SIR-The recent note by Debrenne & Lafuste (1979) is a welcome warning that an occurrence of crystal aggregates which have been mistaken for fossils can have unwarranted consequences for stratigraphy. The authors were apparently unaware of wider implications of their observations. When the paper on Buschmannia (Kaever & Richter, 1976) appeared, I informed the senior author that his fossils were not Archaeocyatha but that similar objects had been described as red algae (Praesolenopora, etc.) from the Late Precambrian of China by Tsao & Liang (1974). Professors Kaever and Oekentorp (University of Miinster) kindly lent me the original material of Buschmannia and this was later supplemented by further specimens collected by Dr W. Hegenberger (Geological Survey of Southwest Africa) at Farm Griinental 151, Windhoek District, from the Griinental Member, Kuibis Subgroup, Nama Group. Lian & Tsao (1976) discussed additional' red algae' from the Sinian of China, extending their stratigraphic range downward to the Kunming 'Series'. Tsao & Zhao (1978) described further 'Coralliniaceae' from Sichuan and adjoining areas. In 1978 Dr M. R. Walter and Dr M. J. Muir (Bureau of Mineral Resources, Canberra) brought to my notice a paper (Walker et al. 1977) where carbonate pseudomorphs after gypsum and anhydrite were described from the Middle Proterozoic of Australia. Drs Walter and Muir, having studied the literature on 'Buschmannia' and 'Praesolenopora', 'Manicosiphonia', etc., concluded that they were not organic remains but crystal pseudomorphs. In the meantime my attempts to verify the algal morphology of the supposed fossils had failed. Having ascertained the same facts as Walter and Muir (and, as we now know, at the same time independently Debrenne), I informed (August 1978) Professor Kaever and Dr Hegenberger that Buschmannia is a pseudofossil. Dr Hegenberger replied that he had originally in the field considered his finds as crystal aggregates. He stressed the significance of the occurrence of evaporite minerals for the interpretation of the conditions of sedimentation of the Buschmannsklippe Formation. From a palaeoecological viewpoint it is interesting that in the Upper and Middle Proterozoic of China (Tengying and Kunyang Groups of the Sinian) they occur in close association with stromatolites, indicating that their environment was locally hypersaline. The relations of the Buschmannsklippe Formation to the Nama Group are no more ' difficult to establish' (Debrenne & Lafuste, 1979) than other Precambrian correlations but on the contrary seem well established (see Martin, 1965, pp. 29, 106, 114-15, 117, 119-20; Hartnady, 1978, Table 13). The identification of the Nama fossils described by Haughton as Archaeocyatha was shown many years ago (Glaessner, 1963, p. 113) to be based on a misinterpretation and this was confirmed recently (Glaessner, 1978). Neither are the Cribricyatha, which are represented in the Nama Group by Cloudina Germs, Archaeocyatha. Hill (1972) listed them under 'Phylum uncertain, probably not Archaeocyatha' while my re-investigation of Cloudina confirmed the view which was first considered by Germs (1972) that they are polychaete worm tubes. The affinities of Cloudina with the Cribricyathacea which are admitted by Debrenne & Lafuste (1979, p. 144) do not indicate a Cambrian age of the basal Nama as some authors have claimed. The survival of some groups of animals on some taxonomic level from Precambrian to Early Cambrian is to be expected by those who do not accept catastrophist views (Glaessner, 1976, p. 270). The top of the Nama Group is probably Lower Cambrian but that is still being investigated. The latest published statement on the age of the basal part (Kroner, 1978, p. 209), 'is that the Kuibis Formation appears to be very late Precambrian in age' (see also Hartnady, 1978, p. 151-4). As Debrenne & Lafuste have stated, this is in agreement with palaeontological evidence, after the exclusion of pseudofossils and other erroneous conclusions.
[1]
F. Debrenne,et al.
Buschmannia roeringi (Kaever & Richter, 1976) a so-called archaeocyatha, and the problem of the Precambrian or Cambrian age of the Nama System (S.W. Africa)
,
1979,
Geological Magazine.
[2]
M. Muir,et al.
Evidence of major sulphate evaporite deposits in the Proterozoic McArthur Group, Northern Territory, Australia
,
1977,
Nature.
[3]
P. Richter,et al.
Buschmannia roeringi n. gen., n. sp. (Archaeocyatha) aus der Nama-Gruppe Südwestafrikas
,
1976
.
[4]
M. Glaessner.
Early Phanerozoic annelid worms and their geological and biological significance
,
1976,
Journal of the Geological Society.
[5]
G. Germs.
New shelly fossils from Nama Group, South West Africa
,
1972
.
[6]
Raymond C. Moore.
Treatise on Invertebrate Paleontology
,
1950
.
[7]
M. Glaessner.
Re-examination of Archaeichnium, a fossil from the Nama Group
,
1978
.
[8]
Yuwu Lian,et al.
Biostratigraphic significance of stromatolites and red algae from the Sinian Subera of China
,
1976
.