A new microconchid species from the Silurian of Baltica

Abstract

The diversity of Silurian microconchids is still poorly understood. Here, a new microconchid tubeworm species, Palaeoconchus wilsoni, is described from the Silurian (Ludlow) encrusting rugose corals from Estonia (Saaremaa Island) and a brachiopod shell from Sweden (Gotland). In Estonia, the microconchids are a dominant constituent of the encrusting assemblages, associated with cornulitids, Anticalyptraea, auloporids, trepostome bryozoans, hederelloids and enigmatic ascodictyids. It is notable that these Silurian encrusting assemblages are clearly dominated by tentaculitoids (microconchids, cornulitids and Anticalyptraea) which very often co-exist on the same coral host. Morphologically similar microconchids and Anticalyptraea may have exploited a more similar ecological niche than the straight-shelled cornulitids. However, the clear predominance of microconchids over Anticalyptraea in the communities may indicate that this genus was a less effective competitor for food than microconchid tubeworms.