Smithicyathus cf. lacunosus ( Gürich, 1896 )

Wrzołek, Tomasz, 2007, A revision of the Devonian rugosan phillipsastreid genus Smithicyathus, Acta Palaeontologica Polonica 52 (3), pp. 609-632 : 622

Smithicyathus cf. lacunosus ( Gürich, 1896)

Fig. 8B, C.

Discussion.—Here belong two colonies from the Upper Frasnian set B of Panek, with the highest atypicality indices within the sample of over 70 phaceloid colonies measured. They may represent either morphologically outstanding colonies of Smithicyathus lacunosus , or another species (or two other species, to be exact). The first of them (Fig. 8B) has very thin septa and a very broad dissepimentarium, externally to the periphery of the zone of horseshoe dissepiments. The other (Fig. 8C) is the dimorphic colony with larger and smaller corallites present, the former with broader dissepimentarium, the latter with very narrow dissepimentarium and the occasional replacement of horseshoe dissepiments by peneckielloid ones. Apparently, smaller corallites result from suppression of growth, caused by local re−orientation of corallites’ growth direction from normal, outwardly orientated, with resulting fan−shaped corallites’ arrangement, to inwardly−orientated, with resulting deficiency of available space and suppression of growth of some, but not of all, corallites.