Re: Age Abstractions

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

At 21:07 2007-06-20, evelyn sobielski wrote:


> And what is suspect about this one is the locality.
> There probably was little more inhospitable terrain in
> the earliest Paleogene than the
> southwestern/south-central US... if the present
> estimates about impact angle of the Chixculub bolide
> are correct, it received far more of the immediate
> consequences (and ejecta) and relatively more of the
> mid-term consequences than most other places on Earth.
> The area in question must have been literally
> cauterized.
>
> If he'd had dug up his find on Chatham Island, *that*
> would be interesting indeed. But this is simply
> suspect.

I don't agree with that. True, being within a couple of thousand 
kilometers from Chicxulub would certainly have been lethal (ejecta 
blanket, IR flash, superheated steam shockwave etc), but the zone 
beyond that may actually have been the least bad place on Earth to 
be. The reason for this is that only relatively low energy ejecta can 
re-enter close to the original impact. Being near the antipode of 
Yucatan (e g Madagascar or India) would be much worse. The IR 
radiation from re-entering ejecta there would be lethal to almost 
anything not underground or underwater. However the early Paleocene 
of the western US is uniquely well known, so it seems highly unlikely 
that any surviving dinosaurs there wouldn't have been found long age. 
Chatham Islands however also seems unlikely as a refugium. Recent 
work in New Zealand suggests that the effects of Chicxulub were very 
bad there too. I would suggest Antarctica as the most likely place. 
It does seem that a lot of the extant dinosaurs originated/survived there.

Tommy Tyrberg