Palaeobiogeographical data on Cambrian trilobites obtained during the twentieth century are combined in this paper to evaluate palaeoceanographic links throughc.30 myr, once these arthropods biomineralized. Worldwide major tectonostratigraphic units are characterized at series intervals of Cambrian time and datasets of trilobite genera (629 for Cambrian Series 2, 965 for Cambrian Series 3, and 866 for the Furongian Series) are analysed using parsimony analysis of endemicity. Special attention is given to the biogeographical observations made in microcontinents and exotic terranes. The same is done for platform-basinal transects of well-known continental margins. The parsimony analysis of endemicity analysis resulted in distinct palaeogeographical area groupings among the tectonostratigraphic units. With these groupings, several palaeobiogeographical units are distinguished, which do not necessarily fit the previously proposed biogeographical realms and provinces. Their development and spatial distributions are broadly controlled by Cambrian palaeoclimates, palaeogeographical conditions (e.g. carbonate productivity and anoxic conditions) and ocean current circulation.Supplementary material:Global dataset of Cambrian Epoch 2 (A), Cambrian Epoch 3 (B) and the Furongian Epoch (C) trilobite genera are provided at:http://www.geolsoc.org.uk/SUP18669

The Cambrian-Ordovician transition of the western Mediterranean region (NW Gondwana) is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series. The hiatii are diachronous and involved progressively younger strata along the Gondwanan margin, from SW (Morocco) to NE (Montagne Noire). They can be related to development of a multi-stage rifting (further North), currently connected to the opening of the Rheic Ocean, and concomitant erosion on southern rift shoulders. The platforms of this margin of Gondwana occupied temperate-water, mid latitudes and were dominated by siliciclastic sedimentation, while carbonate factories were only episodically active in the Montagne-Noire platform. The Upper Cambrian is devoid of significant gaps in the southern Montagne Noire and the Iberian Chains. There, the sedimentation took place in a transgressive-dominated depositional system, with common offshore deposits and clayey substrates, and was bracketed by two major regressive trends. The Late Cambrian is also associated with the record of volcanic activity (e.g., in the Cantabrian and Ossa-Morena zones, and the northern Montagne Noire), and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope-related facies associations. Several immigration events are recognized throughout the latest Middle Cambrian, Late Cambrian and Tremadocian. The trilobites show a stepwise replacement of Acado-Baltic-type families (e.g., the conocoryphid-paradoxidid-solenopleurid assemblage) characterized by: (i) a late Languedocian (latest Middle Cambrian) co-occurrence of Middle Cambrian trilobite families with the first anomocarid, dorypygid and proasaphiscid invaders; (ii) a Late Cambrian immigration replacing previous faunas, composed of trilobites (aphelaspidids, catillicephalids, ceratopygids, damesellids, eulomids, idahoiids, linchakephalids, lisariids, onchonotinids, and pagodiids), linguliformean brachiopods (acrotretids, obolids, scaphelasmatids, siphonotretids, and zhanatellids), echinoderms (mitrates, glyptocystitid cystoids, and stromatocystoids), and conodonts belonging to the lower Peltura Zone; and (iii) the subsequent input of new trilobites (asaphids, calymenids, catillicephalids, nileids and remopleurids), which marks the base of the Proteuloma geinitzi Zone, associated with pelmatozoan holdfasts (Oryctoconus), and a distinct input of late Tremadocian conodonts (Paltodus deltifer Zone). The biogeographic distribution of latest Middle and Late Cambrian trilobites supports brachiopod data indicating strong affinities between the western Mediterranean region, East Gondwana (North China/Korea, South China, Australia, and Antarctica) and Kazakhstania during the late Languedocian, which became significantly stronger during the Late Cambrian. This major shift may suggest modification in oceanic circulation patterns throughout Gondwana across the Middle-Late Cambrian transition. (c) 2007 Elsevier B.V. A...

In South America, autochthonous archaeocyathan faunas preserved in Early Cambrian limestones have not been found yet. Nevertheless, a few well‐documented occurrences of these fossils in clasts contained in coarse‐grained rocks of a wide age range have been discovered in recent years. Erratic limestone blocks from the Late Carboniferous–Early Permian Fitzroy Tillite Formation in the Falkland/Malvinas Islands yielded three archaeocyath taxa. Also, seven taxa were reported from archaeocyathan limestone clasts in a metaconglomerate of the Cambro‐Ordovician El Jagüelito Formation in northern Patagonia. In addition, a new record from the Late Carboniferous–Early Permian Sauce Grande Formation diamictites in Sierras Australes, Buenos Aires Province, Argentina, is presented herein. Preservation of this scarce new material is poor, but at least three different taxa can be distinguished. The most likely source of all archaeocyathan limestone clasts found in southern South America is the Shackleton Limestone from the Transantarctic Mountains in East Antarctica. The new record from the Sauce Grande Formation and the inferred clast provenance reinforce the correlation between this unit, the Dwyka Tillite (South Africa) and the Fitzroy Tillite Formation (Falklands/Malvinas), suggesting a very wide distribution of these Antarctic occurrences during the Late Carboniferous–Early Permian Gondwana glaciation (Episode III). Thus, even though being allochthonous, archaeocyaths are emerging as a new key biological feature for Gondwana palaeogeographic reconstructions. Copyright © 2012 John Wiley & Sons, Ltd.

Agnostoid trilobites from the Carlos Rusconi collections in the Museum of Natural Sciences of Mendoza, Argentina, are revised. The agnostoids were collected in the southern Precordillera of Mendoza Province, western Argentina. Revised taxa include Agnostus microcephalus (Rusconi), Lotagnostus (Lotagnostus) peladensis? (Rusconi), Lotagnostus (Lotagnostus) lasherensis (Rusconi), Homagnostus pehuenchensis Rusconi, Kormagnostus seclusus (Walcott), Kormagnostus? beltensis (Lochman in Lochman and Duncan), Hypagnostus parvifrons (Linnarsson), Ptychagnostus cuyanus (Rusconi), Ptychagnostus aculeatus (Angelin), Lejopyge laevigata (Dalman), Tomagnostella exsculpta (Angelin), Diplagnostus planicauda (Angelin), Oedorhachis typicalis Resser, Clavagnostus calensis Rusconi and Clavagnostus repandus (Westergård in Holm and Westergård). Some taxa of uncertain affinities are recognized and new specimens assignated to Lotagnostus and Pseudagnostinae are illustrated. Hypagnostus parvifrons, L. laevigata and C. repandus are reported for the first time in South America. Global correlation with previously described agnostoid faunas indicates that the outcrops range from middle Middle Cambrian to latest Late Cambrian in age.