Silurian inarticulate brachiopods from Poland

A new record of the phosphate microbrachiopod genus Acrotretella lreland, 1961 from the Lower Ordovician of the Baltic syneclise, in north-east Poland is the oldest known species of the genus. Acrotretella goldapiensls sp. n. co-occurs with conodonts in shallow-water facies of Late Llanvirn age. The new data from Poland extend the statigraphical range of the genus from the Llanvirn to the middle Silurian (Ludlow); during the later Ordovician and Early Silurian Acrotretella apparently migrated westwards to sequentially occupy shallow-water facies on the palaeocontinents of Baltoscandia (Poland and Sweden), Avalonia (England), Laurentia (North America) and Australasia (Australia) with relatively little morphological change.