Vampyronassa

Credit: A. Lethiers.

*Vampyronassa* is an extinct genus of vampire squid that lived in France during the Middle Jurassic.

## History

*V. rhodanica* is known and named after La Voulte-sur-Rhône in Ardèche, France. From here, there are about 20 specimens but only 8 have been described as of 2022. These specimens are important to cephalopod phylogenies because they preserve an astounding amount of 3D detail that allows for close study with the arrival of modern technology. In 2022, they were reexamined, being the first internal and external analysis of the genus using detailed reconstruction with arm crown morphology especially considered, MNHN.F.74247 is the holotype, being a complete individual with 3D soft tissue preserved. MNHN.F.74243 is a paratype.

## Description

*Vampyronassa* differs from modern vampire squids, having longer first dorsal arm, an elongated hyponome and mantle. Fischer and Riou detect luminous organs that were not confirmed in Rowe et al. (2022)'s analysis, instead finding two semi-ovoid structures within the peripheral mantle tissue in the posterior-most area of the body in MNHN.F.74244. These are dense and are in a similar position, although being 4-5x larger in MNHN.F.74244. They are only seen in tomography, do not appear in the other two specimens sampled and appear to be displaced fin cartilage. The head-mantle fusion is evident, with the head being about half as wide as the mantle length. The mantle tissue extends from the margins in MNHN.F.74247 and 74244. This is not splayed in preservation in 74243. The eyes are preserved well, although their position is relative given the amount of of distortion before mineralization. They are subcircular, have undergone various compaction and have a diameter of 5-7 millimeters. They arm crowns are well preserved and are spread across 8 arms with distinct axial nerves. The dorsal pair is equivalent to the length of the mantle and ~2x as long as the sessile arms.

## Classification

Before 2022, the affinities of *Vampyronassa* were doubted, with Rowe et al. using Synchrotron X-ray microtomography to clearly examine the structures present. They determined that the unique form of sucker attachment indicates ancestry to the living vampire squid, although it is present in other Jurassic taxa. This taxon is unique for soft tissue preservation, as such is relatively unknown for other genera and hinders research.

## Paleobiology

Despite being ancestral to the vampire squid, an opportunistic detritivore of zooplanktivore, *Vampyronassa* is suggested to be a pelagic predator. This contrast is typical of the hypothesis that these forms diversified on continental shelves before they further adapted to the deep sea as seen today in the Oligocene.

## Paleoecology

About 20 specimens have been collected and assigned by Fischer and Riou from the Lagerstätten of La Voulte-sur-Rhône, dating to the Callovian of the Middle Jurassic and representing a bathyal ecosystem that is offshore with steep, fault-controlled bathymetric gradients. This makes the site unique for 3D preservation of photic and aphotic taxa. Most of the fauna is represented by arthropods, with several echidoderms, bivalves, brachiopods and fish. Cephalopods like *Vampyronassa* contribute 10% of the diversity.

## References

* https://en.wikipedia.org/wiki/Vampyronassa
* https://www.nature.com/articles/s41598-022-12269-3#Sec2