Georgalis G. L., Zaher H. & Laurin M. 2025. — Introduction to: Snakes from the Cenozoic of Europe – towards a macroevolutionary and palaeobiogeographic synthesis, in ­Georgalis G. L., Zaher H. & Laurin M. (eds), Snakes from the Cenozoic of Europe – towards a macroevolutionary and palaeobiogeographic synthesis. Comptes Rendus Palevol 24 (3): 45-49. https://doi.org/10.5852/cr-palevol2025v24a3

Snakes have long been important components of most European ecosystems. This is not readily obvious to herpetologists given that the modest extant taxonomic richness represents simply a glimpse of their astonishing abundance in Europe during much of the Cenozoic. Indeed, the fossil record documents a high taxonomic diversity of snakes, which included a plethora of distinct shapes, sizes, feeding and reproductive adaptations, ecological strategies, and locomotion (Rage 1984; Ivanov 2022; Smith & Georgalis 2022). Interestingly (as of February 2025), as many as 162 extinct species have been established from the Cenozoic of Europe; these 162 species have been assigned to 92 different genera, among which 56 genera are extinct and established upon European fossil material, 10 genera are extinct and have originally established upon fossil material from other continents, and 26 represent extant genera (GLG, unpublished data). This high diversity included both early representatives of extant clades that now inhabit the continent, such as erycids, colubrids, natricids, and viperids (Szyndlar 1984, 1991a, b; Ivanov 2022), giant forms of extant clades of the continent (Georgalis et al. 2016), as well as taxa that are now absent from Europe, such as pythonids and elapids (Rage 1984; Szyndlar 1991a, b; Szyndlar & Rage 2003; Zaher & Smith 2020; Ivanov 2022), but also a parade of unique, bizarre, and now extinct clades, such as palaeophiids, russellophiids, and anomalophiids (Rage 1983, 1984; Georgalis et al. 2020; Smith & Georgalis 2022; Fig. 1).

Fossil snake remains from the European Cenozoic consist primarily of isolated vertebrae (Rage 1984; Szyndlar 1984, 1991a, b; Venczel 2000; Szyndlar & Rage 2003; Ivanov 2022; Smith & Georgalis 2022; Fig. 1). Articulated vertebrae and cranial remains are less common (e.g. Owen 1850; Szunyoghy 1932; Hoffstetter 1939; Szyndlar 1984; Ivanov 1999; Venczel 2000; Szyndlar & Rage 2003; Georgalis et al. 2021; Georgalis & Scheyer 2022; Čerňanský 2024; Fig. 1), while complete skeletons are exceptionally rare and typically limited to a few Fossillagerstätte localities (Meyer 1845; Massalongo 1859; Janensch 1906; Kuhn 1939; Szyndlar 1992; Szyndlar & Böhme 1996; Baszio 2004; Smith & Scanferla 2016, 2021, 2022; Scanferla & Smith 2020; Zaher & Smith 2020; Georgalis et al. 2021; Seghetti et al. 2022; Palci et al. 2024; Fig. 1). Remarkably, even mummified portions of snake bodies have been recovered in exceptional cases (Filhol 1877; Rochebrune 1884; Georgalis et al. 2021; Fig. 1)! Notably, the beautifully preserved skeletons from the Fossillagerstätte localities of Messel and Geiseltal in Germany have provided and continue to provide critical insight into the cranial anatomy and intracolumnar variation of multiple extinct snake taxa (Kuhn 1939; Baszio 2004; Scanferla & Smith 2020; Zaher & Smith 2020; Smith & Scanferla 2021, 2022; Georgalis et al. 2021; Palci et al. 2024; Fig. 1). Additionally, these fossils offer valuable information on palaeoecology and trophic interactions (e.g. Smith & Scanferla 2016).

