Rodolfo Gozalo

The Cambrian of the Iberian Peninsula: An overview

This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups.

Biostratigraphy and palaeobiogeography of the Cambrian genusHipponicharion (Ostracoda)

The bradoriid genusHipponicharionMatthew, 1886 is one of the oldest known Cambrian ostracods. Until now, five species have been documented and another three taxa have been tentatively assigned to one or another species.Hipponicharion has been recorded from Poland, Germany, Morocco as well as from Canada and Great Britain.Hipponicharion hispanicum n. sp. represents the first Cambrian ostracod documented from Spain.Hipponicharion taidaltensis n. sp., formerlyH. aff.geyeriHinz-Schallreuter, 1993 andH. elickii n. sp., formerlyH. cf.eos sensuElicki, 1994 have also been restudied in this paper.Hipponicharion seems to be restricted to the Acadobaltic Province sensuSdzuy (1972). The systematic relationships of the Bradoriida, which is controverse, is briefly outlined, emphasizing close affinities to the Ostracoda.KurzfassungDie GattungHipponicharionMatthew, 1886 gehört zu den ältesten kambrischen Ostrakoden. Bisher wurden fünf Arten nachgewiesen und drei weitere Taxa aus anderen Gattungen wurden der einen oder anderenHipponicharion-Art zugewiesen. Die Gattung selbst ist sowohl aus Polen, Deutschland und Marokko als auch aus Nordamerika und Großbritannien bekannt. MitHipponicharion hispanicum wurden erstmals kambrische Ostrakoden in Spanien nachgewiesen.Hipponicharion taidaltensis n. sp., vorherH. aff.geyeriHinz-Schallreuter, 1993 undH. elickii n. sp., vormalsH. cf.eos sensuElicki, 1994 wurden im Rahmen dieser Arbeit revidiert. Die gegenwärtig sehr kontrovers diskutierten Verwandtschaftsbeziehungen der Bradoriida werden kurz erläutert, wobei die engen Beziehungen zu den Ostracoda betont werden.

A new occurence of the genus Tonkinella in northern Spain and the Middle Cambrian intercontinental correlation

The genus Tonkinella is a typical polimeroid trilobite in lower Middle Cambrian rocks from Vietnam, Canada, U.S.A., India, Korea, Siberia, China and Argentina. It has recently been found in the Mediterranean region (Iberian Chain, northeastern Spain). In this paper we refer the finding of Tonkinella aff. breviceps in the Leonian (lower Middle Cambrian) of the Cantabrian Mountains (northern Spain), analysing its stratigraphical position, fossil assemblages, biochronology and utility for intercontinental correlation. The presence of this taxon allows us to make a more accurate correlation between the Middle Cambrian biochronological scales of Laurentia, the Mediterranean area and China.

The first record of Dinesus (Trilobita, Dinesidae) in the Cambrian of the Mediterranean region

An important problem facing inter-regional correlation in the Cambrian is the scarcity of shared taxa between different palaeogeographic domains. Currently, species of the Corynexochida are proposed as tools to define the base of Cambrian Series 3. However, few Mediterranean Corynexochida species are known. A specimen of Dinesus truyolsi comb. nov. from the middle Cambrian of Spain represents the first record of this genus in the Acadobaltic province. Erbia and Tingyuania are accepted as junior subjective synonyms of Dinesus, and we now recognize 22 species within this genus. Dinesus has been found previously in lower to middle Cambrian strata of Australia, Russia, Kazakhstan, North America and China providing the potential for improved global correlation for this interval.

