Acritarchs from the MacLean Brook Formation, southeastern Cape Breton Island, Nova Scotia, Canada: New data on Middle Cambrian–Lower Furongian acritarch zonation Teodoro Palacios a, ⁎, Sören Jensen a , Sandra M. Barr b , Chris E. White c a Área de Paleontologia, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain b Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6 c Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia, Canada B3J 2T9 abstract article info Article history: Received 18 January 2008 Received in revised form 6 October 2008 Accepted 2 December 2008 Keywords: Cambrian Acritarchs Biostratigraphy Nova Scotia We present here the results of a pilot study on Cambrian acritarchs from Cape Breton Island, Nova Scotia, based on a material from the MacLean Brook Formation in the Mira River Valley. An assemblage from the base of the formation contains 8 species including Eliasum llaniscum, Cristallinium dubium and Symplasso- sphaeridium cambriense, and correlates with a position close to the Paradoxides davidis–P. forchhammeri Zone boundary. An assemblage from the upper part of the formation contains 16 species, of which 3 are new, including Cristallinium aciculatum, Petaloferidium lacrimiferum n. sp., Pirea orbicularis, Stelliferidium pingiculum, S. magnum n. sp., S. albanii n.sp, and Timofeevia microretis, correlated to the Olenus Zone. The upper assemblage is particularly noteworthy as it provides the first direct evidence for the Olenus Zone in the MacLean Brook Formation. Furthermore, it contains stratigraphically significant taxa known from sections on Baltica, and northern Gondwana but which have not been reported previously on Avalonia. The distinction between Stelliferidium and Timofeevia is discussed in part based on new data on Timofeevia lancarae from its type area in northern Spain. It is suggested that many reports of Furongian Timofeevia phosphoritica and T. lancarae are better referred to Stelliferidium. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Biostratigraphical zonation of the Middle Cambrian and Furongian (Upper Cambrian) is based mainly on trilobites with a particular detailed zonation of the Furongian established on the pelagic agnostids, and also on olenids. The base of the terminal Cambrian series was defined recently on agnostids, at the base of the Glyptag- nostus reticulatus Zone in sections in South China, which puts the boundary higher than that traditionally used in many regions (Peng et al., 2004). In facies where these types of trilobites are not commonly found, zones are based on polymeroid trilobites. For example, on Baltica and Avalonia the major divisions of the Middle Cambrian are based on a succession of paradoxidid trilobites, with subdivisions largely provided, where possible, by olenids and agnostids. Acritarchs, a polyphyletic assemblage of form taxa of planktic organic-walled cysts, provide further means of Middle Cambrian and Furongian biochronology, and have proven to be a useful compliment to trilobites in correlation across Avalonia, Armorica, Baltica and northern Gondwana. Because acritarchs generally can be extracted in great numbers from any fine-grained siliciclastic rock that was deposited under normal marine conditions, they provide means for detailed sampling, and locally may provide the only fossil age constraints. For example, from southern Spain, Palacios et al. (2006) recognized four Lower Cambrian–Middle Cambrian acritarch zones in a 500 m-thick succession barren of macrofossils. Middle Cambrian–Furongian acri- tarch-based zonations have been discussed by, among others, Martin and Dean (1981, 1988), Volkova (1990), Volkova and Kiryanov (1995), Vanguestaine (1978), and Vanguestaine and van Looy (1983), and summarized by Molyneux et al. (1996). Possibly the most widely used of these zonations — and of special interest to this paper because of its geographical proximity — is that of Martin and Dean (1981, 1988), which was established on sections in southeastern Newfoundland that also yield a moderately rich record of trilobites, thus providing means for calibrating the two types of zonation. On the East European Platform, a broadly comparable zonation has been developed by Volkova (e.g., 1990, 1996; Volkova and Kiryanov, 1995). The general applicability of Middle Cambrian–Furongian acritarch-based correlation is now firmly estab- lished. It is, however, also the case that current knowledge is based on a relatively small number of sections that provide independent age constraints, that the stratigraphical ranges of many taxa are incomple- tely known and that taxonomic issues remain unresolved. Here we report on Middle Cambrian and Furongian acritarchs from the MacLean Brook Formation, southeastern Cape Breton Island, Nova Scotia; this work is the first detailed documentation of Cambrian acritarchs in this region. Independent age control is provided by trilobites. The assemblages of acritarchs include several taxa known Palaeogeography, Palaeoclimatology, Palaeoecology 273 (2009) 123–141 ⁎ Corresponding author. E-mail address: medrano@unex.es (T. Palacios). 0031-0182/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2008.12.006 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo