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Primeiro registo de trilobites no Silúrico de Portugal (Sinclinal de Moncorvo)
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Advisor(s)
Abstract(s)
RESUMO: A ocorrência de fósseis de trilobites em Portugal é conhecida desde há mais de 150 anos, mas permanecia por comprovar a presença deste grupo nas litologias do Silúrico. Reporta-se agora o primeiro registo de trilobites no Silúrico de Portugal, numa sucessão de intercalações de argilitos e calcários da Formação Campanhó do Sinclinal de Moncorvo. As trilobites são raras, estando a associação amplamente dominada por equinodermes scyphocrinitídeos, com cefalópodes nautiloides ortocónicos, tendo ainda sido registado um único fóssil de bivalve, Panenka?, constituindo também o primeiro registo do grupo no Silúrico da região. Do ponto de vista sistemático, foi possível identificar o encrinurídeo Cromus sp. e os phacopídeos Ananaspis? e Denckmannites?. Não obstante a identificação em nomenclatura aberta, o material português apresenta maior semelhança com as espécies-tipo destes géneros, respetivamente Cromus intercostatus, Denckmannites volborthi e Ananaspis fecunda, as três identificadas na Formação Kopanina do Ludlow da Chéquia, sugerindo a mesma idade para os níveis estudados. Os novos dados estreitam a relação deste setor da Zona Centro-Ibérica com as faunas bentónicas silúricas de afinidades boémicas, já reconhecidas no NO de Espanha, Pirenéus, Catalunha e na Zona de Ossa Morena, sendo distintas da restante Zona Centro-Ibérica e semelhantes ao norte de África e Boémia.
ABSTRACT: The abundance of trilobite fossils in Portugal has been known for over 150 years, but the presence of the group in the Silurian remained to be evidenced. Here we report the first record of trilobites in the Silurian of Portugal, in a succession of shales intercalated with limestones belonging to the Campanhó Formation of the Moncorvo Syncline. Trilobites are rare, and the assemblage is largely dominated by scyphocrinitid echinoderms, with orthoconic nautiloid cephalopods and a unique record of the bivalve Panenka?, constituting the first record of the group in the Silurian of this region. From a systematic point of view, it was possible to identify the encrinurid Cromus sp. and the phacopids Ananaspis? and Denckmannites?. Despite the open nomenclature, the Portuguese material is more similar to the type species of these genera, Cromus intercostatus, Denckmannites volborthi and Ananaspis fecunda, respectively, all from the Kopanina Formation from the Ludlow of Czechia, suggesting the same age for the levels studied. The new data strengthen the relationship between this sector of the Central Iberian Zone and the Silurian benthic faunas with Bohemian affinities already recognised in NW Spain, the Pyrenees, Catalonia and the Ossa-Morena Zone, being distinct from the rest of the Central Iberian Zone and similar to North Africa and Bohemia.
ABSTRACT: The abundance of trilobite fossils in Portugal has been known for over 150 years, but the presence of the group in the Silurian remained to be evidenced. Here we report the first record of trilobites in the Silurian of Portugal, in a succession of shales intercalated with limestones belonging to the Campanhó Formation of the Moncorvo Syncline. Trilobites are rare, and the assemblage is largely dominated by scyphocrinitid echinoderms, with orthoconic nautiloid cephalopods and a unique record of the bivalve Panenka?, constituting the first record of the group in the Silurian of this region. From a systematic point of view, it was possible to identify the encrinurid Cromus sp. and the phacopids Ananaspis? and Denckmannites?. Despite the open nomenclature, the Portuguese material is more similar to the type species of these genera, Cromus intercostatus, Denckmannites volborthi and Ananaspis fecunda, respectively, all from the Kopanina Formation from the Ludlow of Czechia, suggesting the same age for the levels studied. The new data strengthen the relationship between this sector of the Central Iberian Zone and the Silurian benthic faunas with Bohemian affinities already recognised in NW Spain, the Pyrenees, Catalonia and the Ossa-Morena Zone, being distinct from the rest of the Central Iberian Zone and similar to North Africa and Bohemia.
Description
Keywords
Trilobites Formação Campanhó Calcários de Scyphocrinites Sinclinal de Moncorvo Campanhó Formation Scyphocrinites limestone Moncorvo Syncline
Citation
Pereira, S., Silvério, G., Lallena, J. C., Moreira, N., Silva, D. & Sá, A. (2025). Primeiro registo de trilobites no Silúrico de Portugal (Sinclinal de Moncorvo). In: Comunicações Geológicas, 2025, vol. 112, Fascículo Especial I, pp. 103-107. https://doi.org/10.34637/kbaj-6651
Publisher
LNEG - Laboratório Nacional de Energia e Geologia