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FLYING-->FLIGHTLESS-->FLYING



Quizzed by Tom Holtz, John Jackson writes...

> Modern insects and birds are not a good analogy for this reason:  
> early flightless dino/birds went from one form to another and then 
> back to the earlier one:
>    flightless -> flying -> flightless

> modern flightless birds and insects effectively just do this:
>    flying -> flightless

How do you know this? There are numerous extant clades with closely 
related volant and non-volant taxa, and even SPECIES where some 
inviduals are volant and others are not. It is entirely possible, 
theoretically of course, for some extant volant taxa to have had a 
non-volant ancestor. Modern insects and birds are therefore entirely 
appropriate analogues for Jurassic-Cretaceous theropods.

"The essence of science is that theories and models must be tested, 
rigorously" (Shipman 1998)

DARREN NAISH
darren.naish@port.ac.uk