September 01, 2002
Yet Another Dinosaur Death Theory!
Posted by Ellen at September 01, 2002 10:27 AM
Here is more of an in-depth article on how temperature change killed the dinosaurs.
eMail this entry!
That's an in-depth article? How many words could I use to write a brief article? Would it be more than one?
Anyway, it's pretty poorly thought-out, although whether this is the fault of the scientist or the reporter is hard to say.
The only actual news in this piece is the oxygen isotope data showing a temperature drop correlating with the extinction of dinosaur species in Alberta. I'm not saying that's not a nice result, but it gets rather stretched in the rest of the article.
There's no direct evidence that dinosaurs were cold-blooded. People assume they were because extant reptilian species are cold-blooded, but birds and dinosaurs share a common, reptilian ancestor (it no longer appears that birds evolved from dinosaurs) and birds are warm blooded. Many observations of dinosaur bones and growth-rates suggest that they had at least some warm blooded character, although it might be slightly different to mammalian physiology. There are dinosaur fossils in Antartica. It wasn't ice-bound when they formed, but it was at a high lattitude. Clearly at least some dinosaurs could survive outside the temperate and tropical zones.
It's unlikely that the temperature change killed the animals, it's more likely to have changed the ecosystem they lived in in ways that made them less well adapted. What's not clear from the article is the time scale of the temperature decline. If it took several million years, why didn't species adapt and recolonise the new landscape?
There is an obvious cause for the climate change - the Deccan Traps flood basalt eruption. It's dissapointing that the implications of this observation aren't related to that event. It's also not clear (presumably unknown at the moment) whether this was a localised climate change and local extinctions, or whether these rocks are representative of the global environment.
Dinosaurs were not the only group of species to go extinct at the K-T boundary - many marine species also go extinct at around the same time. It's not clear how temperature and rainfall changes would affect marine organisms.
It has been argued for a long time that the K-T extinction starts before the impact event, and even that it continues afterwards. The data are so uncertain (this is most stratigraphic dating, but deciding which precise layer a large dino fossil belongs to is hard, radiological dating is also too uncertain on the time scales involved). Longer time scales favour the flood basalt or climate change theories, short time scales favour the impact event. There are also studies suggesting that mass extinctions happen very quickly (I think they got on down below 100,000 years), so any single data point by itself doesn't really decide the issue.
Of course its a piss poor article:) Once a journalist nabs a 'story' they try to write something interesting that to them and the 'normal' attention range human can stand. :)
You should write for a science journal, you are chock full of interesting info!
the site was fucking shit, it was so boring. it was like watching grass grow for a whole fucking year, the site orginsers were a groupe of fucking pansies, who have never been laied in there life.
thats all i have to say