Abstract
Many advanced snakes use fangs—specialized teeth associated with a venom gland1,2—to introduce venom into prey or attacker. Various front- and rear-fanged groups are recognized, according to whether their fangs are positioned anterior (for example cobras and vipers) or posterior (for example grass snakes) in the upper jaw3,4,5. A fundamental controversy in snake evolution is whether or not front and rear fangs share the same evolutionary and developmental origin3,4,5,6,7,8,9. Resolving this controversy could identify a major evolutionary transition underlying the massive radiation of advanced snakes, and the associated developmental events. Here we examine this issue by visualizing the tooth-forming epithelium in the upper jaw of 96 snake embryos, covering eight species. We use the sonic hedgehog gene as a marker10,11,12,13, and three-dimensionally reconstruct the development in 41 of the embryos. We show that front fangs develop from the posterior end of the upper jaw, and are strikingly similar in morphogenesis to rear fangs. This is consistent with their being homologous. In front-fanged snakes, the anterior part of the upper jaw lacks sonic hedgehog expression, and ontogenetic allometry displaces the fang from its posterior developmental origin to its adult front position—consistent with an ancestral posterior position of the front fang. In rear-fanged snakes, the fangs develop from an independent posterior dental lamina and retain their posterior position. In light of our findings, we put forward a new model for the evolution of snake fangs: a posterior subregion of the tooth-forming epithelium became developmentally uncoupled from the remaining dentition, which allowed the posterior teeth to evolve independently and in close association with the venom gland, becoming highly modified in different lineages. This developmental event could have facilitated the massive radiation of advanced snakes in the Cenozoic era, resulting in the spectacular diversity of snakes seen today6,14,15.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout




Similar content being viewed by others
References
Kochva, E. The origin of snakes and evolution of the venom apparatus. Toxicon 25, 65–106 (1987)
Kochva, E. in Biology of the Reptilia Vol. 8 (eds Gans, C. & Gans, K. A.) 43–162 (Academic Press, 1978)
Jackson, K. The evolution of venom-delivery systems in snakes. Zool. J. Linn. Soc. 137, 337–354 (2003)
Kardong, K. V. Protovipers and the evolution of snake fangs. Evolution 33, 433–443 (1979)
Jackson, K. The evolution of venom-conducting fangs: insights from developmental biology. Toxicon 49, 975–981 (2007)
Vidal, N. Colubroid systematics: Evidence for an early appearance of the venom apparatus followed by extensive evolutionary tinkering. J. Toxicol. Toxin Rev. 21, 21–41 (2002)
Jackson, K. & Fritts, T. H. Evidence from tooth surface morphology for a posterior maxillary origin of the proteroglyph fang. Amphibia-Reptilia 16, 273–288 (1995)
Kardong, K. V. Evolutionary patterns in advanced snakes. Am. Zool. 20, 269–282 (1980)
Kardong, K. V. The evolution of the venom apparatus in snakes from colubrids to viperids and elapids. Mem. Inst. Butantan 46, 105–118 (1982)
Cobourne, M. T. & Sharpe, P. T. Sonic hedgehog signaling and the developing tooth. Curr. Top. Dev. Biol. 65, 255–287 (2004)
Fraser, G. J., Berkovitz, B. K., Graham, A. & Smith, M. M. Gene deployment for tooth replacement in the rainbow trout (Oncorhynchus mykiss): a developmental model for evolution of the osteichthyan dentition. Evol. Dev. 8, 446–457 (2006)
Fraser, G. J., Graham, A. & Smith, M. M. Developmental and evolutionary origins of the vertebrate dentition: molecular controls for spatio-temporal organisation of tooth sites in osteichthyans. J. Exp. Zool. B 306B, 183–203 (2006)
Yamanaka, A., Yasui, K., Sonomura, T. & Uemura, M. Development of heterodont dentition in house shrew (Suncus murinus). Eur. J. Oral Sci. 115, 433–440 (2007)
Kuch, U., Muller, J., Modden, C. & Mebs, D. Snake fangs from the Lower Miocene of Germany: Evolutionary stability of perfect weapons. Naturwissenschaften 93, 84–87 (2006)
Fry, B. G. et al. Evolution of an arsenal: Structural and functional diversification of the venom system in the advanced snakes (Caenophidia). Mol. Cell. Proteomics 7, 215–246 (2007)
Vidal, N. et al. The phylogeny and classification of caenophidian snakes inferred from seven nuclear protein-coding genes. C. R. Biol. 330, 182–187 (2007)
Young, B. & Kardong, K. Dentitional surface features in snakes (Reptilia: Serpentes). Amphibia-Reptilia 17, 261–276 (1996)
