Cambrian fauna of the Top Springs Limestone, Georgina Basin

The Top Springs Limestone, a carbonate unit of the northern Georgina Basin, Northern Territory, Australia, has previously yielded only the trilobite Redlichia, indicating an Ordian (early Middle Cambrian) age for at least part of the formation. New collections of trilobites. brachiopods, hyoliths. molluscs and sponges - fifteen species in all - are described here, leading to the possibility that upper parts of the formation may have been deposited during the succeeding early Templetonian stage. The fauna has a clear affinity with that in the Tindall Limestone of the Daly Basin, and to a lesser extent with the Panton Formation fauna of the Ord Basin. The new heleionellid molluscan genus Kutanjia ugalbala and new species Igorella durara are also described.