Bite marks and predation of fossil jawless fish during the rise of jawed vertebrates

Although modern vertebrate diversity is dominated by jawed vertebrates, early vertebrate assemblages were predominantly comprised of jawless fishes. Hypotheses for this faunal shift and the Devonian decline of jawless vertebrates include predation and competitive replacement. The nature and prevalence of ecological interactions between jawed and jawless vertebrates are highly relevant to both hypotheses, but direct evidence is limited. Here we use the occurrence and distribution of bite mark type traces in fossil jawless armoured heterostracans to infer predation interactions. A total of 41 predated specimens are recorded; their prevalence increases through time, reaching a maximum toward the end of the Devonian. The bite mark type traces significantly co-occur with jawed vertebrates and their distribution through time is correlated with jawed vertebrate diversity patterns, particularly placoderms and sarcopterygians. Environmental and ecological turnover in the Devonian, especially rel...