Snake fangs from the Lower Miocene of Germany: evolutionary stability of perfect weapons

Abstract

There is a general consensus that most of today's nonvenomous snakes are descendants of venomous snakes that lost their venomous capabilities secondarily. This implies that the evolutionary history of venomous snakes and their venom apparatus should be older than the current evidence from the fossil record. We compared some of the oldest-known fossil snake fangs from the Lower Miocene of Germany with those of modern viperids and elapids and found their morphology to be indistinguishable from the modern forms. The primary function of recent elapid and viperid snake fangs is to facilitate the extremely rapid, stab-like application of highly toxic venoms. Our findings therefore indicate that the other components of the venom-delivery system of Early Miocene vipers and elapids were also highly developed, and that these snakes used their venom in the same way as their modern relatives. Thus, the fossil record supports the view that snakes used their venoms to rapidly subdue prey long before the mid-Tertiary onset of the global environmental changes that seem to have supported the successful radiation of venomous snakes.

Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations

“…However, a hard upper bound (of 30 Myr following Sanders & Lee, 2008) was placed on this divergence to prevent overestimation of divergence dates through over‐parameterization (Sanderson, 2003). These calibration constraints are consistent with the oldest unambiguous elapid fossils: isolated proteroglyphous fangs (Kuch et al. , 2006) that appear primitive with respect to modern elapids in retaining a longer opening on the venom groove (Sanders & Lee, 2008) and date the divergence of elapids from other colubroids at sometime before 20–23 Ma, with the hydrophiine–elapine divergence necessarily occurring afterwards.…”

Early Miocene herpetofaunas from the Greek localities of Aliveri and Karydia – bridging a gap in the knowledge of amphibians and reptiles from the early Neogene of southeastern Europe

“…This mode of venom canal development is typical for viperids (Jackson 2002;Zahradnicek et al 2008). The fangs of elapid snakes differ by the presence of a distinct anterior groove connecting entrance and discharge orifices (Kuch et al 2006). The distinct lateral grooves which stretch along the entire length of the fragment are rather unusual in viperids although short lateral grooves frequently occur in both crotalines and viperines at the vicinity of the fang base (see Figure 2 in Ivanov 1999;MI, pers.…”

Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades

“…Although the snakes in these two families are similar in that they have front-fanged venom systems, they arose independently from non-venomous snake ancestors (Knight and Mindell 1994). Based on fossil venom fangs from the Lower Miocene, Kuch et al (2006) dated the evolution of both Viperidae and Elapidae from the Early Cenozoic, thus stating that both clades evolved at the same time and before colubroid radiations of Miocene. However, studies inferring divergence times within snakes suggested that viperids diverged from colubroids between 60.9 and 43.0 million years ago (Rage et al 1992;Wiens et al 2006b).…”