Izvestiya of Saratov University.
ISSN 1819-7663 (Print)
ISSN 2542-1921 (Online)


subosculum

Transitory Level of Modular Organization in the Late Cretaceous Hexactinellids (Porifera)

The regularly arranged openings acting as additional oscula – subos­cula – in the skeletal structures of numerous hexactinellids made the basis for recognizing a transient level in those sponge organization: a transition between the unitary and the colonial forms. Unitary, autono­mous and colonial sublevels have been recognized in the transition structures. The morphological diversity of the Late Cretaceous transi­tions was called forth by manifestations of mosaic morphogenesis in the representatives of the Lychniscosa and Hexactinosa orders.