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

Martin Košťák,Adam Culka,Katarína Holcová,Dirk Fuchs,Natalia Hudáčková,Rastislav Milovský,Adam Tomašových,Juraj Šurka,Ján Schlögl,István Fözy,Martin Mazuch

doi:10.1038/s42003-021-01714-0

Abstract

A 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 assign Necroteuthis hungarica to the family Vampyroteuthidae that links Mesozoic loligosepiids with Recent Vampyroteuthis. Micropalaeontological, palaeoecological, and geochemical analyses demonstrate that Necroteuthis hungarica inhabited 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.

Highlights

A 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
Our goals are (1) to examine the gladius of N. hungarica using scanning electron microscope (SEM), μ-CT, geochemical analyses, and comparative anatomy, allowing us to properly assign this species, (2) to reconstruct the Oligocene environments inhabited by this cephalopod, and (3) and to track the onshore–offshore shift of vampyromorphs to bathyal and oxygen-depleted conditions since the Early Jurassic to Recent
The Oligocene Necroteuthis was a close relative of the extant deepsea vampire squid Vampyroteuthis

Summary

Introduction

A 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. Vampyroteuthis is characterized by a mosaic of characters of the superorders Decabrachia and Octobrachia (Octopodiformes or Vampyropoda in other terminologies), but morphological[15] molecular[16,17,18] and combined studies[19,20] indicate that Vampyroteuthis belongs to the octobrachian lineage It is unclear when species of the family Vampyroteuthidae evolved their unique adaptations as no Cenozoic species within the vampyromorph lineage were described until now. This gap indicates a major preservation bias (Lazarus effect), and inhibits any inferences about the timing of deep-sea colonization by vampire squids. The last stratigraphic record of loligosepiids corresponds to the Lower

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