Cornulitid tubeworms from the Upper Ordovician Agüeira Formation of northwestern Spain

Two cornulitid species are described herein from the Late Ordovician of Spain. These specimens support the view that there is no reliable evidence for free-living tentaculitids in the Late Ordovician of Spain. The Spanish cornulitids are best classified as secondarily free, solitary, soft-bottom dwellers. The prominent annuli of the Spanish cornulitids presumably had a stabilizing function, helping them maintain their preferred position in soft sediment. The small size of Spanish cornulitids could result from an adaptation to restricted food resources, although phylogenetic or ontogenetic explanations are also possible. The Spanish cornulitid fauna most closely resembles others from Gondwana, especially those from Sardinia.