Big guns of the Cambrian Explosion: Macroskeletal benthic assemblage in the lower Cambrian Stage 2 of the Olenek Uplift, Arctic Siberia

espanolLos estratos basales del Piso cambrico 2 del Olenek Uplift albergan diversos conjuntos de fosiles macroscopicos, que se asemejan mucho a ciertos pequenos taxones esqueleticos documentados en esta seccion y tipicos del Terranoviense. En este caso, la asociacion macroscopica estudiada incluye moluscos helcionelidos, estenotecidos y kharkhanidos, asi como hiolitos de tipo anabaritido y circotecidos. Entre ellos, solo los anabaritidos y algunos hiolitos circotecidos muestran restos de concha calcitica, mientras que la mayoria de los fosiles carecen de exoesqueleto rigido biomineralizado. Por tanto, al menos estos organismos cambricos problematicos habrian alcanzado tamanos macroscopicos (de hasta 35 mm de largo) y estaban cubiertos con conchas calciticas al principio del Pisp cambrico 2. EnglishThe basal Cambrian Stage 2 strata of the Olenek Uplift host diverse assemblages of macroscopic fossils, which closely resemble certain small skeletal taxa early reported from this section and typical for the Terreneuvian Epoch. Herein studied macroscopic assemblage includes helcionellid, stenothecid and kharkhaniid molluscs, and anabaritids and circothecid hyoliths. Among the assemblage, only anabaritids and some citrcothecid hyoliths exhibit relics of calcite shell, whereas most of the fossils reveal no evidence of rigid biomineralized exoskeleton. Hence, at least these problematic Cambrian organisms had reached macroscopic sizes (up to 35 mm long) and were covered with calcite shells at the very beginning of the Cambrian Age 2.