Data from: Pterotheca (Gastropoda) from the Telychian (Silurian) Xiushan formation of South China: Taxonomy, paleoecology and paleogeography

Pterotheca Salter, 1853 is an unusual but readily identifiable
bellerophontoid gastropod that occurs in the Upper Ordovician through to
the Llandovery of the lower Silurian in many parts of North America and
Europe. Recently, a large collection of Pterotheca was obtained for the
first time from the Xiushan Formation of middle Telychian (Llandovery) age
in the Hunan Province of South China. This is also the first record of the
genus in the low-latitude peri-Gondwanan region. Based on the collection,
two new species of Pterotheca, i.e. P. yongshunensis n. sp. and P.
xiushanensis n. sp., were identified and described herein. The morphologic
analysis suggests that close relatives of these new species may be
Pterotheca species from the Telychian of Scotland. The new species show
continuous variations of marginal apex to submarginal apex, implying that
one of the Pterotheca species may be ancestral to the Devonian Aspidotheca
Spriesterbach, 1919. The Pterotheca species from South China possibly
lived a slowly crawling life on a soft substrate, feeding on algae and/or
detritus, and were adapted to a shallow-water setting with substantial
terrigenous input. Given that all the known Silurian Pterotheca species
occurred in siliciclastic settings and most of which represent sea-level
fall and lowstand periods, we demonstrate that geographic isolation and
enhanced ocean circulation during the early Silurian regression
facilitated the speciation of Pterotheca globally, the connection of sea
pathway during the Rhuddanian transgression after the end-Ordovician
glaciation could have led to the primary dispersal of Silurian Pterotheca.