Reply
Fri 30 Mar, 2007 07:15 am
An interesting article suggests that the extinction of the dinosaurs did not contribute greatly to the diversity of mammals.
The Article wrote:At the time of the dinosaur demise, mammals were small, ranging in size between shrews and cats. The long-held view has been that once the dinosaurs were gone, mammals were suddenly free to exploit new food sources and habitats, and as a result they produced a burst of new species.
The new study says that happened to some extent, but that the new species led to evolutionary dead ends. In contrast, no such burst was found for the ancestors of modern-day mammals like rodents, cats, horses, elephants and people.
Instead, they showed an initial burst between 100 million about 85 million years ago, with another between about 55 million and 35 million year ago, researchers report in Thursday's issue of the journal Nature.
It's a very interesting article, also noting the increasing use of DNA, rather than just fossil evidence, as a historic marker. And the remaining mystery of what actually DID cause known episodes of increased Mammal diversity (even before the Dino's died out).
This article seems a little conflicting. First it says the extinstion didn't produce a flurry of new mammel species.
Quote:The big dinosaur extinction of 65 million years ago didn't produce a flurry of new species in the ancestry of modern mammals after all, says a huge study that challenges a long-standing theory.
But then it said it did.
Quote:The new study says that happened to some extent, but that the new species led to evolutionary dead ends. In contrast, no such burst was found for the ancestors of modern-day mammals like rodents, cats, horses, elephants and people.
Well so what if they led to a dead end. Something came along and filled the environmental niches left vacated by the dinosaurs.
The extinction of dinosaurs was a benefit, except when it wasn't. Classic evolutionary thinking.
real life wrote:The extinction of dinosaurs was a benefit, except when it wasn't. Classic evolutionary thinking.
Far better than classical Biblical mythology thinking that has no scientific backing.
Is it just me, or was that article badly written? Or am I just stupid...?
Quincy wrote:Is it just me, or was that article badly written? Or am I just stupid...?
I think their point is new species that led to modern day mammals didn't come about right after the extinction event, as believed, but later. But there were still new species emerging that filled the vacated niches.
xingu wrote:Quincy wrote:Is it just me, or was that article badly written? Or am I just stupid...?
I think their point is new species that led to modern day mammals didn't come about right after the extinction event, as believed, but later. But there were still new species emerging that filled the vacated niches.
The basic idea has always been that certain events could change the environment sufficiently to allow the sudden rapid expansion of new species to fill the new environment.
The KT extinction event seemed like an obvious candidate for such an event not only because of the physical changes to the environment due to the impact, but also be cause such a large successful group of animals weren't around any more to fill their usual niche (Dinosaurs). It also makes an compelling story, "The mighty dinosaurs died, which set the stage for the rise of the mammals". But apparently that's not true.
Mammals had undergone greater diversification before and after the KT extinction.
If such an obvious event like the KT extinction wasn't associated with unusual mammal expansion, and yet two other times before and after the KT were, it really makes you wonder just what causes these rapid diversifications.
There was another thread recently where, I believe it was Gungasnake,you all know gungasnake?APRIL. The article was about teaching kids with a roll of toilet paper unrolled and with time and species appearnaces on the roll. My contribution was that , for many years, scientists have not thought this way. Instead, the appearances of , say, mammals , never corresponded with the KT , In fact, mammals actually predate dinosaurs . SO, the toilet paper model should, in order to be accurate, be done in twosies. One roll to show time and another , broken apart series of rolls to show the arrival and departure of the major animal groups.
ROSBORNE-how dare you, the major dead mammals that didnt make it throuth the KT or only made it through to the late PAleocene are ALL based on fossils. WE have no bases to test the DNA "time clock" with these major groups , since we only have 3 mammal subclasses now , when ,during the Triassic and Jurassic, we had ,maybe 7 or 8,
AND, a number of these were some big mommas who just didnt have the general bauplan to make it through subsequent environmental changes
I dont think Id just jump on the new bandwagon just yet. This is based upon a huge cladogram done by whatzizname at the NYM Nat Hist and , just like were still messing with the theory that there were 2 KT and T bolide strikes, theres much beard scratching to take place.
Im of the climatic change in the early Paleocene , because of the Paleocene aged euxinic shales around the globe and climatic evidence from several sedimentary deposits. The boli9de didnt cause this but, the bolide was a good "start point" if nothing else..
rlQuote:The extinction of dinosaurs was a benefit, except when it wasn't. Classic evolutionary thinking.
. All hypotheses are, at least based upon a mish mash of data. Science is not fortunate enough, like the CReationists, to befree of any data or evidence. AS many have said while holding up Creationism to closer inspection
"The only field work you guys have ever engaged in, is to hunt for an ARK on Mt Arrarat" APRIL
Farmerrman wrote:ROSBORNE-how dare you, the major dead mammals that didnt make it throuth the KT or only made it through to the late PAleocene are ALL based on fossils.
I'm sure the article was referring only to the DNA history of existing mammals which are available for analysis.
You didn't really think that I (or the article) implied that the DNA being tested was from Dinosaurs did you?
The article wrote:The timing of that first period of evolutionary development generally agrees with the conclusions of some previous studies of mammal DNA, which argue for a much earlier origin of some mammal lineages than the fossil record does.
The article wrote:The study's family tree includes 4,510 species, more than 99 percent of mammal species covered by an authoritative listing published in 1993. (Nearly 300 species have since been added to the listing, but the researchers said that doesn't affect their study's conclusions.) To construct it, the researchers combined previously published work that relied on analysis of DNA, fossils, anatomy and other information.
For some reason, the link to the article isn't working any more (probably an April Fool's Joke by someone). You an find it on CNN.com under the science section.
Ha, this is funny... when I quote posts by Farmerrman, the system changes the quote to "Davy Crockett"
I think someone is playing an Aprril fools joke on AA2K.
Hahahaha, it also translates AA2K into "Nauthty Web Site" and other stuff (little guys with afro's).
I have to mis-spell words intentionally to avoid the prank
<b>Davy Crockett</b> wrote:rlQuote:The extinction of Barney was a benefit, except when it wasn't. Classic evolutionary thinking.
. All hypotheses are, at least based upon a mish mash of data. Science is not fortunate enough, like the CReationists, to befree of any data or evidence. AS many have said while holding up Creationism to closer inspection
"The only field work you guys have ever engaged in, is to hunt for an ARK on Mt Arrarat" <img>
rosborne979, Apparently its a moving thing. When I woke up this AM and read the mammals versus DIna Sawars post it didnt include the word Barney.Its been gradually unfolding , thats pretty neat. Somebody's working on SUnday amd passover eve , just cause its APril 1
PS, oh yeh, that line is "captured" from "A FLOCK OF DODO'S". I bought it and read it at your behest. Its a very quick read, a very short book , but also very "in yer face"
<b>Davy Crockett</b> wrote:PS, oh yeh, that line is "captured" from "A FLOCK OF DODO'S". I bought it and read it at your behest. Its a very quick read, a very short book , but also very "in yer face"
Hi Davy, what line is borrowed from Flock of Dodo's?
Im sorry, I meant the line that said
"The only field work you (Creationists ) have ever done was to hunt for an Ark on Mt Arrarat"
I thought you read the book. Its gonna be required reading .
Stumble It!
Tweet This
Bookmark on Delicious
Share on Facebook
Share on MySpace