Perils of the Paleocene: vertebrate and invertebrate induced bioerosion in freshwater turtles from Tiupampa, Bolivia (early Paleocene)

Abstract

Abstract Turtles provide an important link between terrestrial and aquatic ecosystems, acting as both predators and prey, while also being an important host for a range of parasites. The dermal armor that characterizes the group ensures their abundance in the vertebrate fossil record and preserves evidence of biotic interactions. We evaluated the ichnofauna and body size distributions of turtles from the early Paleocene Tiupampa Fauna (Santa Lucía Formation), Bolivia, to reconstruct aspects of the Tiupampan ecosystem. We observed bite traces in several specimens of Lapparentemys vilavilensis from the ichnogenera Brutalichnus , Linichnus , Machichnus , and Nihilichnus , which are consistent with predation or scavenging by crocodyliforms, including sebecids and possibly dyrosaurids. The carapaces and plastra also include evidence of invertebrate activity ( Karethraichnus and cf. Thatchtelithichnus ), interpreted to represent parasitism, possibly by leeches or trematodes. Evidence of fungal or bacterial infection, through records of ichnogenera such as Gunnellichnus or Violinichnus , is rare, but may suggest host–parasite specialization was present shortly after the Cretaceous–Paleogene boundary. The rarity of these features and the general stability of the population, assessed through body size distributions, possibly suggests that the turtles of Tiupampa were not experiencing particularly high levels of environmental stress.