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



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This was actually the subject of my (unpublished, alas) PhD Thesis, in which I identified (at least to my satisfaction) a number of toe and limb modifications common to passerine tree-climbing birds from a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