Exceptional soft-tissue preservation of Jurassic Vampyronassa rhodanica provides new insights on the evolution and palaeoecology of vampyroteuthids

Abstract

Although soft tissues of coleoid cephalopods record key evolutionary adaptations, they are rarely preserved in the fossil record. This prevents meaningful comparative analyses between extant and fossil forms, as well as the development of a relative timescale for morphological innovations. However, unique 3-D soft tissue preservation of Vampyronassa rhodanica (Vampyromorpha) from the Jurassic Lagerstätte of La Voulte-sur-Rhône (Ardèche, France) provides unparalleled opportunities for the observation of these tissues in the oldest likely relative of extant Vampyroteuthis infernalis. Synchrotron X-ray microtomography and reconstruction of V. rhodanica allowed, for the first time, a high-resolution re-examination of external and internal morphology, and comparison with other fossil and extant species, including V. infernalis. The new data obtained demonstrate that some key V. infernalis characters, such as its unique type of sucker attachment, were already present in Jurassic taxa. Nonetheless, compared with the extant form, which is considered to be an opportunistic detritivore and zooplanktivore, many characters in V. rhodanica indicate a pelagic predatory lifestyle. The contrast in trophic niches between the two taxa is consistent with the hypothesis that these forms diversified in continental shelf environments prior to the appearance of adaptations in the Oligocene leading to their modern deep-sea mode of life.