First record of malformed trilobites from the Silurian of Ukraine

This article presents the first documented case of malformed trilobite exoskeletons from the Silurian of Ukraine. Fossils of animals with injuries and pathologies are of significant palaeobiological value, as they provide essential insights into the evolution of predator-prey interactions, trophic networks, animal behavior, and genetic anomalies. The material under study consists of two pygidia of Bumastus restevensis from the Rykhta Formation (Ludlow, Upper Silurian) in Khmelnytskyi Oblast (western Ukraine, the Volyn-Podillia Monocline). A comparative analysis of these malformed exoskeletons with similar specimens from other global localities reveals that they are unique, with no direct analogues. The injuries observed are interpreted as “predation scars,” indicative of unsuccessful predatory attacks. The distinctive morphology of these malformations suggests that they were most likely inflicted by cephalopods, arthropods, such as phyllocarid crustaceans and/or aquatic chelicerates, or fishes.