Tanystropheus ‘decapitation’ in the Triassic

Spielman and Mujal 2023 reported bite marks
at the base and in the middle of the cervical series in two specimens of Tanystropheus preserving no post-cervical bones.

In the large reptile tree (LRT, 2276 taxa) Tanystropheus and its relatives (Fig 3 from 2011) are lepidosaurs, not archosauromorphs. We’ve known this since Peters 2007. Spielman and Mujal are following out-of-date university textbooks.

Wild 1973 counted only 12 cervicals.

Further study of Wild 1973 reveals Tanysitrachelia (Peyer 1931) was a lepidosaur clade that included Tanystropheus and Prolacerta. That clade was accepted by Kuhn 1946. This is one source of the Prolacertiformes controversy, which the LRT resolved a decade ago by adding pertinent taxa (Peters 2007). Prolacerta is an archosauromorph. Tanystropheus is a lepidosauromorph. This split goes back to the Viséan. This hypothesis of interrelationships currently needs confirmation, refutation or modification, so please build your own LRT and tell us your results.

Unique? No. Dinocephalosaurus (Fig 3) evolved a similar neck by convergences. So did azhdarchid pterosaurs. So did flamingos. Cranes. Storks. Giraffes. No reason to mention little Langobardisaurus (Fig 3) because it is too closely related to Tanystropheus.

The authors report,
“Here, we show that the neck was completely severed in two Tanystropheus specimens (Fig 1), most likely due to a predatory attack, providing vivid evidence of predator–prey interactions among Mesozoic marine reptiles that are rarely preserved in the fossil record. The recurring incidence of decapitation suggests that the elongate neck was a functional weak spot in Tanystropheus, and possibly the long-necked marine reptile bauplan more generally.”

As illustrated above, Wild 1973 (Fig 2) presented several other Tanystropheus specimens that did not show the pattern of decapitation described by Spielman and Mujal. So: no ‘functional weak spot.’ Cherry-picking two specimens only increased the editiorial and publicity value (Fig 5) of the Spielman and Mujal headline. Not sure if Wild

Tanystropheus longobardicus
(Tanystropheus conspicuus von Meyer 1855, Tribelesodon longobardicus Bassani 1886, Tanystropheus longobardicus Peyer 1930) Anisian, Middle Triassic, ~240 mya, ~4.5m in length, was considered a pterosaur before Peyer (1930) established that the long bones were neck bones, not wing bones. Derived from a sister to the the T4822 specimen of Macrocnemus, Tanystropheus was a sister to the much smaller Tanytrachelos and Langobardisaurus, rather than the convergent Dinocephalosaurus.

(T/2793 Exemplar C. T/2917 Exemplar K. T/2819 Exemplar Q of Wild 1973, Fig 2) was not a terrestrial predator, but a bipedal, vertically oriented, aquatic, sit-and-wait ambusher. One can imagine Tanystropheus sitting on the sea floor, emitting a bubble net from its long tracheal reservoir of dead air, rising from below to concentrate squid and fish into a small ball near the surface. Transporting a swallow of air to the lungs would have involved upending the entire body at least a little lower than horizontal, given water vs air pressures.

References
Kuhn O 1946. Das System der fossilen und rezenten Amphibien und Reptilien [The system of fossil and recent amphibians and reptiles]. Bericht der Naturforschenden Gesellschaft in Bamberg 29:49-67
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peyer B 1931. The Triassic fauna of the Tessiner Chalk Alps. Abhandlugen der Schweizerischen Palaeontolgishen Gesellschaft 51.
Spiekman SNF and Mujal E 2023. Decapitation in the long-necked Triassic marine reptile Tanystropheus. Current Biology. www.cell.com
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-162 plus plates.

wiki/Tanystropheus
Tanysitrachelia – Mindat.org