Revision of asterolepidoid antiarch remains from the Ogre Formation (Upper Devonian) of Latvia

摘要

The Frasnian (Upper Devonian) antiarch Walterilepis speciosa was first described in 1933 (as Taeniolepis) on the basis of a single specimen. The newly collected material has allowed the head to be described in a more detail, especially the nuchal and paranuchal plates. Other newly described elements include bones of the pectoral appendages and trunk armour, demonstrating a rather high and short trunk armour. The shape and proportions of the head and trunk armour suggest the attribution of Walterilepis to the family Pterichthyodidae; it is most probably closely related to Lepadolepis from the Late Frasnian of Germany. Whilst W speciosa is endemic to the Latvian part of the Baltic Devonian Basin, the connection to the Rheinisches Schiefergebirge is probably closer than previously presumed. Walterilepis fits into the biostratigraphical column at the same level as Bothriolepis maxima and B. evaldi, indicating the high diversity of antiarchs during Pamusis tune.