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

Re: Secondarily Flightless Question

Just a quick answer, I'm sure you will get more will get more extensive responses later.

Terror birds and ratites show so many accumulated characters (synapomophies) shared with other birds, that they FAR outweigh any reversals associated with the loss of flight. Basal maniraptorans, on the other hand, had not yet accumulated so many unique characters (apomorphies) that they would necessarily outweigh reversals associated with flight loss.

To put it more simply, basal maniraptorans all look fairly similar, and any unique characters are minor. So, the reversals required by Greg Paul's neoflightless hypothesis minor - they could have lost the very few traits that would cause them to come out as birds in a phylogenetic analysis. In the case of terror birds and ratites, however, we see very few true reversals, and many, many unique characters shared with flying birds.

Hope this helps.

On Wednesday, September 11, 2002, at 01:42  AM, Rob Gay wrote:

I've got a question for those of you more familiar with avian phylogeny than
When running a cladogram (pretty extensive), do terror birds fall out as
birds? If so (and I imagine they do), do they all clump together (I think I
know the answer here too, but I'm not too sure)? How about ratites?
If this produces a phylogeny that shows "terror birds" are just flightless
birds, along with ratites, and they lost the ability to fly, why wouldn't
postulated neoflightless dinosaurs (dromeosaurs, enigmasaurs, etc.) show up
as neoflightless dinosaurs in large analyses? I mean, its argued that such
flight loss occurs so quickly, its not recorded in the fossil record, and
the descendents of such flightless birds are not interoperated
correctly...why does this only work for the animals at the base of aves, and
not more derived members of the clade? Maybe I'm not understanding something

Student of Geology
400 E. McConnell Drive #11
Northern Arizona University
Flagstaff, Az. 86001
AIM: TarryAGoat

John Conway, Palaeoartist

"All art is quite useless." - Oscar Wilde

Systematic ramblings: http://homepage.mac.com/john_conway/
Palaeoart: http://homepage.mac.com/john_conway/_palaeoart.html