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First evidence of a venom delivery apparatus in extinct mammals


Numerous non-mammalian vertebrates have evolved lethal venoms to aid either in securing prey or as protection from predators, but modern mammals that use venoms in these ways are rare, including only the duck-billed platypus (Ornithorhynchus), the Caribbean Solenodon, and a few shrews (Soricidae) (Order Insectivora)1. Here we report evidence of a venom delivery apparatus in extinct mammals, documented by well-preserved specimens recovered from late Palaeocene rocks in Alberta, Canada2,3. Although classified within Eutheria, these mammals are phylogenetically remote from modern Insectivora4 and have evolved specialized teeth as salivary venom delivery systems (VDSs) that differ markedly from one another and from those of Solenodon and shrews. Our discoveries therefore show that mammals have been much more flexible in the evolution of VDSs than previously believed, contradicting currently held notions that modern insectivorans are representative of the supposedly limited role of salivary venoms in mammalian history. Evidently, small predatory eutherians have paralleled colubroid snakes5 in evolving salivary venoms and their delivery systems several times independently.

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Figure 1: Bisonalveus browni , specimen UALVP 43114.
Figure 2: Bisonalveus browni.

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We thank Y. Sun for fossil preparation, D. Spivak for technical assistance, M. Caldwell for use of photographic equipment, and K. Gao, K. Soehn, G. Stonley, M. Webb and G. Youzwyshyn for field assistance. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the University of Alberta.

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Correspondence to Richard C. Fox.

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Fox, R., Scott, C. First evidence of a venom delivery apparatus in extinct mammals. Nature 435, 1091–1093 (2005).

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