Conulariids from the Silurian (late Telychian) Waukesha Lagerstätte, Wisconsin

Abstract

ABSTRACT The Silurian (late Telychian) Brandon Bridge Formation, Wisconsin, USA, is renowned for hosting the Waukesha Konservat-Lagerstätte, in which several rare, enigmatic constituents have received detailed taxonomic and taphonomic study. However, more common species from this deposit remain poorly described. This study provides the first systematic description of two conulariid species documented from the Waukesha Konservat-Lagerstätte – Conularia niagarensis and Metaconularia cf. manni – and assesses their general taphonomy and preservation within this deposit. Specimens were examined using a combination of light microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy to assist in taxonomic, taphonomic and compositional analyses. Conulariid specimens display an array of preservational modes, primarily diagenetic phosphatisation and kerogenization, with minor associated pyritisation. This result suggests a taphonomic history involving post-burial demineralisation associated with falling pH conditions, subsequent compression with minimal breakage, and finally diagenetic mineralisation of the compressed thecae by francolite.