Article: Porifera and Chancelloriidae from the Middle Cambrian of the Georgina Basin, Australia

Scanning electron microscopy of polished, slightly etched rock surfaces of samples from the Silurian of Gotland, Sweden, revealed the presence of excellently preserved calcareous microfaunas and microfloras. This paper illustrates several morphotypes of calcareous micro-organisms of unknown biological affinity, attributed to the new family Ovummuridae. Specimens of Ovummurus duoportius Minoura and Chitoku, a problematical microfossil, which was first described from the Upper Pennsylvanian of Kansas, USA, were found in addition to comparable micro-organisms attributed to the following new taxa: Minourella gotlandica gen. et sp. nov., Arouxina pluricellata gen. et sp. nov. and Samtlebenella circumcamerata gen. et sp. nov. In addition, a few other problematical micro-organisms, probably belonging to the same family, are described under open nomenclature. The enigmatic microfossils are compared with other known calcareous organisms, their possible biological affinities are discussed, and the different stages of diagenetic alteration and destruction are illustrated.