The European Cenozoic fossil record of snakes dates back to the Paleocene and encompasses a wide geographic distribution. As such, it provides valuable insights into major climatic events, dispersals, faunal turnovers, and extinctions that shaped the European Cenozoic faunas, ultimately leading to the emergence of extant taxa. Such prominent events that affected European snake faunas include the high temperatures observed during the Paleocene-Eocene Thermal Maximum (PETM) and the Early Eocene Climatic Optimum (EECO), the cooling that triggered the “Grande Coupure” at the Eocene-Oligocene boundary, or the distinct palaeogeographic settings that arose during the formation of the “Gomphotherium Landbridge” during the Early Miocene, and the Messinian Salinity Crisis during the Miocene-Pliocene boundary (Szyndlar & Rage 2003; Rage 2013; Zaher et al. 2019; Georgalis et al. 2021; Ivanov 2022; Georgalis & Szyndlar 2022; Smith & Georgalis 2022). However, significant gaps remain from both a stratigraphic and a geographic point of view. Indeed, stratigraphically speaking, some geological epochs, such as the Paleocene and the Oligocene, are underrepresented, compared to other epochs, in the European snake fossil record (Smith & Georgalis 2022). Most notably from a geographic point of view, the Eastern portions of the continent remain notably less sampled for fossil snakes than Western and Central Europe (e.g. Ivanov 2022; Smith & Georgalis 2022).

European snake fossils have been known for over two centuries, with the earliest discoveries dating back to the early 19th century (Karg 1805). Throughout that century, notable fossil snake discoveries continued to capture the interest of European palaeontologists, including remarkable or enigmatic forms, such as the giant aquatic genus Palaeophis Owen, 1841, from England, the giant viper Laophis Owen, 1857, and Python euboicus Römer, 1870 – representing the first record of the extant genus Python Daudin, 1803, in Europe – both from Greece, as well as the constrictor Palaeopython Rochebrune, 1880, from France (Owen 1841, 1850, 1857; Meyer 1845; Römer 1870; Filhol 1877; Rochebrune 1880, 1884). The 20th century witnessed continued advancements in fossil snake discoveries in Europe, driven particularly by the comprehensive and meticulous work of Robert Hoffstetter, Jean-Claude Rage, and Zbigniew Szyndlar, who significantly enhanced our understanding of taxonomic diversity, cranial and vertebral diagnostic features, and intracolumnar variation in snakes (e.g. Hoffstetter 1939; Hoffstetter & Rage 1972; Rage 1974, 1983, 1984; Szyndlar 1984, 1991a, 1991b). In recent decades, our understanding of the taxonomic diversity and anatomy of Cenozoic fossil snakes from Europe has accelerated significantly, aided by the use of recent technologies such as micro-computed tomography (μCT) scanning (Bell et al. 2021) and by an improved knowledge of the skeletal anatomy of extant taxa (Zaher et al. 2019; Szyndlar & Georgalis 2023). Despite these advances, significant gaps remain, as many taxa have yet to be adequately described and the phylogenetic relationships of several groups are still poorly understood, hindering a full understanding of snake evolution in the European Cenozoic.

With this new volume in Comptes Rendus Palevol, we aim to address significant gaps in our knowledge of the snake fossil record during the European Cenozoic. The forthcoming contributions in this volume will encompass a range of topics, including:

– descriptions of new taxa and revisions of poorly documented taxa;

– identifications of novel anatomical features in the skull and vertebrae of fossil snakes;

– studies of articulated skeletons from Fossillagerstätte localities, enhanced by the application of micro-computed tomography (μCT) scanning;

– documentation of new fossil snake occurrences from underexplored regions of Europe;

– revised taxonomic frameworks for enigmatic and previously ambiguous extinct snake groups;

– studies of palaeobiogeography, dispersal events, extinction and survivorship dynamics of snakes across the Cenozoic of Europe, using sophisticated analytical methods.

We anticipate that this volume will provide fresh perspectives on the evolution of Cenozoic snakes in Europe, while also serving as a trigger for future research and new discoveries about these fascinating and charismatic reptiles!