Fossil evidence for vampire squid inhabiting oxygen-depleted ocean zones since at least the Oligocene

Abstract

AbstractA marked 120 My gap in the fossil record of vampire squids separates the only extant species (Vampyroteuthis infernalis) from its Early Cretaceous, morphologically-similar ancestors. While the extant species possesses unique physiological adaptations to bathyal environments with low oxygen concentrations, Mesozoic vampyromorphs inhabited epicontinental shelves. However, the timing of their retreat towards bathyal and oxygen-depleted habitats is poorly documented. Here, we document a first record of a post-Mesozoic vampire squid from the Oligocene of the Central Paratethys represented by a vampyromorph gladius. We assignNecroteuthis hungaricato the family Vampyroteuthidae that links Mesozoic loligosepiids with RecentVampyroteuthis. Micropalaeontological, palaeoecological, and geochemical analyses demonstrate thatNecroteuthis hungaricainhabited bathyal environments with bottom-water anoxia and high primary productivity in salinity-stratified Central Paratethys basins. Vampire squids were thus adapted to bathyal, oxygen-depleted habitats at least since the Oligocene. We suggest that the Cretaceous and the early Cenozoic OMZs triggered their deep-sea specialization.