Article: The evolutionary interpretation of the Foraminiferida Arenobulimina, Gavelinella, and Hedbergella in the Albian of north-west Europe
Arenobulimina macfadyeni Cushman is suggested as the parent stock from which A. chapmani Cushman arose, probably around the Middle-Upper Albian boundary. A. chapmani gave rise to A.frankei Cushman in the varicosum Subzone, which in turn gave rise to A. truncata (Reuss) in the auritus Subzone. A. sabulosa (Chapman) also appears in the auritus Subzone. A.frankei, not A. sabulosa, is suggested as the parent stock from which Flourensina intermedia Ten Dam evolved in the upper Stoliczkaia dispar Zone, whilst the extinction of A. chapmani at this level is followed by the appearance of A. advena (Cushman).The variations in test morphology of Gavelinella intermedia (Berthelin) are discussed. This species is suggested as the parent from which G. rudis (Reuss) and G. cf. baltica Brotzen arose in the Middle Albian. Both G. cenomanica (Brotzen) and G. baltica Brotzen arose from G. intermedia in the varicosum Subzone and S. dispar Zone respectively.Hedbergella infracretacea (Glaessner) is suggested as the primitive Lower Cretaceous species from which H. delrioensis (Carsey) and H. planispira (Tappan) arose probably in the Aptian. Their intergradation in the Lower Albian is discussed. H. infracretacea, which became extinct around the rostratum-perinflatum Subzone boundary, possibly gave rise to H. brittonensis Loeblich and Tappan in the auritus Subzone.