Odhner (1930) and Hsü (1935) erroneously dated
the sediments of the Gongkang Formation as Pliocene.
They regarded the rich mollusc assemblage as closely
related to the superficially similar fauna of the former
Levantine Stage of Slavonia (Croatia, Bosnia, Serbia;
see Harzhauser & Mandic 2008 for discussion of the
viviparid fauna of Lake Slavonia), and thus determined
a Pliocene age. Today, the Nanning Basin is drained by
the Yong River, and is thus part of the southern catchment
area of the Pearl River.
The gastropod fauna that yielded the specimens described
herein was discovered in a construction trench
near the city of Santang, which is located ca 2 km to
the northeast of Nanning (Fig. 2A; N 22°52.47’, E
108°24.72’). The pit exposed a somewhat more than 6
m thick succession of the Gongkang Formation which
consisted of well-bedded mud- and siltstones of different
colours (Fig. 2B). The gastropods are derived from
different levels in the section (Fig. 2B), and the two
species detailed herein do not co-occur in the same
horizons.
Material and methods