An enigmatic large discoidal fossil from the Pennsylvanian of County Clare, Ireland

Murray, John; MacGabhann, Breandán A.; Doyle, Eamon; Mángano, M. Gabriela; Tyrrell, Shane; Harper, David A.T.

Abstract

A rare and unusual large solitary discoidal fossil has been discovered on a paving slab quarried from the cyclothems of the Central Clare Group (Kinderscoutian, Pennsylvanian, Carboniferous), western Ireland. The fossil impression consists of a smooth raised inner discoidal area, surrounded by a slightly lower relief outer ring, ca. 130–135 mm in diameter, with eight prominent equidistant ovoid raised nodes towards the outermost margin. The octoradial body plan of this enigmatic specimen suggests a cnidarian connection and, as it is preserved as a positive hyporelief cast, it is tentatively interpreted as the resting trace of a large benthic anemone, which was either partially or fully infaunal. The discoidal fossil is interesting palaeoecologically; it occurs within the well-known Liscannor flagstone, which consists of thinly bedded, fine-grained sandstone that is extensively covered by prominent, sinuous to meandering, horizontal grazing trails attributed to Psammichnites plummeri. This sedimentary facies likely represents mouth-bar sedimentation on a delta front of a river-dominated delta. The discoidal impression occurs on a portion of the slab where these trace fossils are relatively scarce. Uncertainty surrounds the classification and interpretation of the disc due to its relatively simple morphological form, coupled with a lack of unequivocally diagnostic features — a problem commonly encountered in studies of discoidal fossils from both the Ediacaran and the Phanerozoic.

Citation

Murray, J., MacGabhann, B. A., Doyle, E., Mángano, M. G., Tyrrell, S., & Harper, D. A. (2023). An enigmatic large discoidal fossil from the Pennsylvanian of County Clare, Ireland. Palaeoworld, https://doi.org/10.1016/j.palwor.2023.01.008

• Journal Article Type: Article
• Acceptance Date: Jan 9, 2023
• Online Publication Date: Jan 16, 2023
• Publication Date: 2023
• Deposit Date: Jul 3, 2023
• Publicly Available Date: Jul 3, 2023
• Journal: Palaeoworld
• Print ISSN: 1871-174X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1016/j.palwor.2023.01.008