Arboreal or Scansorial? Of course defining where one ends and the other
begins may be difficult when you're dealing with the grey area in
between.
One of the problems we have in trying to assess this whole issue is that we
have no real modern analogue to an arboreal bird ancestor - that is, a
primitively flightless arboreal biped (I exclude the very different body
forms of apes and sifakas). The closet we get are tree kangaroos. Even
among birds the only truly flightless bird I can think of that is even
semi-arboreal (and it is hardly even that) is the Kakapo, which again is
presumably wildly different from a bird ancestor in climbing
technique. Without such an analogue I think we have an even greater
difficulty than usual deciding what such an ancestor is likely to have in
the way of adaptations - and thus it my be very hard to recognize, other
than through phylogenetic analysis that avoids speculating about behaviour.
--
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2 mailto:ornstn@home.com