Paläontologische Zeitschrift

, Volume 39, Issue 3–4, pp 134–146 | Cite as

Adaptive homoeomorphy in the brachiopods Tetractinella Bittner and Cheirothyris Rollier

  • M. J. S. Rudwick


The Middle Triassic athyraceanTetractinella and the Upper Jurassic terebratellaceanCheirothyris show a close homoeomorphic resemblance in their external shell form. The homoeomorphy is here interpreted as the result of the parallel evolution of an identical adaptive device. Structurally, the homoeomorphy is due to the development of two pairs of long, narrow radial deflections of the commissure, and consequently of two pairs of marginal projections and radial costae on the shell. Functionally, these projections are interpreted as sensory “antennae”, which carried the sensitive mantle edges outwards beyond the rest of the shell, and hence provided the brachiopods with early warning of the approach of potentially harmful agents in the environment.


Jurassic Middle Triassic Growth Line Ventral Valve Dorsal Valve 
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Copyright information

© E. Schweizerbart’sche Verlagsbuchhandlung 1965

Authors and Affiliations

  • M. J. S. Rudwick
    • 1
  1. 1.Sedgwick MuseumCambridgeEngland

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