Microconchids (Tentaculita) from the Middle Jurassic of Poland

Abstract

Spirorbid-like worm tubes, identified as microconchids (Tentaculita) on the basis of morphological and microstructural features, were common and occupied a wide array of environments during the Palaeozoic and Triassic. In the Jurassic, however, microconchids were very rare, represented by only one genus, Punctaconchus Vinn & Taylor, 2007, and confined to normal marine settings. In the present paper, the microconchid Punctaconchus ampliporus Vinn & Taylor, 2007, characterised by large punctae penetrating the exterior of the tubes, is described from the Middle Jurassic of the Polish Jura for the first time. Individuals were found encrusting Lower Bathonian oncoliths. Their low abundance and diversity on the oncoliths may reflect poor competitive ability for substrate space leading up to the final extinction of the group in the late Bathonian.