Intraspecific competition in Guadalupian fasciculate rugose coral clusters (Hawasina Nappes, Oman Mountains)

Guadalupian (middle Permian) reef blocks of the Al Jil and Bai'd formations (Hawasina Nappes, Oman Mountains) contain rugose corals. Praewentzelella regulare, a fasciculate coral, is found in clusters, with more than 80% of the colonies in growth position. The good preservation of microstructure and minimal taphonomic alteration (e.g., lack of postdepositional tilt or transport of colonies) allow to discuss whether or not live-live interactions for space, particularly intraspecific competition, has been preserved. The evaluation is based on the distribution of coral colonies mapped in the field, three-dimensional reconstruction of coral growth using serial cuts of a block and microfacies evaluation of thin sections. A rarely observed phenomenon of intraspecific competition is described herein and the term "intra-clonal aggression" is proposed for interactions between sedentary organisms of the same species leading to the distortion of skeletal elements of one colony.