Multispecies shark feeding in the Trans-Saharan Seaway: evidence from Late Cretaceous dyrosaurid (Crocodyliformes) fossils from northeastern Mali

Abstract

Feeding traces help to characterize trophic interactions of ancient ecosystems. In rare cases, they may also provide information that is not otherwise represented by body fossils in a particular paleoenvironment. Here, we describe a diverse suite of surficial bone modifications preserved on dyrosaurid crocodyliform bones. These new fossils come from extensive Upper Cretaceous (Maastrichtian) bone and coprolite-dominated phosphate conglomerates from deposits of the Trans-Saharan Seaway in northern Mali. Five specimens have bite traces indicative of feeding by at least two species of neoselachian sharks. Features of some traces suggest they were not made in a fatal attack, but after the dyrosaurids had died, and therefore represent instances of scavenging. Other traces may be attributed to predation or early scavenging. In addition to the shark bite traces, one specimen bears minute, crescent-shaped traces that we tentatively attribute to invertebrate activity. Importantly, the traces described here document the presence of species for which body fossils have not yet been discovered