An extraordinary long neck

The neck of Tanystropheus – an extinct reptile from the Triassic – is more than twice as long as the animal’s body. Not only is the neck length unusual, but also the small number of only 13 cervical vertebrae (for comparison: the neck of a swan consists of 26 cervical vertebrae). The neck of Tanystropheus is therefore the result of the extreme elongation of the individual cervical vertebrae. No other animal that has ever lived on Earth has developed such long vertebrae.

The exceptional anatomy of Tanystropheus raises a lot of questions and most of them have not yet been fully solved. Concerning the function of the neck, it is assumed that the cervical vertebral column was slender and not very mobile. It was probably used to catch prey by ambush. In a recent study (Rytel et al. 2024 R Soc Open Sci), Prof. Dr. Christine Böhmer and her colleagues from the Polish Academy of Sciences and the University of Warsaw (Poland) as well as the Museum of Natural History in Stuttgart took a closer look at the evolution of the neck in Tanystropheus und relatives.

First, more than 100 cervical vertebrae of the extinct reptiles were screened and photographed. Subsequently, state-of-the-art morphometric methods were used to quantify and compare the shape of the fossil bones. The statistical analyses of the data showed that the long neck of Tanystropheus evolved through a combination of two processes. On the on hand, some thoracic vertebrae acquired cervical vertebral morphology (i.e., “cervicalization”) and were thus integrated into the neck. On the other hand, the cervical vertebrae in the anterior part of the neck (near the cranium) got particularly elongated. This mechanism of neck elongation in Tanystropheus differs from the mechanism in other relatives such as birds. The neck elongation in birds was achieved by elongation of the middle part of the neck.

Reference:

Rytel A, Böhmer C, Spiekman SNF and Talanda M (2024) Extreme neck elongation evolved despite strong developmental constraints in bizarre Triassic reptiles – implications for neck modularity in archosaurs. Royal Society Open Science 11: 240233. DOI: https://doi.org/10.1098/rsos.240233.