Pseudolonchodina (Aspelundia) expansa was first used as the nominate species of the basal Llandovery biozone of the Greenland slope facies (Armstrong, 1990). In Latvia, the
Conodonts No conodonts
Green-gray shale Limestone
YU-R YU-Q
YU-P YU-O
YU-N YU-M
YU-L YU-K
81
YU-J
YU-I YU-H Figure 2. Stratigraphic section of Yamaan Us showing carbonate samples processed for conodont recovery. Sample names begin with YU- followed by a letter.
Ps. expansa biozonewas found to correlatewith the upper cyphus to upper leptotheca graptolite biozones that correspond to the late Rhuddanian through early Aeronian (Loydell et al., 2003).