Mazon Creek Bromalites Evidence a Specialized, Xiphosurid-Rich Diet for Pennsylvanian Predators

The Mazon Creek Konservat-Lagerstätte is a globally significant Pennsylvanian (late Carboniferous) fossil assemblage characterized by exceptional soft-tissue preservation in siderite concretions. Coprolites documented from this site have provided crucial insights into trophic interactions within a Pennsylvanian deltaic environment but have not been widely studied. To expand the limited record in the literature of Mazon Creek bromalites, we investigate four shelly specimens, considered regurgitalites, with high concentrations of fragmented xiphosurid (Euproops danae) exoskeletal elements, indicating a specialized, durophagous diet. The sizes of prosomal and thoracetronic fragments within regurgitalites reveal a constrained prey size range, suggesting either prey size selection by the predator or differential survival of larger individuals. These findings highlight successful predation on xiphosurids within the late Carboniferous and provide direct evidence of their position within benthic food webs. This study underscores the utility of bromalites in informing paleoecological reconstructions and contributes to a broader understanding of trophic structures within late Carboniferous deltaic ecosystems.