Richard Fox of the University of Alberta has uncovered fossilized "dagger-like" teeth for two mammals in Central Alberta. The previously known Bisonalveus browni - a shrewlike animal - and a second, unnamed animal exhibit the characteristics needed for venom delivery.
The teeth - which have no corresponding groove on the lower jaw - would have been used to stab prey (most likely beetles). The presence of these teeth suggest that this predation strategy may have been more common than previously thought during the Palaeocene.
There are only four mammals on the planet today that use venom - the Caribbean Solenodon the North American Short-tailed Shrew, the Eurasian Water Shrew, and Australia's Duck-billed Platypus.
Read the LETTER at Nature.com