Internal structure of Cambrian vendobionts Arumberia, Hallidaya, and Noffkarkys preserved by clay in Montana, USA

Abstract

Quilted fossils known as vendobionts have remained enigmatic because preserved as unrevealing impressions in sandstone, for example, Arumberia banksi Glaessner & Walter, Noffkarkys storaasli Retallack & Broz, and Hallidaya brueri (Wade) Retallack & Broz from the Ediacaran to Cambrian, Grant Bluff and Arumbera formations of central Australia. These same species are reported here in shaley facies of the Early Cambrian Flathead Sandstone of Fishtrap Lake, Montana. These fossils preserved in three dimensions are infiltrated by clay and confirm that each taxon has distinctive internal chambers reflecting segmentation seen on the surface. Sedimentary structures, petrography and geochemistry of the Montana sediments are evidence that Arumberia, Noffkarkys and Hallidaya lived on supratidal flats of a wave-protected rock-bound estuary unaffected by marine bioturbation, and represent intertidal to supratidal ecosystems widespread from the Ediacaran to Cambrian.