[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: SV: Shaking up the bird family tree

There is also the issue of whether or not "flight gain" and "flight loss" are really single characters - some cases of flight gain and/or loss may be effectively more parsimonious than others.



On Jun 27, 2008, at 2:34 PM, Tommy Tyrberg wrote:

The problem here is that to argue that flight is lost, you must have
1) a single gaining of flight, 2) loss of flight in ostriches, 3) loss
of flight in rheas, and 4) loss of flight in the cassowary/kiwi/emu
clade. This is more steps than a simpler explanation in which tinamous
gained flight after the whole lost it. A tad more parsimonious, rather.


 Jaime A. Headden

Being parsimonious does not necessarily mean the same as being right. The problem here is that we know that cases of bird lineages becoming flightless are extremely common (I could cite a couple of hundred instances), while we know only "a single gaining of flight" somewhere back in the Jurassic. Using the same argument I could just as easily argue that several rail taxa are primitively flightless since they consist of one flighted and several flightless species. Since Steadman has actually worked a lot on flightless rails he should really know better.

It is interesting to note that the location of hoatzin and seriemas is
still rather shaky.

Tommy Tytberg

Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280-0181 habib@jhmi.edu