WATERWAYS FORMATION: THE INFLUENCE OF PREDATION ON TURNOVER IN DEVONIAN CONCAVO-CONVEX BRACHIOPODS
The Waterways Formation (Givetian-Frasnian, Devonian, Western Canada Sedimentary Basin) of Alberta captures the critical interval in time during which productidines begin to replace strophodontoids, and both groups are present within Waterways communities. Within the Waterways, strophodontoids, common in the Calumet Member, are replaced through time by productidines, which are more common in the Moberly Member. The most abundant productidine is Praewaagenoconcha n. sp., which was one of the oldest productidine species in North America to have spines on both valves. Praewaagenoconcha spines are arranged in dense concentric rows and the spines of Waterways specimens are also frequently organized on strong rugae. Both repair frequency (a proxy for crushing predation) and drilling frequency on strophomenates were significantly greater in the Moberly than in the Calumet, suggesting that predation may have been an additional factor facilitating faunal turnover during the Waterways, and supporting the hypothesis that the replacement of strophodontoids by productidines through time may have been influenced by predation.