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Synopsis The palaeoecology of some of the species of productid brachiopods which occur in the limestones and shales of Trearne quarry is discussed. The limestones, some of which are peri-reefal, carry a more diverse productid fauna than the shales but the density distribution is not related to rock type. Smaller species occur in the shales which tend locally to develop a high density, mono-specific, Antiquatonia insculpta (Muir-Wood) community. Statistical analysis of orientation data shows that A. insculpta and Pugilis scoticus (J. Sowerby) lived with the visceral disc in a subvertical position and with randomly trending hinge-lines. A. insculpta lived with its hinge-line plunging at 20° to the horizontal while P. scoticus lived with its hinge-line in at least two positions: one plunging at 20° to the horizontal and the other horizontal. Such infraspecific versatility makes generalisations about the living positions of productids suspect.
Shiells et al. (Thu,) studied this question.