Re: pterosaurs, pre-K/T theropods, and Certhiidae

[Ronald Orenstein <ornstn@rogers.com>]

At 09:43 AM 30/12/02 -0800, Jaime A. Headden wrote:
> As for *Certhia*, there are numerous treecreepers and honeycreepers, as
> well as most all other arboreal piciforms, that are well-suited to
> harvesting on the trunks of trees, either wood, investing food storage,
> grubs, or the soft pulpy cork beneath the bark. This appears to be enabled
> largely through the pedal and tail design, with paired bracing raches in
> the tail, and zygodactyle feet with specialized claws.

This statement is a bit misleading.  First of all, as I'm sure Jaime knows, 
Certhia, other treecreepers and honeycreepers are passeriformes, not 
piciformes, and have anisodactyl rather than zygodactyl feet.  By and 
large, honeycreepers (in either the New World tanager assemblage or the 
Hawaiian honeycreepers, which are cardueline finches) are not really 
trunk-climbers (exceptions from each group are the Giant Conebill Oreomanes 
fraseri and the Hawaiian Creeper Oreomystis mana).  Secondly, not all 
trunk-climbing birds have stiffened tail feathers - nuthatches, Australian 
treecreepers (Climacteridae) and the Nuthatch-Vanga of Madagascar 
(Hypositta corallirostris) do not and depend entirely on modifications of 
the pelvic apparatus, including toes and legs, for support (as do even some 
birds with stiffened rectrices, such as pygmy parrots (Micropsitta) which 
climb up trunks woodpecker-fashion using the tail as a brace and the legs 
spread widely apart, but climb down headfirst with the tail held free of 
the bark, rather like a nuthatch).

This was actually the subject of my (unpublished, alas) PhD Thesis, in 
which I identified (at least to my satisfaction) a number of toe and limb 
modifications common to passerine tree-climbing birds from a number of 
independent lineages.  I do not know if any of these would translate to 
dinosaurs or pterosaurs as they may all be related to the inability of 
these birds to use their front limbs to assist in climbing, so that the 
forces acting on the hind limb elements may well be quite different from 
those in a truly quadrupedal climber.


--
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@rogers.com