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Re: "What did dinosaurs really look like..."



At 11:23 PM 20/08/00 -0500, max salas wrote:
But we can make educated guesses based on what we know about them and what
we know about our extant environment: For example, predatory animals are
more modest in color than herbivores, this is more evident in birds than in
everything else, and why is that?, well, they tend to live in flocks and
showing off to get status or a mate is more important than being eaten.
(numbers are a great defense for a species, if not for the individuals)
check out parrots, chicken, peasants, etc.

Well, I don't want to comment on the colouration of the rural poor, but I'm afraid this isn't very accurate ornithology. First of all, the statement that "predatory animals are more modest in color than herbivores" really doesn't hold up. Although it is true that many frugivorous and nectarivorous birds are brightly-coloured, there are also numerous rather plain ones (eg many honeyeaters [Meliphagidae]). Seed-eaters (which are certainly herbivores too) include many dull-coloured species (eg sparrows). On the other hand, some predatory species such as pittas and bush-shrikes are extremely colourful (and I am incuding insect- and snail-eaters as predators here - they certainly aren't herbivores!). Diet may be a very poor predictor of colour (compare the generally-dull Old World warblers (Sylviinae) with the generally-colourful New World warblers (Paruliinae).


Of course even dividing birds into predators and herbivores isn't too easy as many birds (eg woodpeckers) are omnivorous.

"Living in flocks" isn't much of guide either. Actually very few birds live in flocks year-round anyway, and flocking does not correlate at all with bright colour. Many of the most brilliantly-coloured birds do not flock, and many dull-coloured species do.

In fact I am not sure at all that the life-styles of living birds, most of which occupy niches that must be quite unlike those of non-avian dinosaurs, can give us much of a guide to dinosaur colours. Only a handful of birds are, for example, reasonably large and terrestrial. Even among the ratites, male ostriches are brightly- or at least strikingly-coloured while rheas, which are quite similar ecologically, are not.

However, I am not much bothered by restorations that make at least a few basic assumptions drawn from birds - eg colour vision, dorsal countershading (given, for example, that almost all pelagic seabirds are black, white or grey in various combinations I see no reason why pelagic pterosaurs could not have been similar, though I do not recall seeing anyone paint a black-and-white Pteranodon) or bright colours or markings on such presumed display structures as the heads of oviraptorids or the casques of tapejarids.


--
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
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