A new Middle Cambrian hexactinellid, Ratcliffespongia wheeleri, from western Utah, and skeletal structure of Ratcliffespongia

Abstract

A single specimen of Ratcliffespongia wheeleri n. sp. from the upper part of the Middle Cambrian Wheeler Shale in the Drum Mountains of western Utah shows two distinct skeletal layers in the limonite-replaced fragment. The probable inner layer has large, circular to elliptical parietal gaps, some of which are aligned horizontally(?); gaps are outlined by long rays of hexactine-based spicules in irregular orientation and spacing. The probable outer layer has several ranks of stauracts in regular reticulation and ranking, all at approximately 45 degrees to the probably horizontal direction. The specimen is part of a probably shallow turbidite-transported assemblage from the margin of the House Range embayment.