Acta Palaeontologica Polonica

Some remarks on colony organization in graptolites

Adam Urbanek

Acta Palaeontologica Polonica 23 (4), 1978: 631-635

Implications of the presence of perithecal membrane for understanding the degree of integration of graptoloid colonies is discussed. In contrast to Kirk's (1975) opinion that graptoloid colonies can be thought of as a kind of superindividual,
a view is advanced that most of morphogenetic functions were delegated to particular zooids. The share of common colonial struotures is too small to consider graptoloid colonies as single individuals. Irregular and localized secretion
speaks against the concept of rhabdosome being a preciselly controlled counting device.

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