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Re: THE WONDERFUL WORLD OF SALAMANDERS



  From: "Nicholas R. Longrich" <longrich@phoenix.Princeton.EDU>

  > Do we really have that much good evidence on salamanders and
  > frogs? Can we even identify them past the generic level, or even
  > past the subfamily level? I've heard something to the effect that
  > there are no complete frogs known from the late K of NA.

  I am not in a position to judge on my own.
  
  Archibald doesn't say much about frogs - there is at most one frog
  species in his faunal tabulation.  He counts 8 or so species of
  salamanders in the Hell Creek and Fort Union faunas.  He claims to
  have rejected indeterminate fragments in his tabulations (that is
  why he lists no snakes, for instance).

  > scenario #1: Not a single species of frog, toad, newt, salamander,
  > caecilian etc. went extinct at the K/T boundary. They all made it
  > through. There was not any decline in the number of individuals in
  > a species, either.
  
  It is quite possible for there to have been a substantial decline in
  numbers and yet few no extinctions. (Scenario #1.5 :-)
  
  Archibald's data make no characterization of abundance, except for a
  simple binary discrimination of "rare" versus "not rare".  Thus, the
  data as presented cannot say anything about any decline in numbers,
  or lack thereof.
  
  Also, Archibald treats the presence of a Fort Union *descendent* as
  a survival, even if the older species is not actually attested in
  the FU.

  > scenario #2: Frogs, toads, newts, salamanders, etc. got a good
  > thrashing at the K/T for the same reason(s) as dinosaurs.  Most
  > species went extinct- in fact, only a relatively few individuals
  > from ONE species of each genera/subfamily (as the case may be)
  > managed to survive. In the depopulated post K/T world, however,
  > their large reproductive potential allowed the individuals to
  > repopulate or even create new species in the vacuum left. Very
  > soon after the K/T, frogs and salamanders were thriving and
  >  healthy.
  > 
  > These are just for the sake of argument, of course.  My question
  > is: is the evidence of fossil amphibians good enough to
  > distinguish between these two extreme scenarios?

  I am not sure.  I think Archibald would say the evidence tends to
  favor scenario #1 or #1.5.

  Another issue, of course is whether pattern of salamander survival
  is restricted to the Hell Creek and Lance, or is worldwide.  There
  is no evidence on that issue yet.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.