Grenoble, June 23, 2022 – The Jurassic cephalopod Vampyronassa rhodanica, believed to be the earliest known ancestor of the modern-day vampire squid (Vampyroteuthis infernalis), was likely an active hunter – a lifestyle that contrasts with its opportunistic descendant. Scientists led by Sorbonne University came to this conclusion after analyzing microtomographic data from this rare fossil, acquired at the ESRF and the National Museum of Natural History in Paris. The results are published in Scientific Reports.
Vampyronassa rhodanica is believed to be one of the oldest relatives of the modern vampire squid (Vampyroteuthis infernalis), which is the only remaining living species of its family. This modern form lives in extremely deep ocean environments, often with little oxygen, and feeds on drifting organic matter. Like V. infernalis, the body of V. rhodanica was primarily made up of soft tissue. As this rarely fossilizes, little is known about the physical characteristics and evolutionary history of this family.
Despite the rarity of fossil material from this family, Alison Rowe of the Sorbonne University and her colleagues were able to study 3 well-preserved specimens of V. rhodanica from La Voulte-sur-Rhône (Ardèche, France), dating from more 164 million years ago. Eight-armed specimens were small, about 10 cm long, and had elongated, oval-shaped bodies with two small fins.
They took them to the ESRF for non-destructive 3D imaging: “We used synchrotron tomography at the ESRF to better identify the outlines of different anatomical features,” says Rowe. However, the task was difficult, as Vincent Fernández, scientist at the ESRF, explains: “The fossils are on small slabs, very difficult to scan. Additionally, soft tissue is preserved, but we needed phase contrast imaging to visualize the low density variation in the data. The coherence of the ESRF ID19 beamline was therefore very important to perform propagation phase contrast computed tomography and follow all the smallest details, such as suckers and small fleshy extensions, called cirri”.
Imaging revealed previously unknown details regarding the cupping and crown of the arm. Comparison with tomographic data from an existing specimen of V. infernalis digitized at the American Museum of Natural History in New York allowed the team to determine that the suckers and cirri of V. rhodanica were proportionally more robust than those of V. infernalis. The researchers also noticed that the configuration of the suckers and cirri on the longest pair of dorsal arms was different from that on the rest of the arms. “We believe that the morphology and placement of V. rhodanica suckers and cirri in the differentiated crown of arm allowed V. rhodanica to have increased aspirational and sensory potential compared to the modern form, and made them helped them manipulate and hold their prey,” says Rowe.
The presence of muscular suckers on each of the arms and conical sensory appendages to detect prey suggests that V. rhodanica was likely an active predatory hunter. This contrasts with its more opportunistic descendant, the vampire squid, which has adapted to a low-energy, deep-ocean lifestyle.
Alison J. Rowe, Isabelle Kruta, Neil H. Landman, Loïc Villier, Vincent Fernandez, Isabelle Rouget, Exceptional Soft Tissue Preservation of Jurassic Vampyronassa rhodanica Provides New Insights into Vampyroteuthid Evolution and Paleoecology, Scientific Reports, 23 June 2022. https://www.nature.com/articles/s41598-022-12269-3
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