Exquisitely Preserved Fossil Snakes of Messel: Insight into the Evolution, Biogeography, Habitat Preferences and Sensory Ecology of Early Boas

Agustín Scanferla,Krister T Smith

doi:10.3390/d12030100

Abstract

Our knowledge of early evolution of snakes is improving, but all that we can infer about the evolution of modern clades of snakes such as boas (Booidea) is still based on isolated bones. Here, we resolve the phylogenetic relationships of Eoconstrictor fischeri comb. nov. and other booids from the early-middle Eocene of Messel (Germany), the best-known fossil snake assemblage yet discovered. Our combined analyses demonstrate an affinity of Eoconstrictor with Neotropical boas, thus entailing a South America-to-Europe dispersal event. Other booid species from Messel are related to different New World clades, reinforcing the cosmopolitan nature of the Messel booid fauna. Our analyses indicate that Eoconstrictor was a terrestrial, medium- to large-bodied snake that bore labial pit organs in the upper jaw, the earliest evidence that the visual system in snakes incorporated the infrared spectrum. Evaluation of the known palaeobiology of Eoconstrictor provides no evidence that pit organs played a role in the predator–prey relations of this stem boid. At the same time, the morphological diversity of Messel booids reflects the occupation of several terrestrial macrohabitats, and even in the earliest booid community the relation between pit organs and body size is similar to that seen in booids today.

Highlights

Snakes of the clade Boidae are arguably among the most charismatic species of living reptiles
In this paper we describe the anatomy of this species based on Computed Tomography (CT) data sets
Since several booid lineages have their oldest, or near-oldest, records in Messel, this leads to the appearance that they originated in Europe and dispersed to the New World, rather than the other way around

Summary

Introduction

Snakes of the clade Boidae (boas, anacondas, emerald boas) are arguably among the most charismatic species of living reptiles. They are one of the first offshoots of that part of the snake tree that capture and ingest prey much larger than their own head through an arsenal of anatomical and behavioural features including constriction [1], macrostomy [2], and infrared detection as an integral part of their visual system [3,4]. The study of several exquisitely preserved skeletons of the booid snake Eoconstrictor fischeri from the Eocene Konservat-Lagerstätte of Messel (Germany) provides considerable new insight into the biology of early boas. In this paper we describe the anatomy of this species based on CT data sets

Methods

Results

Discussion

Conclusion