Causus is a genus of vipers found only in sub-Saharan Africa. It is a group considered to be among the most primitive members of the family Viperidae based on head scalation, oviparity, venom apparatus, and because they have round pupils.[2][3] However, this is contradicted by recent molecular studies.[4][5] Seven species are currently recognized.[6][7] They are commonly known as night adders.[2][3] Like all other vipers, they are venomous.
^McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Herpetologists' League. 511 pp. ISBN1-893777-00-6 (series). ISBN1-893777-01-4 (volume).
^ abMallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Krieger Publishing Company. Malabar, Florida. 359 pp. ISBN0-89464-877-2.
^ abSpawls S, Branch B. 1995. The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. ISBN0-88359-029-8.
^Nagy ZT, Vidal N, Vences M, Branch WR, Pauwels OSG, Wink M, Joger U. 2005. Molecular systematics of African Colubroidea (Squamata: Serpentes) In: Huber BA, Sinclair BJ, Lampe KH (Eds.). African Biodiversity: Molecules, Organisms, Ecosystems. Proc. 5th Intern. Symp. Trop. Biol. Museum Koenig, Bonn, pp. 221-228.
^Wüster W, Peppin L, Pook CE, Walker DE. 2008. A nesting of vipers: phylogeny and historical biogeography of the Viperidae (Squamata: Serpentes). Molecular Phylogenetics and Evolution 49: 445-459.
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