Nerinea

Abstract: Species of the dinoflagellate cyst genera Komewuia and Wanaea are well represented in surface and subsurface, Upper Jurassic strata of coastal Tanzania. One new species of Wanaea, W. tendaguruensis, is described from the Trigonia smeei Bed of the Tendaguru Formation in the Mandawa Basin; it appears to be a useful index of the Kimmeridgian. Wanaea clathrata, W. spectabilis, and W. talea are rare to common constituents of the Oxfordian strata of the middle part of the Bagamoyo Formation in the Ruvu Basin. Komewuia glabra, characteristic of the Kimmeridgian-Tithonian in the southern hemisphere, is recorded from the offshore Kipatimu Formation and from the Trigonia smeei Bed. The Kipatimu Formation was previously dated as Early Cretaceous, but is now considered Late Jurassic due to its content of K. glabra. The informally designated Komewuia sp. A occurs sporadically in the Nerinea Bed (Oxfordian-Kimmeridgian) of the Tendaguru Formation. The species documented herein have short stratigraphic ranges in the Upper Jurassic of coastal Tanzania and are thus potentially useful for regional biozonation and correlation.

Abstract: A description is here given of gastropods from the genus Fibuloptygmatis occurring in the Upper Jurassic deposits of the Mesozoic margin of the Holy Cross Mts and of their life environments. After discussing the taxonomic position of the above genus it has been included into the super-family Itieriacea.·The suggestion advanced by Cox (1949) regarding the change of the type species of the genus Nerinea has also been given some consideration.

Abstract: The Cretaceous chaetetid sponge Acanthochaetetes huauclillensis Sanchez-Beristain and Garcia-Barrera is reported for the first time from the Aptian–Cenomanian Khalsi Formation, Ladakh Himalaya, India. Its low- to high-domical growth form could suggest an adaptation to either an environment with constant sedimentation rates, or to an irregular substrate. However, these growth forms also may indicate an absence of important environmental/sedimentological changes during the lifespan of the sponges. In addition, the growth form of this species suggests a calm, non-turbulent, reef-like microenvironment. Along with the other faunal assemblages, such as the rudists, corals, and the gastropod Nerinea, A. huauclillensis indicates a tropical to subtropical shallow marine carbonate platform setting. This new finding extends its stratigraphic range from the upper Hauterivian to the Aptian–Cenomanian interval in the eastern Tethyan realm.