Acta Palaeontologica Polonica

Morphology and ontogeny of some Middle Ordovician gonambonitid brachiopods from Baltoscandia

Anna A. Madison

Acta Palaeontologica Polonica 63 (3), 2018: 585-594 doi:

The Volkhovian–Kunda boundary deposits of the Leningrad Region contain two closely related genera, Antigonambonites and Anchigonites. The latter genus was previously known only by valve moulds; here its shell exterior and interior, and ontogeny are described in detail based on the collection of well-preserved disarticulated valves of Anchigonites conulus. Antigonambonites and Anchigonites share similar developmental and morphological features, and ecological strategies including the attachment by cementation by a “pedicle tube” and are thus possibly phylogenetically related. A new diagnosis for the genus Anchigonites and description of A. conulus are provided; other species of Anchigonites are briefly revised. The moulds of outer epithelial cells are described for the first time for the class Strophomenata.

Key words: Brachiopoda, Gonambonitidae, morphology, ontogeny, Ordovician, Russia.

Anna A. Madison [], Borissiak Paleontological Institute of Russian Academy of Sciences, 123, Profsoyuznaya ul., Moscow, 117997 Russia.

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