Mammal-specific scorpion neurotoxins

[Kevin Thiele]

>P.S.  Are mammal-specific neurotoxins of scorpions effective against
>certain clades of mammals, or against mammals in general?  If the latter,
>then such toxins could have easily developed during the very long Mesozoic
>history of mammals.

Must it be the case that mammal-specific neurotoxins evolved in response to
mammals? I believe that funnel-web spider (Atrax: Australia) venom is highly
toxic to primates but much less so to other mammals - but this surely is
purely accidental, since primates (Homo only) are very late arrivals to
Australia.

Cheers - k


-----Original Message-----
From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On Behalf
Of Ken Kinman
Sent: Wednesday, 8 February 2006 9:24 AM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: [TAXACOM] RE: mammals morphologically evoluated a lot since the
Ceno zoïcum, invertebrates did not.Why?

On Tue, 7 Feb 2006 11:30:19 -0500, Fet, Victor <fet at MARSHALL.EDU> wrote:

For scorpions, it is always taken for granted but might not be true....

there are indeed major groups of scorpions which did not survive K-T
extinction....

 the best example in scorpion context is evolution of mammal-specific
neurotoxins, obviously Cenozoic!
*********************************************************
Hi Victor,
     I would certainly agree that many major scorpion groups died out
*before* the K-T extinction (most well before the Cretaceous even began).  I
suppose some families of scorpions could have gone extinct the end of the
Cretaceous, but with so few fossils (mostly from the Middle Cretaceous?),
how would you know that the end-Cretaceous extinction did them in?  Whatever
scorpion families existed at the end of the Cretaceous, I still suspect a
majority of them survived (although with fewer genera than before the
extinction).  Not a *catastrophic* extinction like that which wiped out the
vast majority of families of birds at the end of the Cretaceous.  Birds just
barely made it through.
  ---Cheers,
           Ken Kinman
P.S.  Are mammal-specific neurotoxins of scorpions effective against certain
clades of mammals, or against mammals in general?  If the latter, then such
toxins could have easily developed during the very long Mesozoic history of
mammals.