Re: Extinct venomous mammals

[Phil Bigelow <bigelowp@juno.com>]

The most recent issue of _Nature_ won't be put on the shelf here for
another week (!) so I have to ask:

Is the venom conductor a longitudinal fossa alongside the exterior side
of the canine (primitive), or is it a (more evolved) internal channel?

<pb>
--

On Wed, 22 Jun 2005 15:10:38 -0500 Tim Williams
<twilliams_alpha@hotmail.com> writes:
> 
> 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
> 
> 
> 
>