microstructural detail. Anatomical and histological comparison with modern organisms indicates that Wiwaxia sclerites are polychaete paleae (flattened setae) and that Wiwaxia was a jawed annelid broadly related to the extant polychaete families Chrysopetalidae and/or Aprhoditidae (Palmyra). Canadia spinosa, an uncontested fossil polychaete from the same beds, shows a paleal microstructure identical to that of Wiwaxia, as well as a closely comparable gross anatomy and taphonomic grade. The unique combination of taxonomically significant characters shared by Wiwaxia and Canadia suggest that they are more closely related to each other than either is to any other fossil or extant polychaete. Thus they constitute a separate superfamily, Canadiacea superfam. nov., in the order Phyllodocida.