The oldest known bryozoan: Prophyllodictya (Cryptostomata) from the lower Tremadocian (Lower Ordovician) of Liujiachang, south‐western Hubei, central China

Abstract

A new cryptostome bryozoan, Prophyllodictya simplex sp. nov., is described from the Nantzinkuan Formation (Lower Ordovician, lower Tremadoc) of Liujiachang, central China. This antedates the previously oldest known bryozoan by several million years. Colony morphology and the phylogenetic position of Prophyllodictya within Cryptostomata are explored. Phylogenetic analysis suggests that Cryptostomata (except Prophyllodictya) can be divided into two major groups, and that Prophyllodictya occupies a basal position in the cryptostome tree, which accords with its simple morphology and antiquity. A close relationship is evident between bryozoans from the South China palaeoplate and those from Baltica.

Diversity dynamics of Ordovician Bryozoa

“…; Ma et al . ). The start of the diversification of bryozoans in the late Darriwilian coincided with the beginning of the global flooding, which lasted at least until the end of the Sandbian (e.g.…”

“…Taylor & Ernst ; Ma et al . ). The records of Cambrian bryozoans presented recently (Landing et al .…”

“…The oldest known bryozoans are ramose (branching) cryptostome colonies from the lower Nantzinkuan Formation, lower Tremadoc (Ma et al . ). Slightly younger deposits of the Fenxian Formation, South China, contain ramose and encrusting to dome‐shaped Trepostomata (Xia et al .…”

“…Ptilodictyines appear very early ( Prophyllodictya from the Tremadoc of China; Ma et al . ). This group diversified strongly during the Ordovician and Silurian, but diminished significantly during the Devonian.…”

“…; Ma et al . ). The majority of extant bryozoans occur within littoral and sublittoral zones; however, few species were recorded from the deep sea.…”