calcareous algae of the middle east 87 



Lower Jurassic 

 The occurrence of the Liassic Palaeodasycladus in the Lower Musandam of Oman is 

 compatible with the age from other evidence (Hudson & Chatton 1959), but as the 

 alga is so far recorded only from one level it shows no more than as an easterly 

 occurrence of this well-known Mediterranean fossil. 



Upper Jurassic-Lower Cretaceous 



The ranges of various dasyclads in the Middle East at these levels are shown on the 

 chart. Reference to the European literature indicates different local ranges for some 

 of these species. Thus Actinoporella podolica is Portlandian at the Galician type- 

 locality, Portlandian-Valanginian in Switzerland, Portlandian-Hauterivian in Italy, 

 and Valanginian-Aptian in the Middle East. This probably reflects facies-preference 

 along successive Tethyan coasts, partly obscured by some occurrences being pre- 

 served in off-shore debris-facies. It is of course possible that a suite of similarly 

 well-preserved specimens from each locality would permit successional subdivision 

 of the species. The type-material comprises loose, dissociated verticils, whereas 

 most of the other records are from random thin-section material. However, this 

 must await future studies. In association with other microfossils, A. podolica is a 

 useful species in the Middle East, as are most dasyclad remains. Munieria baconica 

 shows a somewhat similar range, with varying local occurrences. By contrast, such 

 species as Clypeina lucasi and C. marteli occur only at the same level in Oman as 

 that of the Algerian types. The European ranges of a dasyclad species, and the 

 details of its Middle East occurrences, will already have been noted under each 

 species-description. 



The algal dating of the Jurassic-Cretaceous contact in the wholly marine Tethyan 

 succession is of some importance. Over large type-areas of western Europe a varying 

 thickness of nonmarine Purbeck-facies strata occurs between undoubted marine 

 Upper Jurassic and Lower Cretaceous. This Purbeckian is conventionally assigned 

 to the Jurassic, though the studies of Donze (1958b) on the Jura area, and Casey 

 (1963) on England, suggest that much of it is Cretaceous (see also Bartenstein, 1965). 

 In southern France, where marine Tithonian is succeeded by marine Berriasian, the 

 two may be distinguished by their ammonite faunas. In many other Tethyan lime- 

 stone successions at this level the absence of ammonites, whether due to their non- 

 occurrence in the fauna or their non-availability as in samples from bore-holes, 

 necessitates estimation of the junction from microfossils in thin-section. The for- 

 aminifera give no clear picture, and tintinnids are confined to a special stratigraphical 

 facies. Dasyclad algae are often abundant ; in my experience, if determined 

 carefully, with a full knowledge of their recorded ranges elsewhere and used in 

 conjunction with non-dasyclad algae such as Permocalculus spp. and various non- 

 algal fossils such as the hydrozoan Cladocoropsis, it is usually possible to give an 

 accurate age-determination. 



Upper Cretaceous 

 The dasyclads of the Middle East Upper Cretaceous are fewer in number than those 



