EvC Forum: Extinction of Dinosaurs: Consensus Reached . . . mostly

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Topic: Extinction of Dinosaurs: Consensus Reached . . . mostly

Blue Jay

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Message 5 of 53 (549367)
03-06-2010 11:54 AM

Reply to: Message 4 by Dr Jack
03-06-2010 8:33 AM

Hi, Mr Jack.

Mr Jack writes:

The paper also, bizarely, claims that "[t]he scale of biological turnover between the Cretaceous and Paleogene is nearly unprecedented in Earth history". And supports it with a reference neatly detailing the other mass extinctions... umm?

It’s a poor choice of words, but, since that scale of turnover only happen four other times in half a billion years (and only two of those were at equal or greater intensity), I think it counts as nearly unprecedented.

I certainly wouldn’t have phrased it that way, though.

-----

Mr Jack writes:

Chicxulub happened, it explains the geological features of the K-T boundary. But it cannot be considered an answer to dinosaur extinction question until it can explain the distribution of survivors.

I'm going to have to disagree with you on this.

First, I don’t think science can really answer questions of the form, Why didn’t _____ happen?

Second , I think there are very good hypotheses about how each of those types of organisms survived: omnivory, small body size, low metabolism, and/or ability to find shelter are all considered likely explanations for why various groups survived.

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 4 by Dr Jack, posted 03-06-2010 8:33 AM		Dr Jack has replied

Replies to this message:
	Message 6 by Dr Jack, posted 03-06-2010 12:03 PM		Blue Jay has replied

Blue Jay

Member (Idle past 2719 days)

Posts: 2843

From: You couldn't pronounce it with your mouthparts

Joined: 02-04-2008

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Message 17 of 53 (549893)
03-11-2010 11:00 AM

Reply to: Message 6 by Dr Jack
03-06-2010 12:03 PM

Hi, Mr Jack.

Mr Jack writes:

Maybe, but it certainly should be able to explain what it's trying to explain - in this case why the dinosaurs died out. The impact isn't an answer to that question because it doesn't explain why other groups didn't die out and thus leaves the question unanswered.

I disagreed with it the first time you said it, and I still disagree with it now.
Why does the survival of some groups of mammals and birds invalidate the impact as a reason for the extinction of the dinosaurs?

-----

Mr Jack writes:

It is simply not possible to find clear dividing lines like that between groups which survived and groups which didn't.

Nothing in biology ever has clear dividing lines. Like everything else I’ve ever seen, there are only messy trends with a lot of noise. Why is this such a problem for you in this one instance?

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 6 by Dr Jack, posted 03-06-2010 12:03 PM		Dr Jack has replied

Replies to this message:
	Message 20 by Dr Jack, posted 03-11-2010 12:02 PM		Blue Jay has replied

Blue Jay

Member (Idle past 2719 days)

Posts: 2843

From: You couldn't pronounce it with your mouthparts

Joined: 02-04-2008

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Message 18 of 53 (549896)
03-11-2010 11:05 AM

Reply to: Message 12 by Larni
03-09-2010 1:07 PM

Hi, Larni.

Larni writes:

Birds could....I dunno, I don't suppose they could do much but they must have done something right.

Birds could fly.

As resources become sparse, the ability to travel greater distances in a shorter period of time with less effort than running gives them the advantage.

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 12 by Larni, posted 03-09-2010 1:07 PM		Larni has replied

Replies to this message:
	Message 19 by Taq, posted 03-11-2010 11:13 AM	Blue Jay has not replied
	Message 29 by Larni, posted 03-13-2010 11:42 AM	Blue Jay has seen this message but not replied

Blue Jay

Member (Idle past 2719 days)

Posts: 2843

From: You couldn't pronounce it with your mouthparts

Joined: 02-04-2008

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Message 22 of 53 (549988)
03-11-2010 9:08 PM

Reply to: Message 20 by Dr Jack
03-11-2010 12:02 PM

Hi, Mr Jack.

Mr Jack writes:

The impact is not an explaination because it doesn't explain the survival patterns.

A major disaster hit my home town about 10 years ago. Every house on one street was completely leveled, except for the house where some of our friends from church lived.

The "tornado theory" clearly explains what happened to all those houses, even though it can't explain why my friends' house was not destroyed. So, does the survival of my friends' house pose a serious problem for the "tornado theory"?

The "tornado theory" is a theory about the mechanism of destruction, not about the mechanism of survival. How can a tornado possibly explain why my friends' house survived? And, why would it have to?

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 20 by Dr Jack, posted 03-11-2010 12:02 PM		Dr Jack has replied

Replies to this message:
	Message 23 by pandion, posted 03-12-2010 1:19 AM	Blue Jay has replied
	Message 24 by Dr Jack, posted 03-12-2010 4:35 AM	Blue Jay has not replied

Blue Jay

Member (Idle past 2719 days)

Posts: 2843

From: You couldn't pronounce it with your mouthparts

Joined: 02-04-2008

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Message 25 of 53 (550043)
03-12-2010 9:29 AM

Reply to: Message 23 by pandion
03-12-2010 1:19 AM

Hi, Pandion.

pandion writes:

Is it possible that I have actually grasped your point? Naaah!

I'm... not sure.

If you're being sarcastic, use a smiley to help me out.

-----

Just in case, I do want to address one point:

pandion writes:

So you are saying that your friend's house didn't have any damage whatsoever? There were no shingles blown off? There were no windows blown out? The siding wasn't damaged?

One eave was broken off, and there were a good number of holes on one side of the building, from flying debris.

Just like the mammals and birds still suffered damage, so to speak: enantiornithiform and hesperornithiform birds, for instance, went completely extinct at the K-T, along with the Laurasian marsupials.

It is interesting to note that none of the major mammalian clades went completely extinct at the K-T, though.

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 23 by pandion, posted 03-12-2010 1:19 AM		pandion has not replied

Replies to this message:
	Message 26 by Dr Jack, posted 03-12-2010 10:18 AM		Blue Jay has replied

Blue Jay

Member (Idle past 2719 days)

Posts: 2843

From: You couldn't pronounce it with your mouthparts

Joined: 02-04-2008

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Message 27 of 53 (550050)
03-12-2010 10:34 AM

Reply to: Message 26 by Dr Jack
03-12-2010 10:18 AM

Hi, Mr Jack.

Mr Jack writes:

Hmm... aren't the "major" mamalian clades defined by their existence post K-T, so - by definition - survived?

I don't know. I've only ever heard of four "major" mammalian clades---monotremes, multituberculates, marsupials and placentals---and I'm relatively certain that all of them are found before and after the K-T.

-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.

This message is a reply to:
	Message 26 by Dr Jack, posted 03-12-2010 10:18 AM		Dr Jack has replied

Replies to this message:
	Message 28 by Dr Jack, posted 03-12-2010 10:56 AM		Blue Jay has seen this message but not replied

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