TAXONOMY AND PALEOECOLOGY OF THE MOLLUSK PTEROTHECA FROM THE ORDOVICIAN AND SILURIAN OF SCOTLAND

A large sample of the bizarre bellerophontiform mollusc Pterotheca fro m the Upper Llandovery Wether Law Linn Formation in the Scottish Pentl and Hills shows marked polymorphic asymmetry. A survival strategy that presents to a predator a mosaic of different search images is suggest ed to account for the marked variability of the Pterotheca morphology. Multivariate comparisons with Pterotheca mullochensis from the Llando very of Girvan, P. simplex from the Caradoc of Girvan, P. cf. simplex from the Caradoc of the the Northern Belt of the Southern Uplands and P. aff. mullochensis fi om the Llandovery in the Pentland Hills have h elped clarify the morphological differences between these groups. A ne w species, Pterotheca trimerelloides, is established for the specimens from the Pterotheca beds in the Wether Law Linn Formation.