Extinct venomous mammals

[Tim Williams <twilliams_alpha@hotmail.com>]

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

ABSTRACT: "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).  Here we report evidence of a 
venom delivery apparatus in extinct mammals, documented by well-preserved 
specimens recovered from late Palaeocene rocks in Alberta, Canada.  Although 
classified within Eutheria, these mammals are phylogenetically remote from 
modern Insectivora 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 snakes in evolving salivary venoms and their delivery systems 
several times independently."

The venomous furball in question is a small pantolestid named _Bisonalveus 
browni_.  It belongs to the "order" Cimolesta, an extinct group that is 
possibly related to pangolins (Pholidota) and carnivorans (something I 
didn't know).  The _Bisonalveus_ specimens come from the Paskapoo Formation 
(late Paleocene) of Alberta.   In one specimen, the canines are preserved in 
situ, with the upper canines modified to form special venom-conducting 
teeth.

OK, so these guys didn't scuttle around the feet of dinosaurs (except for 
the avian ones), but a pretty great discovery anyway.

Cheers

Tim