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Brachiopods from the uppermost Lower Ordovician of Peru and their palaeogeographical significance

100%

Gutierrez-Marco J. C., Villas E.

Acta Palaeontologica Polonica

2007

tom 52

nr 3

The studied brachiopod assemblages from the uppermost Lower Ordovician beds of Peru are of very low diversity and are among the northernmost known strata of that age in South America. They have been collected at the Carcel Puncco canyon of the Inambari River, near San Gabán in the easternmost Eastern Cordillera. Of the six species described, Euorthisina orthiformis and Paralenorthis immitatrix were already known from the Bolivian outcrops of the same Andean Eastern Cordillera; two species are new: Ahtiella zarelae Villas sp. nov. and Paralenorthis carlottoi Villas sp. nov. The new species of Ahtiella, of late Floian age, represent the oldest record of the genus characteristic of Celtic assemblages. During the early Mid Ordovician the genus migrated eastward from this region into the north margin of proto−Avalonia and after that, in Llanvirn times, into Baltica. During the early Llanvirn Ahtiella also migrated westward reaching the Precordillera Argentina region. Brachiopod faunal affinities suggest that there was a closer proximity of Avalonia with the Central Andean Basin, in similar temperate latitudes, than with the Southwestern European Platform, placed in very high latitude. Paralenorthis does not give any palaeogeographical signal, since it is known from all latitudes and palaeocontinents. Nevertheless, the occurrence of Euorthisina reinforces the Gondwanan signature of the region, since this genus spread during the Arenig throughout the middle latitude belt at the Gondwana margins, although it also colonised sub−polar latitudes, coinciding with the Llanvirn transgression over North Gondwana.

Orthid brachiopods from the Middle Ordovician of the Central Iberian Zone, Spain

81%

Reyes-Abril J., Villas E., Gutierrez-Marco J. C.

Acta Palaeontologica Polonica

2010

tom 55

nr 2

285-308

The present study of a large collection of orthid brachiopods from Middle Ordovician (middle Darriwilian) strata of Spanish regions of the Central Iberian Zone of the Iberian Massif, as well as the type collection of Portuguese species from the same Zone, revealed the occurrence of five genera of the family Orthidae, two of them new, and to which most of the seven previously reported species of Orthis from the same areas can be assigned. Besides the two new genera and species Almadenorthis auriculata Reyes−Abril and Villas gen. et sp. nov., and Gutiorthis incurvata Reyes−Abril and Villas gen. et sp. nov., three further new species are erected: Paralenorthis estenaensis Reyes−Abril and Villas sp. nov., Paralenorthis lolae Reyes−Abril and Villas sp. nov., and Sivorthis calatravaensis Reyes−Abril and Villas sp. nov. Paralenorthis alata and Orthambonites sp. are also identified in the same beds. Orthis noctilio is ascribed to the genus Sivorthis, and the species Orthis lusitanica and Orthis miniensis are restricted to only their type specimens. Orthis duriensisis poorly described and illustrated, its type material missing, and actually it may belong to Sivorthis noctilio. These brachiopod taxa invaded the cold waters of the Afro−South European Gondwanan margin from lower latitudes, coincident with the mid Darriwilian transgression, as they belonged to a family that diversified in temperate and tropical seas during the early Mid Ordovician.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Gutierrez-Marco J. C.

2 Villas E.

1 Reyes-Abril J.

1 2010

1 2007

Wyniki wyszukiwania

Brachiopods from the uppermost Lower Ordovician of Peru and their palaeogeographical significance

Orthid brachiopods from the Middle Ordovician of the Central Iberian Zone, Spain