Ostracods like ghosts in their shells: input of X-ray computed tomography for taxonomy and taphonomy of Early Triassic Hollinella

Abstract

Abundant ostracods of the genus Hollinella (Palaeocopida) have recently been described from the Early Triassic siliciclastic deposits of the paralic Mide B section, Yunnan Province, South China. These weathered and delicate specimens are preserved on the surface of cracked sediments, often still partly buried and impossible to extract. A small piece of siliciclastic sediments with Hollinella specimens visible on the surface has been investigated by X-ray computed tomography (CT) to search for better preserved and possibly complete specimens still enclosed in the matrix. While surface observations led to the attribution of these specimens to Hollinella panxiensis Wang already known from other Permian-Triassic sections in South China, this non-destructive technique reveals distinctive characters that drive us to introduce the new species Hollinella locula Forel nov. sp. Certain previous identifications of Hollinella panxiensis are re-attributed to Hollinella locula . The taphonomic analysis of this material is refined and confirms the previous interpretation of a low energy thanatocoenosis. This investigation further highlights the strong implications of new imaging techniques in diverse fields of ostracodology, even in the absence of soft parts preservation.