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| Reconstruction of the hunting behaviour of Rhamphorhynchus muensteri, flying close to the water surface to grab soft-bodied cephalopods such as Plesioteuthis subovata that lived in the uppermost part of the water column. in Hoffmann, Bestwick, Berndt, et al., 2020.
Artwork by C. Klug and B. Scheffold.
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Abstract
Direct evidence of successful or failed predation is rare in the fossil record but essential for reconstructing extinct food webs. Here, we report the first evidence of a failed predation attempt by a pterosaur on a soft-bodied coleoid cephalopod. A perfectly preserved, fully grown soft-tissue specimen of the octobrachian coleoid Plesioteuthis subovata is associated with a tooth of the pterosaur Rhamphorhynchus muensteri from the Late Jurassic Solnhofen Archipelago. Examination under ultraviolet light reveals the pterosaur tooth is embedded in the now phosphatised cephalopod soft tissue, which makes a chance association highly improbable. According to its morphology, the tooth likely originates from the anterior to middle region of the upper or lower jaw of a large, osteologically mature individual. We propose the tooth became associated with the coleoid when the pterosaur attacked Plesioteuthis at or near the water surface. Thus, Rhamphorhynchus apparently fed on aquatic animals by grabbing prey whilst flying directly above, or floating upon (less likely), the water surface. It remains unclear whether the Plesioteuthis died from the pterosaur attack or survived for some time with the broken tooth lodged in its mantle. Sinking into oxygen depleted waters explains the exceptional soft tissue preservation.
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| Figure 1: Plesioteuthis subovata from the Late Jurassic Solnhofen Archipelago. An adult specimen, 28 cm long, preserved with ink sac and duct, arm-head complex, well-preserved mantle musculatures (transverse striation) and a pterosaur tooth. (B) Close-up of the 19 mm long, slightly curved Rhamphorhynchus muensteri tooth crown under normal light. (C) Ultraviolet (UV) light reveals that the tooth apex is partially covered with now phosphatized mantle tissue. (D) Posterior part of the specimen with faint imprints probably representing a terminal fin, but UV light provides no evidence of fin musculature (E). The posterior mantle margin is incomplete and a straight structure with a double keel typical for P. subovata provides evidence of the gladius.
All photographs by J. Härer.
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| Figure 2: Cephalopod gladius and pterosaur skull reconstructions. (A) Plesioteuthis prisca with an unipartite median keel. (B) Plesioteuthis subovata with a bipartite median keel. (C) Rhamphorhynchus skull with upper and lower jaw dentition (black arrows indicate potential position of the broken off tooth that became stuck in the Plesioteuthis mantle tissue).
Skull drawing after Bennett, 1995.
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| Figure 3: Reconstruction of the hunting behaviour of Rhamphorhynchus muensteri, flying close to the water surface to grab soft-bodied cephalopods such as Plesioteuthis subovata that lived in the uppermost part of the water column. Artwork and background photograph by C. Klug and B. Scheffold using a model produced by B. Scheffold (Zürich). |
Conclusion:
We describe an adult specimen of the extremely rare octobrachian coleoid cephalopod Plesioteuthis subovata preserved with a tooth of the pterosaur Rhamphorhynchus muensteri in its mantle tissue. We present this association as the first direct evidence of a predator-prey interaction between pterosaurs and cephalopods. This interaction took place at or near the water surface. A scavenging feeding mode for Rhamphorhynchus is doubtful because the pterosaur is unlikely to have dived to the highly dangerous anoxic sediment floor to access carrion. It is also unlikely that tooth breakage would occur while consuming the soft decaying mantle of a coleoid carcass. Most likely, the tooth broke off in the Plesioteuthis mantle when the pterosaur attacked and the cephalopod tried to escape. High mechanical stress was exerted to the base of the teeth that were in direct contact with the cephalopod. This fractured at least one tooth, which remained stuck in the mantle. It is impossible to assess whether the Plesioteuthis died as a result of the pterosaur attack or survived with the broken tooth in its mantle. In addition to revealing cephalopods as a likely part of the Rhamphorhynchus diet, this fossil provides evidence that Plesioteuthis commonly lived in the upper part of the water column where it was accessible to pterosaurs.
R. Hoffmann, J. Bestwick, G. Berndt, R. Berndt, D. Fuchs and C. Klug. 2020. Pterosaurs ate Soft-bodied Cephalopods (Coleoidea). Scientific Reports. 10, 1230. DOI: 10.1038/s41598-020-57731-2
