Abstract

Detailed analysis of certain growth characteristics in Trabeculites maculatus contributes to an understanding of the paleobiology and phylogeny of early tabulate corals. Some coralla of T. maculatus contain peculiar, vertically oriented cylindrical lacunae (open areas) that are lenticular, or in one case circular, in cross section. The nature of these structures and their relation to adjacent corallites suggest that they were formed by the coral in response to soft-bodied biotic associates of unknown taxonomic affinity.

Trabeculites maculatus is an unusual tabulate coral featuring both axial and lateral modes of corallite increase. Axial increase was common, often occurring in association with rejuvenation following injury and less commonly involving normal, undamaged corallites. Lateral increase of normal corallites was typical, but this form of increase could also be involved in the termination of lacunae and occurred in response to a divergent growth pattern around the circular lacuna. Corallite decrease was fairly common, usually taking place adjacent to lenticular lacunae but in some cases involving normal corallites not associated with lacunae. Corallite fusion was uncommon; it could be either temporary or permanent. Conspicuous relocation of corallites and restructuring of corallite arrangement generally involved mass rejuvenation and/or regeneration, usually over a large surface area of the corallum.

The growth features in T. maculatus are fundamentally the same as those in the co-occurring Saffordophyllum newcombae, including types of axial increase unknown in other tabulate corals. The basic paleobiologic similarity of these species supports the interpretation that the genera they represent are closely related phylogenetically. The relationship of these taxa to other tabulates, however, remains unresolved.

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