Acta Palaeontologica Polonica

Shell structure of the entomozoaceans: allegedly planktonic ostracodes of the Palaeozoic

Ewa Olempska

Acta Palaeontologica Polonica 36 (4), 1991: 373-398

The prominent external ornamentation of the entomozoacean shells arises from the thin outer layer. The much thicker and structurally complicated inner layer is rarely well preserved. Three microstructural types of the inner layer are recognized: (1) poorly calcified with residual remnants of the original organic matter, (2) better calcified with oval in transverse section cavities that possibly were originally empty, or filled with an organic matter, longitudinal canals, (3) heavily calcified, in some specimens with sparite-filled remnants of cavities, which may represent only artifacts of recrystallization. The outer layer may correspond to the epicuticle and the inner layer to the endocuticle of Recent ostracodes. A hinge, slight left over right valve overlap, and marginal sculpture are identified for the first time in
Famennian entomozoaceans. The mode of life remain unknown. Richterina (Fossirichterina) uffenordeae sp. n. and R. (R.) goodayi sp. n. are proposed.

Key words: Ostracoda, Entomozoacea, Late Devonian, shell structure, morphology, mode of life.

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