| A nearly complete specimen of a hexactinellid sponge has been recovered from Lower Ordovician siliciclastic rocks of the Argentine Precordillera. The material was collected in the upper member of the Los Azules Formation (Sandbian). A new species of the genus Cyathophycus Walcott, C. extendis, is erected. The taxonomic position of the genus is still controversial. Their recent assignment to the family Dictyospongiidae is discussed; Cyathophycus has been considered as a transitional form between protospongiids with simple regular skeletons and dictyospongiids with more complex skeletons. Previous studies have stated that hexactinellid evolution through the Cambrian-Ordovician interval, like other sponge groups at this time, appears to have been based on... |
