2011-05-14 04:41:31Birds have wings


I have always wondered why the birds survived the climatic changes of the past when the dinasours didn't.

I suddenly realised that birds have wings and dinasours don't - birds can migrate more effectivly than dinasours.

Sorry, I'm a slow person.

I guess birds might survive the next extinction event as well.

We have airplanes, so don't worry.

- Attenborough Explores Our Fragile World (2009)

2011-05-14 06:16:10Some dinosaurs had wings
John Cook

I think a large factor was body size. I seem to recall reading somewhere that large species were wiped out when smaller species survived. Here in Australia, all the mega fauna died out while smaller marsupials flourished.
2011-05-14 07:19:47


The question is off-base: I think it's commonly believed that birds are descended from dinosaurs. I've even heard it stated that birds ARE dinosaurs.

2011-05-14 15:20:52


>I think a large factor was body size

You might be right. I watched the Attenborough documentary, and he mentioned a sea bird which flew all the way from UK to Norway to get food - in a day. Intriguing story.

According to Attenborough, birds fishing for local pray struggle to survive in UK, when local fish species disappear due to warmer water.

Same story in Norway btw - some sea birds are diminishing due to lack of food, but I don't know if this is due to warming waters (ongoing study).

2011-05-14 16:25:21


Rather more baffling is how crocodiles survived, they saw the Dinosaurs in and out.  I wonder if.........

2011-05-15 01:57:11


>Rather more baffling is how crocodiles survived, they saw the Dinosaurs in and out.  I wonder if.........

Always anoying when somebody points to contradicting facts to an argument ;-)

Perhaps the dinasours didn't die out due to a changing climate after all, or crocodiles survived because they can cool of more effectively. Well, I would like to know, out of curiosity :-)

2011-05-15 02:11:01


Last I heard, the main issue with the dinosaurs was a traumatic event: an asteroid that raised enough smoke & dust to block out the sun for a couple of weeks.

Crocodiles can easily hang out in a hole for a couple of weeks, with no problem. Especially after a big meal.

2011-05-15 02:20:29


In Australia, the megafauna extinction seems to attributed to the arrival of humans, 50k years ago. The dinosaurs were wiped out about 65 Million years ago. From the wiki article:


Dinosaurs are a diverse group of animals that were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period (about 230 million years ago) until the end of the Cretaceous (about 65 million years ago). The extinction of most dinosaur species occurred during the Cretaceous–Tertiary extinction event. The fossil record indicates that birds evolved within theropod dinosaurs during the Jurassic period. Some of them survived the Cretaceous–Tertiary extinction event, including the ancestors of all modern birds. Consequently, in modern classification systems, birds are considered a type of dinosaur—the only group of which that has survived to the present day.[1][2]

2011-05-15 02:28:39
Alex C


The formation of the Deccan Traps before the impact likely had an effect as well, with global temperatures cooling due to sulfur dioxide emissions from the feature.  The traps would have been affecting the climate for several tens of thousands of years.

As to crocodiles, they did not begin to strictly appear until about 10 million years after the KT extinction event (the taxonomic family, at least) during the Eocene.  Alligators, on the other hand, have been around for 200+ million years.  As Neal said, they have a slow metabolism, so it's indeed likely that they could survive longer and on less.  I'm not sure about the other adaptations they have acquired - they're quite resilient.

2011-05-15 02:35:08


>Last I heard, the main issue with the dinosaurs was a traumatic event: an asteroid that raised enough smoke & dust to block out the sun for a couple of weeks.

It might be right, but several extinction events seem to correlate to high levels of CO2 (relative to past levels of CO2):


I guess there are different answer to each event.

2011-05-15 02:36:25
Alex C


I have also heard that dinosaurs were warm blooded, which may have been a disadvantage to them during the extended period of global dimming.  It would fit better with the idea that birds are warm blooded, and other reptiles are not.  I'm not sure, I remember a comment that Potholer54 had left in one of his most recent videos to another user that tried to correct what he thought was an error in the video (pertinent time ~6:30-on).  The comment unfortunately is not public any more.

2011-05-15 02:38:56
Alex C


Actually, 8:20-on is a better example of what I'm talking about.  Of course, the entire 6:30-on period covers almost the entire topic.

2011-05-15 03:04:31
Tom Curtis


I think the key thing is body size.  The larger the body, the less efficient it is at cooling because of volume to skin area ratios.  Large dinosaurs probably maintained constant body temperatures from normal muscle activity, giving them the advantages of warm bloodedness (homeothermy) without the costs.  In fact, to avoid over heating they probably did not have the feathers typical of small carniverous dinosaurs.  The problem with this is if there where a sudden and sustained plunge in temperature, the the large dinosaurs would have little capability of thermo regulation, but would require high internal body temperatures for survival.  Small feathered dinosaurs including birds, and mammals where able to regulate body temperatures and therefore could survive a sudden winter if they could get enough food.  That none of the small dinosaurs survived was just luck of the draw given the number of extinctions.


Large cold blooded animals would not be as adversly effected.  They are capable of long periods of torpor and so have some chance of surviving an unexpected winter.  Amphibious cold blooded reptiles have a further advantage in that water temperatures, particularly sea temperatures would not vary nearly as much as land temperatures.


I would argue that it was cold that caused the K-T extinction rather than a CO2 driven heat because the real winners where the small warm blooded creatures, ie, creatures that could maintain normal activity in cold conditions.  Cold blooded creatures, of course, not only can go into a torpor, but cannot avoid it.  Had it been excessive heat that did in the dinosaurs (equally dangerous for gigantotherms), the cold blooded creatures would have been able to maintain similar activity to the warm blooded creatures without the energy costs.  Consequently they would have dominated teh recovery.


(There you go, five years of Creation-Evolution debates finally paid of ;) )