The middle lower Cambrian (Ovetian) Lunagraulos n. gen. from Spain and the oldest trilobite records

The type material of Agraulos antiquus Sdzuy, 1961 from the La Herreria Formation, northern Spain, is revised together with additional material and included in the new genus Lunagraulos . The stratigraphical range of Lunagraulos antiquus (Sdzuy, 1961) – occurring below that of the trilobite species of the genera Lunolenus , Metadoxides and Dolerolenus in the type locality of Los Barrios de Luna in the province of Leon, northern Spain – and the accompanying ichnofossil assemblage demonstrate an Ovetian age (lower part of Cambrian Stage 3, currently being discussed by the International Subcommission on Cambrian Stratigraphy) for this species. Moreover, the trilobite Lunagraulos tamamensis n. gen. n. sp. is found in the Tamames Sandstone near the village of La Rinconada in the province of Salamanca, central Spain. The biostratigraphical position of this new taxon and its accompanying ichnoassemblage is also analysed and assigned to the lowermost Ovetian Stage. The genus Lunagraulos is therefore the oldest agraulid found in the fossil record. The exceptional presence of Lunagraulos in a marine coarse siliciclastic succession – a facies rather typical for the ichnofossils Cruziana and Rusophycus , some of the oldest signs of trilobite activity – suggests that first trilobite representatives may have inhabited high- to middle-energy, marine environments. This hypothesis may also explain both the taxonomic and biostratigraphic heterogeneity of the first trilobite genera appearing across the world, due to preservation problems in this type of facies. Comparison of the Lunagraulo s biostratigraphy with other coeval Spanish fossil assemblages allows us to propose its intercontinental correlation with the oldest records of currently known trilobites.

Bradoriid Arthropods from the Lower-Middle Cambrian of Scania, Sweden

Three species of bradoriid arthropods from the lower to middle Cambrian transitional interval of Scania, southern Sweden, are described and illustrated: Beyrichona tinea from the top of the traditional lower Cambrian (Gislöv Formation; Ornamentaspis? linnarssoni Zone), and Hipponicharion eos and Alutella sp. from the basal portion of the traditional middle Cambrian (lowermost part of the Alum Shale Formation). The bradoriid fauna compares most closely with others previously described from western and eastern Avalonia (New Brunswick and England). The record of B. tinea suggests a correlation between the “Protolenus Zone” (Hupeolenus Zone) of western Avalonia and the O.? linnarssoni Zone of Scandinavia. Hipponicharion eos appears to be a fairly long-ranging species as it has previously been recorded from upper lower Cambrian or lower middle Cambrian strata in New Brunswick, Poland, and probably Sardinia. The record of H. eos from the lowermost part of the Alum Shale Formation suggests that this largely unfossiliferous interval in the Scanian succession is not younger than the Acadoparadoxides oelandicus Superzone. The genus Alutella has not previously been recorded from the Acado-Baltic Province.

Paradoxides brachyrhachis Linnarsson, 1883 versus Paradoxides mediterraneus Pompeckj, 1901: a problematic determination

A revision of paradoxidid trilobites reveals that previous identifications of specimens from Sardinia and Spain as the Nordic trilobite species Paradoxides brachyrhachis Linnarsson, 1883, are mistaken. The southern species, occurring also in France, is here referred to Eccaparadoxides mediterraneus (Pompeckj, 1901). Main differences are seen in the preocular field, pleural furrow and pygidium. The species P. brachyrhachis is referred with question to the genus Mawddachites Fletcher 2007.

A blind trilobite with Baltic affinities from Cambrian Series 3 of the Iberian Chains, Spain, and its stratigraphical and palaeobiogeographical significance

Three cranidia of a conocoryphid trilobite are described from the lower Caesaraugustan Regional Stage (upper part of provisional Cambrian Stage 5 within Cambrian Series 3) in the Iberian Chains, Spain. The material is from the upper part of the Mansilla Formation and the base of the overlying Murero Formation. It closely resembles Bailiella tenuicincta (Linnarsson, 1879), which has previously been described from the Ptychagnostus gibbus (Cambrian Stage 5) and lower P. atavus zones (lower Drumian Stage) of Baltica (Sweden and Bornholm), and from the P. atavus Zone of West Avalonia (Newfoundland). The record of B. cf. tenuicincta from the Mediterranean margin of West Gondwana provides additional evidence for considering the Acado-Baltic region a discrete biogeographical province, at least during the Cambrian 5 and Drumian ages.