Acta Palaeontologica Polonica

The aperture and its closure in an Ordovician conulariid

Consuelo Sendino, Kamil Zágoršek, and Zdeňka Vyhlasová

Acta Palaeontologica Polonica 56 (3), 2011: 659-663 doi: http://dx.doi.org/10.4202/app.2010.0028

The conulariids, an enigmatic fossil group believed to be of cnidarian (scyphozoan) affinity, have four−sided, acutely
pyramidal exoskeletons terminated in apertural closures. To date, three main closure types have been recognised in
conulariids (plicated, triangular lappets, and lobate lappets) but the first type is poorly illustrated in the literature. Here we present the first photographic illustration of an unequivocal plicated closure in Metaconularia? anomala, based on study of the rich (1700+ specimens) material from the Upper Ordovician of the Prague Basin. This closure is formed by inwardly folded, triangular lappets centred on each of the four faces, with kite−shaped elements centred on the four corners forming a webbing between the lappets. Plicated closures were evidently rare in conulariids and restricted to a few Ordovician species.

Consuelo Sendino [c.sendino-lara@nhm.ac.uk], Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD; Kamil Zágoršek [kamil_zagorsek@nm.cz], Paleontologické oddělení, Národní muzeum, Václavské nám. 68, CZ - 115 79 Praha 1 (CZ); Zdeňka Vyhlasová [vyhlaska@volny.cz[, Department of Palaeontology, Museum of West Bohemia in Pilsen, Kopeckého sady 2, 301 36 Pilsen (CZ).