поздний мел

Morphogeneses of the Late Cretaceous Guettardiscyphia (Porifera, Hexactinellida)

Authors: Pervushov E. M.

Guettardiscyphia skeletons are peculiar for thin walls and highly dense apo- and prosopores. Wall mobility was conductive to formation of conical lobate skeletons of various, occasionally geometrically regular outlines. Substantial number of fossil samples from variously composed rocks from all the Upper Cretaceous intervals has made it possible to trace skeleton transformations in sponge ontogenesis and depending on their environmental conditions.

Regenerative Capabilities in the Late Cretaceous Hexactinellids (Porifera, Hexactinellida)

Authors: Pervushov E. M.

Partial and complete regeneration phenomena, cases of skeleton habitus restoration have been recorded in representatives of the Late Cretaceous hexactinnelids. Regeneration incidences are in many ways associated with the ability of silicon-producing cells responsible for constructing skeleton-generating elements, spicules, to transform, to rearrange their functions in response to the changes of the organism position on the substrate surface and/or upon the changes of the aquatic environment parameters.

Colonial Level of Modular Organization in the Late Cretaceous Hexactinellids (Porifera). Genuine Colonies

Authors: Pervushov E. M.

Tendencies of morphogenesis in the Late Cretaceous modular forms contributed to formations of complexly structured secondary (genuine) colonies. Skeletons of genuine colonial sponges differ not just in numerous and diversely arranged equivalent oscula-carrying modules, but in the presence of the module connecting elements – junctions, as well. Characteristic elements of genuine colony skeletons – ostia – have been recognized between the modules and the junctions.

Neogenesis in Structure of Skeletons of Late Cretaceous Sponges Contributed to the Formation of Polyosculumic Forms

Authors: Pervushov E. M.

Arterial directions in formation of module organization of skeleton hexactinellids are caused by vegetative forms of reproduction. It is supposed that some tendency of selection of protozoa module forms can be traced in morphogenesis of separate generic types of late Cretaceous sponges. The concept “polyosculumic„ sponges is considered in vast context personally in reference to skeletons with some osculumics formed in the result of partial regeneration of organism

The Late Cretaceous Deposits of Potassium Soils at the Gremyachinsk Field

Authors: Akhlestina E. F., Moskovsky G. A.

The authors consider the compound of the late cretaceous deposits opened up in the bore hole number 13, 62 at the Gremyachinsk field of the potassium soils in the Volgograd region. According to the sediment basins evolution from the epicontinental basins (cenoman, turon-cognacian) to the subpelagic basins (cenonian) the lithotipe which form in the late cretaceous level the regular repeated layers of the terrigenous, carbonate, argillaceous-siliceous deposits are characterized

Colonial Level of Modular Organization in the Late Cretaceous Hexactinellids (Porifera). Primary Colonies

Authors: Pervushov E. M.

In the structure of modular organization of the Late Cretaceous hexactinellid sponges, the terminal position is assigned to colonial forms, with skeletons peculiar for complex, intricate structures. Primitive (primary) and genuine (secondary) colonies have been revealed. Skeletons of the primary forms, generally with multiple numbers of equivalent modules and oscula, differ morphologically from the genuine colonies in undeveloped module connecting elements, such as junctions and wall closures, and in the lack of ostia

 

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