Macro-Borings in Cretaceous Oysters from Drumheller, Alberta: Taphonomy and Paleoecology

Abstract

<p> Macro-borings and other biogenic structures found in Ostrea glabra valves were examined using a dissecting microscope, SEM and X-radiography. Shells were collected from in situ and transported oyster beds of the Bearpaw-Horseshoe Canyon Formation transition (Upper Cretaceous) at Drumheller, Alberta. Emended diagnoses for Entobia, Talpina and Zapfella were proposed and systematic descriptions of these ichnogenera along with Oichnus were done. Repair blisters and partitions apparently formed by the oyster in response to irritations were also described and interpreted. It was confirmed that statistical analysis could differentiate between round holes drilled by naticids and muricids. It was possible to define fossil micro-environments on the basis of an interpretation of taphonomy and paleoecology considered within the sedimentary context.</p>