Re: DINOSAUR digest 3384

[Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>]

Jerzy Dyczkowski wrote:


>Finally - one day after fire, plants begin to regrow
>providing food. I assume dinosaurs could survive some
>weeks without food (and eggs might much longer).

It's not that simple. The early successional vegetation after a fire is 
very different from what came before ("fern spike"). It normally takes at 
least a century before the vegetation is back to climax. If the fire is in 
a habitat where fire does not occur naturally (e. g. rainforest) the 
vegetation may NEVER return to the original state since many species will 
not have seeds that survive long enough.

>Of alternative theories: amphibians and freshwater
>fish are very suspectible to acid rain. Small birds
>are very suspectible to smoke (use of canaries in coal
>mines). In modern forest fires, birds drop dead from
>smoke.

Actually it is methane canaries are used to detect. Incidentally many birds 
are attracted by fire. For example I've several times seen raptors hunt 
insects and small animals flushed by brushfires in Australia, they don't 
seem to be much discommoded by the smoke.

>I would first ask some meteorologist/astronomer. How
>would real atmosphere react? Would falling microscopic
>ejecta indeed deliver single heat pulse? I suggest
>atmospheric currents would produce uneven fall and
>evaporating water would quickly block radiation from
>reaching ground. This I don't know. Nor I see
>discussed there.

Atmospheric currents are completely irrelevant to ballistic objects. The 
infall would indeed be uneven, but this is because the debris is not 
ejected evenly from the impact site.
Evaporating water would indeed block radiation if it forms clouds. This 
requires cooling - which can't happen when there is intense irradiation 
from above.


>I think this means that. Heat needed to kill large
>animals would also dry surrounding vegetation and
>start a fire (actually fire would burst first, due to
>heat capacity of big animal).

Nonsense. Animals will die (of burns and/or heat stress)long before e. g. 
wood catches fire. Wood will start burning when the surface is heated to ca 
300-400 degrees centigrade. Most animals won't survive having their skin 
heated much over 100 degrees centigrade.

>they list avian lineages surviving KT and duly
>say that many DON'T contain any burrowers.

>In most of remaining clades, burrowing is restricted
>to few derived taxa so likely evolved recently. This
>applies to eg. ratites (kiwi).

First remember that we really know very little about Cretaceous crown-group 
birds since there are almost no fossils. Nesting and sheltering habits of 
ghost-lineages are not easily determined!
Note however that in anseriforms some of the most plesiomorphic extant 
forms (tree-ducks) are hole-nesters as are a few species of tinamoes (the 
most plesiomorphic paleognaths, crevice-nesters might be a better term in 
this case). Passerines are probably primitively hole-nesting etc. The only 
real problem as I see it are the galliforms which does not contain any 
hole-nesting species today (though some galliforms do make snow-burrows).

>Nitpicking, on top of this they lump hole nesting with
>burrowing. In this case, tree hole is no protection
>from heat radiation enough to ignite a whole tree.

See above. Essentially every unprotected animal would be dead long before a 
whole tree catches fire.

Tommy Tyrberg