More than 30 Burgess Shale−type faunas are now known from the Lower and Middle Cambrian of Laurentia, South China, Australia, and Siberia (as well as a few other scattered locali− ties). These faunas are typified by arthropods, brachiopods, priapulans and sponges, and despite unique occurrences of particular taxa (such as halkieriids in Sirius Passet and fish in Chengjiang) they otherwise show quite a high degree of faunal homogeneity and temporal conservation. In the cynosure of such Lagerstätte, the celebrated Burgess Shale of British Co− lumbia, a notable component of the fauna are polychaete annelids. First described by Walcott (1911, 1931) they were rescrutinized by Conway Morris (1979), and his observations were very largely confirmed by Eibye−Jacobsen (2004). De− spite this considerable diversity and disparity of forms in the Burgess Shale it is noteworthy that the fossil record of Cam− brian polychaetes is otherwise exceptionally meager. Apart from the report herein from Sirius Passet, in our opinion the only other bona−fide example is a single specimen from the Spence Shale ofUtah (Robison 1969; see also Conway Morris 1979: 268, pl. 9: 130, 131). In this context it seems surprising, especially given its extraordinary richness, that no convincing polychaetes have been recognized in the Chengjiang Lager− stätte. A putative annelid has been illustrated by Chen et al. (1996: 142, figs. 175, 176; see also Chen and Zhou 1997: 37, fig. 34). These authors identify appendages as parapodia, but there seems to be no evidence for associated chaetae. An asso− ciated sclerite is also identified at the base of each supposed parapodium, and it is possible that this animal is better identi− fied as a lobopodian arthropod. In any event its polychaete af− finities seem very much open to question.
There is, it is true, a considerable roster of early fossil worms that have been assigned to the polychaetes but their status is almost universally problematic. Within the Edia− caran assemblage taxa such as Dickinsonia have been com− pared to spintherid polychaetes (Wade 1972). This is, how− ever, widely regarded as a case of convergence and whilst the status and phylogenetic affinities of the Ediacaran biotas are still controversial, there is no convincing identification of any sort of annelid. A significant component of the Cambrian fauna are the palaeoscolecidans (which as a group range to the Silurian), and these too have been assigned to the an− nelids (see Conway Morris 1977: 85–87; Conway Morris and Robison 1986). It is now clear, however, that palaeo−scolecidans are closely related to the priapulans, with the papillate bands representing rows of distinct sclerites that have no association with chaetae, let alone parapodia. Fi− nally, brief mention should be made of Myoscolex ateles from the Lower Cambrian of South Australia. In a detailed reappraisal by Dzik (2004) this worm was assigned to the annelids, with at least some similarity claimed to exist with the opheliids. This echoes the earlier remarks by Glaessner (1979), but is in conflict with a proposed affinity to the anomalocaridid arthropods (Briggs and Nedin 1997). Having examined some material with Romilly Everett (personal communication June 2005) we conclude that an assignment to the annelids is unlikely. In particular, the identification of phosphatic rod−like structures as chaetae (Dzik 2004) seems to be forced, but it must also be admitted that the comparison to the stem−group arthropods is not free of difficulties.