Re: Bird-like dinosaurs

[Ursula Grigg <Ursula.Grigg@xxxxxxxxxx>]

Good afternoon!
    I have just walked along the Geology Department hall with a 
step-stool, and looked at the dinosaur panorama displayed just below 
the ceiling. It's the Zallinger picture all right, and it has a 
narrow border at the bottom, dividing it by geological period; 
unfortunately the border is largely concealed by the frame.
    There's another version in the paleo lab, divided between 4 
plastic boxes, also hung just below the ceiling. It is much 
cruder, but has a deep, bold border with the time information on it, 
at the bottom. The boxes break up the sequence nicely, but are all 
the same size, perverting the time scale.    
    I think any display needs a separate time chart, plus some visual 
division by periods, with a brief note on each. And of course hang it 
where it's easy to see.
    Is there any need to go into the exact lineages of birds? There 
seems to be a lot still unknown, and development of birds may have 
been a slow process. Since skeletons model the body shape and actions 
of vertebrates, it should be possible to indicate relationships in 
the way their reconstructions are presented. 
    There's always a clash between modern biological classification, 
in which birds are easily separated from reptiles, and the 
paleontological one. In the latter, the lapse of time plays a part 
and organisms may be named arbitrarily, either to pigeonhole them 
until someone can get back to them, or because nobody believes one 
taxon can persist for 'that many' million years.
    
    [I'm a biologist traversing the time scale watching ostracods 
change; I would particularly like to know if Cretaceous birds and/or 
their ancestors migrated]

                            Ursula Grigg