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Re: Archaeopteryx flight




David Marjanovic wrote:

- lack of a perching foot, unlike *Confuciusornis* (and all basal
Pygostylia);

In a lot of discussions on tree-living birds and theropods (of the non-avian variety) the terms "arboreal", "scansorial" and "perching" tend to get conflated.


By a "perching foot" I suppose you mean (in anisodactyl perchers) a pes that has a reversed and distal hallux that is opposable to the other three digits allowing a greater degree of prehensile ability in order to grasp branches. A specialized perching foot allows a bird to adopt a vertical "hands-free" posture when sitting on a branch. This is a very useful thing for a bird to be able to do, since (with one notable exception) the anatomy of modern birds is entirely "hands-free". At least in the sense that the digits on the manus are not free and useful for grasping.

Lack of a specialized perching foot would *not* prevent _Archaeopteryx_ from climbing trunks or branches, since it still had a mobile and fairly prehensile manus tipped with nice sharp claws. Ditto for the pes, though this probably had less prehensile ability than the manus.


- apparent lack of high trees (is it possible that the few ginkgo trunks
that are sometimes mentioned are driftwood?);

Even if these bits of ginkgo were driftwood (and I'm not saying that they were), then this implies the ginkgoes came from somewhere in the vicinity of _Archaeopteryx_'s watery graveyard - perhaps from a neighbouring island. At any rate, there were trees of some sort within a radius capable of being reached by _Archaeopteryx_, even considering its weak flying abilities.



- probable lack of sufficient flight abilities.

Explain to me why "probable lack of sufficient flight abilities" (whatever that means) implies that _Archaeopteryx_ couldn't climb trees?



Tim












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