Shell ontogeny in radiolarians
Abstract
The ontogeny of the shells in modern and ancient radiolarian species, Acrosphaera cyrtodon were observed by scanning and transmission electron microscopy. The shells of A. cyrtodon were obtained from core samples collected from the Central Indian Ocean Basin at a water depth of 5,300 m. The phylogenatic relationships was based on developmental stages in addition to current evidence that is largely based on morphology of mature shells observed in different geological strata. Several polycystine skeleton forms can be explained as the product of two basic growth patterns bridge and rim growth were observed in the mature skeltons of the fossil and living radiolaria. Using this paradigm of bridge and rim growth another additional form has been identified in fossil and living species, i.e. the central capsules divide by binary fission during froliferation within the colony. However, all these stages of binary fission occurred in early development befor silica deposition. The interpretation of radiolarian abundance and life cycle strategies is based on above parameters
Collections
- Scholarly literature [8843]