T44 New Voices in Geobiology (Posters)

Sunday, 15 October 2023
8:00 AM - 5:30 PM
Hall B

LUBLINOPHYLLUM FLACCIDUM CORAL PATCHREEFS FROM THE BANGOR LIMESTONE (SERPUKHOVIAN) SHOW PHENOLOGY PATTERNS AND EVIDENCE OF EXTERNAL BROODING WHICH COULD BE USED AS PALEOCLIMATE PROXY DATA

Paper number: T44-8
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Paleozoic colonial rugose corals are an underutilized proxy data source for paleoclimatic changes. In North America, samples of the fasciculate rugose coral, Lublinophyllum flaccidum (Easton, 1943) from patch reefs in the Bangor Limestone (Serpukhovian) of Franklin County, Alabama, were collected and data from ~200 serially thin sectioned specimens used to revise the description of L. flaccidum, to include its early ontogeny, the phenology of cardinal septa shortening and septa dilation, and intraspecies variation. Many of the L. flaccidum samples had ~6-10 corallite juveniles aligned along the outer margins, a process described as parricidal, or lateral increase. Literature review of this mode of reproduction suggests the increase seen in L. flaccidum may be evidence of exterior brooding reproduction as seen in many taxa of Actinaria, including the sea anemone Epiactis prolifera (Verril, 1869). With the exterior type of brooding exhibited by E. prolifera, offspring remain in contact with the adult’s ectoderm until dispersal; the ectoderm (outer epithelium) of Rugosa corals is often compared to the same layer on polyps of Scleractinia corals where growth is modified by the development of calcioblast cells for exoskeleton production. Brooding would allow the following biological and environmental conclusions that could be used as proxy data in future paleoclimate studies: 1) the colony experienced a continuous reproduction strategy instead of seasonal, due to the presence of different sized juveniles; 2) presence of multiple nearby juveniles, almost to the point of overcrowding, could be due to the dispersal cost of the larger and slowly moving brooded juveniles vs. egg and larva dispersal; 3) extant brooding species reproduce in some climates and not in others, for example, L. federowski (Khoa, 1977) and L. thailandicum (Fontaine, 1982), and some L. flaccidum from other localities do not exhibit brooding: 4) the percentage of brooding adults of E. prolifera, could be inversely related to sea water temperature, and L. flaccidum could have a similar relationship.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-394946

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