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Re: Dinosaurs and birds



Anthony Docimo writes:

could maniraptors (not birds) with feathered arms have had an advantage over maniraptors lacking feathers on their arms, when it comes to those turning manuvers and clearing obstacles?

Another advantage of 'winged' forelimbs in a fast runner would be to help streamline the folded forelimbs into the body wall to reduce drag. In this instance the 'wings' would be kept tightly folded while running.


Many extant animals go through an arborial phase as juveniles, which they grow out of (Komodo monitors come to mind). I envisage the juveniles of some dromaeosaurs (like *Saurornithosaurus*) spending a lot of time in trees, avoiding larger predators and perhaps chasing small arborial prey. The recurved second toe would have made a handy grapple, while relatively large forelimb proportions and low body mass could even have made them semi-volant (or at least capable of parachuting in case of a fall). Upon reaching adult size, they could have switched to a more cursorial lifestyle, in which the forelimbs (and perhaps 'wing' fans) were too small for flight (or even gliding), and were perhaps used in the manner I suggested earlier (and as display and/or brooding devices). The recurved toe claws could have then functioned more as predatory tools than for climbing.

The question would then be whether such behaviour resulted in some early maniraptor lineages becoming paedomorphic and retaining volancy their entire life (eventually becoming 'birds'), or whether such behaviour was a case of ontogeny recapitulating phylogeny (ie. flight being ancestral to dromaeosaurs, and being reflected in their juvenile stage).

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Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com
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