New fossil constrictor snake from the canton of Zurich

by Dr. Torsten M. Scheyer, Paläontologisches Institut und Museum UZH

A new species of snake with the scientific name Palaeopython helveticus was recently described from 40-34 million year old Eocene karst columns in the Jurassic Lägern limestones near Dielsdorf, Canton Zurich.

fossil snake
Reconstruction of the Palaeopython helveticus sp. nov. and other fauna from the late Eocene of Dielsdorf.

During the middle to late Eocene, more than 34 million years ago, the climate was warm and humid in and around Zurich. During this period, there occurred karstification including crevasse and cave formation of the approximately 155 million years old Lägern limestones underground, while a rich fauna including primeval horses, crocodiles, small lemurs of the genus Necrolemur, as well as snakes lived in lush tropical forests and waters. Remains of all these animals are found in the Dielsdorf karst column infillings, with teeth, jaw remains and isolated bones of mammals, such as those of ungulates and small tree-dwelling lemurs, being particularly common. Snakes and lizards, however, are rather rare. Their fossils are mainly found in the form of isolated snake vertebrae and a lower jaw remnant of a relative of today's monitor lizards. Part of the previously described snake vertebrae and new fossil material were identified and assigned to a previously unknown type of non-toxic constrictor snake of the group "Booidea": the so-called Palaeopython helveticus. The group of the "Booidea" also includes the boa constrictor / common boa (Boa constrictor) and the anacondas from South America.

The vertebrae of Palaeopython helveticus had comparatively very high and arched neural arches, which end in high neural processes - they are thus well distinguishable from vertebrae of other species. High-resolution computed tomography images (micro-CT) were also used to gain insights into the interior of the bones. The micro-CT images of several vertebrae of different sizes show that external differences in the vertebral shape are due to ontogenetic variation, i.e., age-related differences within the new species Palaeopython helveticus instead of presenting features of different types of constrictor snakes.

team
Researchers Georgios L. Georgalis and Torsten M. Scheyer discussing the new snake fossil.

Palaeopython helveticus was published online on June 5th 2019 in the Swiss Journal of Geosciences:

Georgalis, G.L. and Scheyer, T.M. 2019. A new species of Palaeopython (Serpentes) and other extinct squamates from the Eocene of Dielsdorf (Zurich, Switzerland). Swiss Journal of Geosciences [doi: 10.1007/s00015-019-00341-6].