Malformed trilobites have been documented in deposits ranging from the Cambrian to the Permian. Continued examination of novel malformed specimens provides insight into how trilobites recovered from injuries, experienced genetic abnormalities, and adapted to pathological conditions. This study focuses on trilobites from the Silurian and Devonian of Europe, presenting new records of: (i) a moulting-related injury in Lioharpes venulosus; (ii) genetic malformations in Calymene blumenbachii and Treveropyge sp.; and (iii) a moulting injury or genetic anomaly in Scutellum (Scutellum) pardalios. Additionally, we record evidence of bryozoan growth on a C. blumenbachii specimen. Our findings provide important data for contextualizing the paleobiology of early and middle Paleozoic trilobites, especially related to responses to ecological pressures.

Key words: Trilobita, Calymene, Treveropyge, Lioharpes, Scutellum , evolution, injuries, malformations, teratologies.

Russell D.C. Bicknell [rdcbicknell@gmail.com, rbicknell@amnh.org; ORCID: https://orcid.org/0000-0001-8541-9035], Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY, 10024, USA and Palaeoscience Research Centre, School of Environmental & Rural Science, University of New England, Armidale, NSW 2351, Australia. Patrick M. Smith [patrick.smith@australian.museum; ORCID: http://orcid.org/0000-0002-4359-8001], Palaeontology Department, Australian Museum Research Institute, Sydney, New South Wales, Australia and Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia. Lisa Amati [lisa.amati@nysed.gov; ORCID: https://orcid.org/0000-0001-9766-7036], Paleontology, New York State Museum, 222 Madison Avenue, Albany, NY 12230, USA. Melanie J. Hopkins [mhopkins@amnh.org; ORCID: https://orcid.org/0000-0002-3580-2172], Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY, 10024, USA.