Comments on The Iapetus Beat: A Review of the Chicxulub impact extinction link

If the asteroid was respsonsible for mass death, t...

2010-03-11T18:41:33.933-06:00

If the asteroid was respsonsible for mass death, there is one question that has not been answered:
Where's the bone pile? Give me just one instance where athe remains of a group of dinosaurs, or any other life form, coincides with the impact.

Suvrat, thanks for the link. I hadn't seen it ...

2010-03-11T09:20:37.028-06:00

Suvrat, thanks for the link. I hadn't seen it yet and Nature Geoscience is one of the only journals I can't fully access online. I hope this is corrected soon because it's becoming increasingly relevant. I'll look up the article next time I'm at the library.

Thanks for the response, Bryan. Fair enough. I pro...

2010-03-11T09:18:17.681-06:00

Thanks for the response, Bryan. Fair enough. I probably oversimplified your stance (that's why I encouraged readers to link to your post). My point is that if the timing holds up (i.e., if Keller and others remain the minority view and evidence builds against them), then the case is pretty tight for the Chicxulub-extinction link -- as tight as many things in geology that we take for granted and which, of course, are occasionally overturned.

Hey CM, I just found your post (and your blog for ...

2010-03-11T01:12:53.900-06:00

Hey CM, I just found your post (and your blog for that matter. A belated welcome to the geoblogosphere). I will add you to my blog-roll when I update it next.

However, the significance of the Signor-Lipps effect is not that we can't build a case for an extinction mechanism (clearly we can, as this has been done). It is that we can't adequately falsify any of the proposed mechanisms. Add to this other factors (extirpation, stratigraphic completeness, chronostratigraphic constraints on resolution, etc.) and the problems become even more difficult to address.

If we continue to ignore the significance of these observed phenomena, the discussion will lead down a circular web of intractable arguments, and scientific progress suffers. I think that eventually, with sufficient research, there will be techniques to surmount the Signor-Lipps effect. However, until we reach that point, it is premature to say there is conclusive proof for ANY mechanism being the primary cause.

I also wouldn't necessarily characterize Norman MacLeod as an opponent of the link between Chicxulub and the dinosaur extinction. My impression of his research is that he is one of the few workers engaging in productive research involving extinction studies (in that he is trying to surmount the Signor-Lipps effect).

Anyway, thanks for the link to my post. I look forward to reading, and learning, about planetary geology.

good one! there is another paper in Nature which brings out latitudinal differences in extinction patterns, also supporting the asteroid theory.