Correlation of upper Bajocian-Bathonian zones in Siberia with the stage standard

The suggestions to transfer the Arcticoceras ishmae Zone from the middle to the lower Bathonian and the Arctocephalites arcticus Zone from the lower Bathonian to the upper Bajocian put forward by some researchers, are critically considered. These suggestions are based on paleontological records from the Sokur quarry near Saratov. Based on paleontological data from Siberia represented in a number of regional ammonite, belemnite, and retroceram zonations, we infer that the proposed zonal subdivision of the Jurassic in the Sokur quarry to be untrue and believe the revision of the correlation of the above-mentioned zones with the stage and zonal standard to be premature because of insufficient argumentation.