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Middle Cambrian gogiid echinoderms from Northeast Spain: Taxonomy, palaeoecology, and palaeogeographic implications

100%

Zamora S., Gozalo R., Linan E.

Acta Palaeontologica Polonica

2009

tom 54

nr 2

253-265

Gogia parsleyi Zamora sp. nov. and Gogia sp. are described from two different echinoderm assemblages, both from the middle Cambrian of the Murero Formation (Iberian Chains, NE Spain). Gogia parsleyi is reconstructed and described on the basis of fifteen complete or partial specimens and numerous isolated plates. It is characterised by spiralled brachioles, simple epispires, sometimes covered by stereomic domes or tiny cover plates, and by thecal plates arranged in subregular circlets. This gogiid population comprises juveniles, advanced juveniles and mature individuals. The material was found in the upper part of the Murero Formation (upper Caesaraugustian–lower Languedocian). Gogia sp. is represented by two almost complete specimens and several isolated plates from the lower part of the Murero Formation (lower Caesaraugustian). The genus Gogia was first described in Western Gondwana from the Languedocian (upper middle Cambrian) of France, but the material from Spain is older and represents the oldest record of this genus in Gondwana, suggesting an early migration from Laurentia. The gogiids are well preserved in two echinoderm Lagerstätten, which, together with other echinoderms, comprise the majority of the fossil fauna. Both levels are derived from obrution deposits produced in calm and open marine conditions, sometimes affected by sporadic storms. Their holdfast morphology suggests that these gogiids were low−tier suspension feeders, living attached to trilobite fragments in a soft, muddy environment.

New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain

88%

Zhuravlev A. Y., Linan E., Gamez Vintaned J. A., Debrenne F., Fedorov A. B.

Acta Palaeontologica Polonica

2012

tom 57

nr 1

A current paradigm accepts the presence of weakly biomineralized animals only, barely above a low metazoan grade of organization in the terminal Neoproterozoic (Ediacaran), and a later, early Cambrian burst of well skeletonized animals. Here we report new assemblages of primarily calcareous shelly fossils from upper Ediacaran (553–542 Ma) carbonates of Spain and Russia (Siberian Platform). The problematic organism Cloudina is found in the Yudoma Group of the southeastern Siberian Platform and different skeletal taxa have been discovered in the terminal Neoproterozoic of several provinces of Spain. New data on the morphology and microstructure of Ediacaran skeletal fossils Cloudina and Namacalathus indicate that the Neoproterozoic skeletal organisms were already reasonably advanced. In total, at least 15 skeletal metazoan genera are recorded worldwide within this interval. This number is comparable with that known for the basal early Cambrian. These data reveal that the terminal Neoproterozoic skeletal bloom was a real precursor of the Cambrian radiation. Cloudina, the oldest animal with a mineralised skeleton on the Siberian Platform, characterises the uppermost Ediacaran strata of the Ust’−Yudoma Formation. While in Siberia Cloudina co−occurs with small skeletal fossils of Cambrian aspect, in Spain Cloudina−bearing carbonates and other Ediacaran skeletal fossils alternate with strata containing rich terminal Neoproterozoic trace fossil assemblages. These finds treated together provide a possibility to correlate transitional Neoproterozoic– lower Cambrian strata around the world. Such a correlation concurs with available isotope and radiometric data and indicates that typical Ediacaran shelly fossils have not crossed the Precambrian–Cambrian boundary.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Linan E.

1 Debrenne F.

1 Fedorov A. B.

1 Gamez Vintaned J. A.

1 Gozalo R.

1 Zamora S.

1 Zhuravlev A. Y.

1 2012

1 2009

Wyniki wyszukiwania

Middle Cambrian gogiid echinoderms from Northeast Spain: Taxonomy, palaeoecology, and palaeogeographic implications

New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain