ALT Top left: Maps of Morocco with the Atlantic on the left (in blue) and Ordovician outcrops of the Anti-Atlas in yellow. A rectangle around Zagora in a region towards the upper right shows the study area. The inset at top left shows the location on a more general map. On the right, three black and white fossil brachiopod images: top is Rafanoglossa inversa (scale bar bottom right of image is 2 mm); middle is Tarfaya marocana (scale bar bottom left is 2 mm); bottom is Lacunites punctum (scale bar bottom right is 2 mm). Colour photograph at bottom left is a slab containing many specimens of Celdobolus mirandus (horizontal white scale bar to right of image is 5 mm).

ALT Top left: map of Greenland with the fossil outcrops of Upper Ordovician and lower Silurian strata shaded in the north. Bottom, schematic of the stratigraphy of the shallow-water sediments showing the the various localities (numbered) placed according to their approximate geographical position along the ~750km transect line, west to east (left to right). In the upper right quadrant, five examples of significant taxa from this fauna: top row - Tcherskidium tenuicostatum (GGU 254729) and Borealoides balderi (MGUH 34240, holotype); bottom row - Proconchidium schleyi (MGUH 34049), Virgiana hursti (MGUH 34226, holotype) and Kulumbella heimdali (MGUH 34259, holotype). All scale bars represent 10 mm.