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

摘要

Gogia parslevi 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 oil the basis of fifteen complete or partial specimens and numerous isolated plates. It is characterised by spiralled brachioles. simple epispires, sometimes covered by stereomic doilies or tiny cover plates, and by thecal plates arranged ill subregular circlets. This gogiid population comprises juveniles, advanced juveniles and mature individuals. The material was found in the tipper 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 Caesaratioustian). The germs 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 all early migration from Laurentia. The gogiids are well preserved in two echinoderm Lagerstatten, which, together with other echinoderms, comprise the majority of the fossil fauna. Both levels arc 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 it soft, muddy environment.