Jurassic Fossil Shows Pterosaurs Preyed on Soft-Bodied Cephalopods

Paleontologists in Germany have found the 150-million-year-old fossilized remains of the extremely rare squid Plesioteuthis subovata preserved with a tooth of a pterosaur species called Rhamphorhynchus muensteri.

Reconstruction of the hunting behavior 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. Image credit: Christian Klug / Beat Scheffold.

Reconstruction of the hunting behavior 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. Image credit: Christian Klug / Beat Scheffold.

Pterosaurs were Earth’s first flying vertebrates, with birds and bats making their appearances much later.

They lived at the same time as dinosaurs, between 210 million years ago (Triassic period) and 65 million years ago (Cretaceous period).

Some pterosaurs, such as the giant azhdarchids, were the largest flying animals of all time, with wingspans exceeding 9 m (30 feet) and standing heights comparable to modern giraffes.

What pterosaurs ate depended on where they lived: some species spent their lives around water, while others were more terrestrial.

Terrestrial pterosaurs hunted small dinosaurs, lizards, eggs, insects and various other animals. Aquatic pterosaurs ate a variety of marine life, including fish, mollusks, and crabs.

The long-tailed pterosaur Rhamphorhynchus muensteri was mainly a fish-eater. It lived in what is now Europe some 150 million years ago (the Jurassic period) and measured up to 1.3 m (4.3 feet) long with a wingspan of 1.8 m (5.9 feet).

Rhamphorhynchus muensteri apparently fed on aquatic animals by grabbing prey whilst flying directly above, or floating upon (less likely), the water surface,” said Ruhr-Universität Bochum paleontologist Rene Hoffmann and his colleagues.

The researchers came to this conclusion when they found a tooth of the aquatic pterosaur embedded in an exceptionally-preserved soft-tissue specimen of the cephalopod Plesioteuthis subovata.

“Examination under ultraviolet light reveals the pterosaur tooth is embedded in the now phosphatized cephalopod soft tissue, which makes a chance association highly improbable,” they said.

“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.”

Plesioteuthis subovata: (A) an adult specimen, 28.5 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) 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 Plesioteuthis subovata provides evidence of the gladius. Image credit: J. Härer.

Plesioteuthis subovata: (A) an adult specimen, 28.5 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) 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 Plesioteuthis subovata provides evidence of the gladius. Image credit: J. Härer.

The 150-million-year-old fossil of Plesioteuthis subovata was recovered from the Altmühltal Formation in the Solnhofen Archipelago, southeastern Germany.

The specimen has a total body length of 28.5 cm (11.2 inches), 18.8 cm (7.4 inches) of which comprises the mantle.

The embedded pterosaur tooth is approximately 1.9 cm (0.75 inches) long — only the crown is preserved — and 3 mm (0.12 inches) wide at its base. The tooth is slender and gently recurved, especially close to the pointed tip.

Much of the enamel near the tip of the tooth is covered by phosphatized mantle. However, the brown patches around the centre of the tooth may represent enamel.

Dr. Hoffmann and co-authors examined the specimen and concluded that the tooth of Rhamphorhynchus muensteri became associated with Plesioteuthis subovata through the pterosaur biting the squid.

“We present this association as the first direct evidence of a predator-prey interaction between pterosaurs and cephalopods,” they said.

“This interaction took place at or near the water surface. A scavenging feeding mode for Rhamphorhynchus muensteri 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 cephalopod carcass.”

“Most likely, the tooth broke off in the Plesioteuthis subovata 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 Plesioteuthis subovata 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 muensteri diet, this fossil provides evidence that Plesioteuthis subovata commonly lived in the upper part of the water column where it was accessible to pterosaurs.”

The findings were published in the journal Scientific Reports.

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R. Hoffmann et al. 2020. Pterosaurs ate soft-bodied cephalopods (Coleoidea). Sci Rep 10, 1230; doi: 10.1038/s41598-020-57731-2

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