T218 Advances in Arthropod Paleobiology I: Honoring the Illustrious Career of Rodney Feldmann

Wednesday, 18 October 2023
8:00 AM - 12:00 PM
304 / 305

OSTRACODS PRESERVED WITHIN CEPHALOPOD CONCHS FROM THE CARBONIFEROUS OF UK: THE RECORD OF CRYPTIC MOULTING BEHAVIOUR

Paper number: T218-11
Program: Technical Sessions
Time: 10:25 AM – 10:40 AM

Authors

Abstract

Monospecific accumulations of two species of ostracods, a spine-bearing Janischewskya? sp. and a smooth-shelled Cavellina? sp., were found preserved within the deeper parts of the body chamber, siphuncle and camerae of two goniatites and one nautiloid specimen, all from the Mississippian (Asbian) Cracoean reefs of North Yorkshire, UK. The ostracod concentrations occur as well-preserved single valves of juvenile individuals, with delicate spines of Janischewskya? sp. intact on most specimens. The ostracod valves are not associated with other fossils, bioclasts or sediment grains, and rarely occur in the surrounding matrix outside the shells. This indicates that the concentrations of ostracods did not result from a sedimentary process. The occurrence of these ostracods in the deeper parts of the conchs, the absence of associated adult individuals, and the lack of morphological features indicative of scavengers, all negate any hypothesis that the ostracods represent mass mortality events following feeding and subsequent burial by obrution. Instead, their preservation suggests that the ostracods deliberately entered the empty conchs in order to moult in a sheltered environment. In the case of the smooth-shelled Cavellina? sp., the ostracod valves preserved within a camera of the nautiloid have similar size, indicating that a synchronized mass moulting may have taken place with this species.These accumulations thus represent the first examples of cryptic moulting in ostracods. They also imply that such behaviour in this group of arthropods has a long evolutionary history, at least since the Carboniferous, and potentially may still be persistent in present day ostracods.

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

doi: 10.1130/abs/2023AM-390880

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.