Also known as Gaudyceras (Pachygaudyceras) yokoyamai zone

Where: Sakhalinskaya, Russian Federation (47.2° N, 142.5° E: paleocoordinates 53.5° N, 131.7° E)

• coordinate estimated from map

• local area-level geographic resolution

When: Gaudyceras (Pachygaudyceras) yokoyamai ammonoid zone, Kwakami Group, Early/Lower Santonian (85.8 - 83.5 Ma)

• called Kwakami group; may be misspelling of Kawakami, Gaudyceras (Pachygaudyceras) yokoyamai zone; E. Yazykova (Acta Geologica Polonica, Vol. 54 (2004), No. 2, pp. 273-312), describes Shimuzu 1935 as follows: "this paper was the first detailed documentation of a Cretaceous ammonite zonation in central and southern Sakhalin. It should be noted, however, that there are numerous problems in that paper with regard to age assignment of the succession and to exposed intervals.For instance, no Albian faunas were recorded and Campanian deposits were misdated as Maastrichtian, Turonian as Coniacian, Santonian as Campanian, Danian as Maastrichtian, etc. Later, MATSUMOTO (1959c) noted that, at first glance, the zones proposed by SHIMIZU appeared to compare well to those then known in Europe, but in fact they often conflicted with data obtained during subsequent field work."

• formation-level stratigraphic resolution

Environment/lithology: marine; sandstone and shale

Size class: macrofossils

Primary reference: S. Shimizu. 1935. The Upper Cretaceous cephalopods of Japan, Part I. J. Shanghai Sci. Inst.,sec. II 1(11):159-226 [R. Plotnick/R. Plotnick/R. Plotnick]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 64693: authorized by Roy Plotnick, entered by Roy Plotnick on 12.09.2006

Creative Commons license: CC BY (attribution)