Skip to content Skip to navigation

Article: A phenetic strategy model for dalmanellid brachiopods

Publication: Palaeontology
Volume: 21
Part: 3
Publication Date: July 1978
Page(s): 535 554
Author(s): J. M. Hurst
Addition Information

How to Cite

HURST, J. M. 1978. A phenetic strategy model for dalmanellid brachiopods. Palaeontology21, 3, 535–554.

Online Version Hosted By

The Palaeontological Association (Free Access)


A detailed morphological study, through a sequence of nearshore to offshore sedimentary facies, of the Ordovician dalmanellid Onniella and the Silurian Isorthis, suggests that there is a positive correlation between environment and morphotype. A phenetic strategy model is proposed in which offshore dalmanellid populations are characterized by deep, rounded sulcate shells, V-shaped deep pedicle muscle fields, strong crural fossettes, strongly impressed dorsal adductor muscle fields (i.e. quadripartite), large non-restricted brachial valve sockets, and coarse costellae. By contrast, nearshore dalmanellid populations are characterized by transverse, shallow, non-sulcate shells with U-shaped shallow pedicle muscle fields, weak crural fossettes, weakly impressed dorsal adductor muscle fields, restricted brachial valve sockets, buttressed brachiophores, and fine costellae. There are exceptions to the model but generally the positive correlation, which is explained in terms of functional necessity, has repercussions on previously proposed species phytogenies and their use as biostratigraphic indicators.
PalAss Go! URL: | Twitter: Share on Twitter | Facebook: Share on Facebook | Google+: Share on Google+