PALEOBIOGEOGRAPHICAL IMPLICATIONS OF ANOMURAN MICROCOPROLITES FROM THE WALLOWA TERRANE: WALLOWA MOUNTAINS, OREGON,USA

Microcoprolites of Anomuran crustaceans are known to have been widely distributed during the late Triassic. Having been described in Triassic limestone of Europe, Africa, North and South America, and Japan; these fecal pellets are evidence of the global distribution of the organisms that produce them. Anomuran crustaceans are infaunal burrowers, and are indicative of shallow water tropical to subtropical environment. Described here are microcoprolites from the Martin Bridge Formation of Wallowa terrane in northeastern Oregon, USA. The occurrence of Palaxius salataensis, Parafaverina? sp, and a third species perhaps endemic belonging to the genus Palaxius; add to our knowledge of the paleobiogeography of the late Triassic. The presence of island arcs in the Panthalassic Ocean no doubt provided shallow water environments and geographic isolation necessary for endemic species to develop in some of the areas studied. However, the fact that the species Palaxius salataensis is so globally distributed suggests that at least some of the organisms that produced these fecal pellets achieved widespread distribution through migration during their larval stage.