Early and Middle Cambrian trilobites from Antarctica

Abstract

Eight trilobite faunules ranging in age from Early Cambrian to late Middle Cambrian have been recovered from fossiliferous moraine boulders at Mount Spann in the northeastern Argentina Range, Antarctica. One of the late Middle Cambrian faunules from Mount Spann and one additional Middle Cambrian faunule were collected in place in the lowermost part of the Nelson Limestone of the Neptune Range. Badly deformed and slightly metamorphosed Middle Cambrian trilobites from the Harold Byrd Mountains represent a probable tenth faunule. Almost all trilobites in these faunules are close relatives of Australian, Chinese, or Siberian forms. There are no significant relations between any of the faunules and the Cambrian trilobites of South or North America. Within Antarctica, the areas of the Neptune Range and possibly also the Harold Byrd Mountains were the last to be inundated by transgressing Cambrian seas. Limestones in the Argentina Range at the Weddell Sea end of the Transantarctic Mountains, and the Shackleton Limestone at the Ross Sea end of the mountains, are considerably older than the oldest limestones in the Neptune Range.