Article: A Silurian ophiuroid with soft-tissue preservation

Most Palaeozoic brittle stars lack the fused arm ossicles (vertebrae) that facilitate the remarkable mode of walking that characterizes living forms. Here we describe a stem ophiuroid from the Herefordshire Lagerstätte (Silurian, Wenlock Series), which is exceptional in preserving the body cavity uncompacted and the long tube feet. We assign the specimen to the order Oegophiurida. The morphology of the arms and attitude of the specimen suggest that locomotion may have been achieved by arm propulsion combined with podial walking. This ophiuroid increases the diversity of echinoderm higher taxa with preserved soft parts represented in the Herefordshire Lagerstätte.

We thank Carolyn Lewis for technical support and David Edwards and the late Roy Fenn for general assistance. Our research was funded by the Natural Environment Research Council (grant NE/F018037/1), the Leverhulme Trust (grant EM-2014-068), the Yale Peabody Museum of Natural History Invertebrate Palaeontology Division, and Natural England. RPC was supported by the Palaeontological Association through its Undergraduate Research Bursary scheme (grant PA-UB201905). We are grateful for comments from Fred Hotchkiss and an anonymous reviewer, which resulted in important improvements to the paper.

DeJS, DaJS, DEGB and MDS conceived the study; MDS and DeJS curated the data; DeJS, DaJS, DEGB, MDS and RPC acquired the funding; RPC, MDS, DEGB, IAR, DaJS and DeJS carried out the investigation; MDS, DeJS and DaJS devised the methodology; DeJS carried out the project administration; MDS implemented the software; MDS and IAR supervised RPC; RPC, MDS and DEGB created Figure 1; RPC, MDS and DEGB prepared the first draft of the paper; and DEGB, MDS, IAR, DeJS, DaJS and RPC reviewed and edited the paper.