Evidence for the Cretaceous shark Cretoxyrhina mantelli feeding on the pterosaur Pteranodon from the Niobrara Formation

Abstract

A cervical vertebra of the large, pelagic pterodactyloid pterosaur Pteranodon sp. from the Late Cretaceous Niobrara Formation of Kansas, USA is significant for its association with a tooth from the large lamniform shark, Cretoxyrhina mantelli. Though the tooth does not pierce the vertebral periosteum, the intimate association of the fossils-in which the tooth is wedged below the left prezygapophysis-suggests their preservation together was not mere chance, and the specimen is evidence of Cretoxyrhina biting Pteranodon. It is not possible to infer whether the bite reflects predatory or scavenging behaviour from the preserved material. There are several records of Pteranodon having been consumed by other fish, including other sharks (specifically, the anacoracid Squalicorax kaupi), and multiple records of Cretoxyrhina biting other vertebrates of the Western Interior Seaway, but until now interactions between Cretoxyrhina and Pteranodon have remained elusive. The specimen increases the known interactions between large, pelagic, vertebrate carnivores of the Western Interior Seaway of North America during the Late Cretaceous, in addition to bolstering the relatively small fossil record representing pterosaurian interactions with other species.

Keywords: Behaviour; Carnivore-consumed; Palaeoecology; Predation; Pterosaur; Scavenging.

Figure 1. Mounted Pteranodon and close up of the neck.

(A) mounted Pteranodon sp. skeleton LACM 50926 on display in the Los Angeles county museum with highlighted section of the vertebrae shown below; (B) Close up of the vertebral series and shark tooth (indicated by an arrow). Cervical vertebrae III–VII are indicated. Scale bar is 50 mm—this is an approximate value based on published measurements of the vertebrae. Image credit: (A) Stephanie Abramowicz, courtesy Dinosaur Institute, Natural History Museum of Los Angeles County, (B) David Hone.

Figure 2. Two close up views of the Cretoxyrhina mantelli tooth with tracings.

(A) left dorsolateral view; (B) left dorsoventral view showing its intimate association with cervical vertebra IV. The tooth is highlighted in medium grey, the 4th cervical vertebra in pale grey and the 5th cervical in dark grey. Abbreviations: ns neural spine, prz prezygopophysis, psz postzygopophysis, st shark tooth. Image credit: David Hone.

Figure 3. Cretoxyrhina mantelli anterior teeth.

Tracing of Cretoxyrhina mantelli anterior teeth from Bourdon & Everhart (2011), their figure 5, mirrored from their original). (A) position 3 in the jaw; (B) position 4; (C) LACM 50926 tooth. The bases of the teeth are shaded in pale grey and the enamel is dark grey. Image credit: David Hone.

Figure 4. Restored scene of Cretoxyrhina attacking Pteranodon.

Life reconstruction of a c. 2.5 m long breaching Cretoxyrhina mantelli biting the neck of a 5 m wingspan Pteranodon longiceps, a scene inspired by LACM 50926. The predatory behaviour of this scene is speculative with respect to the data offered by the specimen, but reflects the fact that Cretoxyrhina is generally considered a predatory species, the vast weight advantage of the shark against the pterosaur (see text), and the juvenile impulse of the artist to draw an explosive predatory scene. Image credit: Mark Witton.