Frazzetta, T. H. Studies on the morphology and function of the skull in the Boidae (Serpentes). Part II. Morphology and function of the jaw apparatus in Python sebae and Python molurus . J. Morphol. 118, 217–296 (1966)
Bogert, C. M. Dentitional phenomena in cobras and other elapids with notes on adaptive modifications of fangs. Bull. Am. Mus. Nat. Hist. 131, 285–357 (1943)
Cope, E. D. in US National Museum Annual Report for 1898 153–1270 (US Govt Print. Off., 1900)
Boulenger, G. A. Remarks on the dentition of snakes and on the evolution of the poison-fangs. Proc. Zool. Soc. Lond. 40, 614–616 (1896)
Anthony, J. Essai sur l'evolution anatomique de l'appareil venimeux des Ophidiens. Ann. Sci. Nat. Zool. 17, 7–53 (1955)
Shayer-Wollberg, M. & Kochva, E. Embryonic development of the venom apparatus in Causus rhombeatus (Viperidae, Ophidida). Herpetologica 23, 249–259 (1967)
Kochva, E. Development of the venom gland and the trigeminal muscles in Vipera palaestinae . Acta Anat. 52, 49–89 (1963)
Ovadia, M. Embryonic development of Duvernoy’s gland in the snake Natrix tessellata (Colubridae). Copeia 1984, 516–521 (1984)
Gygax, P. Entwicklung, Bau und Funktion der Giftdrüsse (Duvernoy’s gland) von Natrix tessellata . Acta Trop. 28, 226–274 (1971)
Buchtova, M. et al. Embryonic development of Python sebae - II: Craniofacial microscopic anatomy, cell proliferation and apoptosis. Zoology 110, 231–251 (2007)
Reshef, R. Ontogenetic Mechanisms of Teeth and Oral Gland Development in Snakes - A Possible Contribution to the Understanding of Evolutionary Processes in Reptiles. PhD thesis, Univ. Tel-Aviv. (1994)
Reshef, R., Ovadia, M., Wollberg, M. & Kochva, E. Snake yolk sac as a site for in vivo organ incubation: a new method in the research of snake embryo development. J. Exp. Zool. 270, 538–546 (1994)
Martin, H. Recherches sur le développement de l’appareil venimeux de la Vipera aspis . C. R. Assoc. Anat. 1, 56–66 (1899)
Acknowledgements
We thank the following persons and institutions who helped us or contributed material used in this study: J. W. Arntzen, M. Brittijn, M. de Boer, R. van Deutekom, N. Dunstan, K. Van Egmond, P. L. Y. Fung, I. Gavrilov, W. Getreuer, J. Hanken, E. Heida, I. Ineich, T. de Jong, K. V. Kardong, M. Lautenbach, J. Losos, D. Millar, C. Pepermans, J. M. Richman, J. Rosado, R. de Ruiter, P. Schilperoord, M. M. Smith, S. Soubzmaigne, N. Vidal, E. M. Wielhouwer, J. Woltering, National Museum of Natural History Naturalis Leiden, Reptilezoo Serpo, Muséum National d'Histoire Naturelle Paris, AQIS, DEH, APCG and DWLBC (Australia). This work received funding from the following sources: a Toptalent grant from the Netherlands Organization for Scientific Research (NWO; F.J.V.), a Smart Mix grant from the Dutch government (M.K.R.), a Valorisation grant from the Dutch Technology Foundation (STW; M.K.R., F.J.V., B.G.F.), the Curatoren fund (F.J.V.), the LUSTRA fund (F.J.V.), the Australian Research Council and the Australian Academy of Science (B.G.F.), DEST-ISL (B.G.F.), Whitman College (K.J.), a NWO visitors grant (M.K.R., B.G.F.) and the Leiden University Fund (F.J.V.).
Author Contributions F.J.V.: study concept and design; embryo and skull collection, acquisition and processing; probe synthesis; in situ hybridizations; histology; figures; paper. J.F.A.: three-dimensional reconstructions, figures. K.J.: scanning electron microscopy. R.R.: study concept, ablation experiment, histology. E.K.: study concept, embryological data. K.V., I.v.d.B., M.v.A.: in situ hybridizations, histology. M.A.G.d.B.: probe design, in situ hybridizations. A.B.: Naja embryo collection. P.J.M.: supply of Naja material. B.G.F.: study concept, supply of Causus material. A.W.: provision of laboratory space. E.B., F.W.: morphometric analyses. M.K.R. (project leader): study concept and design, provision of funding and laboratory space.
Author information
Authors and Affiliations
Corresponding author
Supplementary information
Supplementary information
The file contains Supplementary Figures 1-7 and Supplementary Tables 1-6. Figure 1 shows a summary of our results. The other figures include additional shh expression data, additional histology data (including our ablation experiment), the results of our scanning electronic microscopy, and the linear regression analyses of the ontogenetic allometric measurements of the developing front fangs. The 6 tables display all material used in this study, and the results of our statistical analyses of the ontogenetic allometry. (PDF 4872 kb)
Rights and permissions
About this article
Cite this article
Vonk, F., Admiraal, J., Jackson, K. et al. Evolutionary origin and development of snake fangs. Nature 454, 630–633 (2008). https://doi.org/10.1038/nature07178
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/nature07178