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Sun 22 Jun, 2008 04:24 pm
I haven't read the link, but, birds are descended from some types of dinosaurs.
The thing was driven by information as is all biology. Most likely is that some sort of genetic re-engineering was involved going from dinosaurs to birds. It's provably impossible to get from dinosaurs to birds via any combination of mutation and selection.
I wouldn't be surprised if a large portion of genetic code from our ancestors (or a chicken's ancestors) still remains in the modern genome. However, I am skeptical that we will ever be able to isolate the pieces necessary to recreate ancient animals (at least with any degree of accuracy).
We might be able to create chickens with tails or chickens with teeth and tails and claws, but I don't think we would have a dinosaur. I think we would have a modernosaur.
Like Naomi Campbell you mean?
i do have proof:
see they are dinosaurs and chickens AT THE SAME TIME!
Yeah, the answer to the age-old question of which came first, the chicken or the egg, it's obvious: the dinosaur!
gungasnake wrote:It's provably impossible to get from dinosaurs to birds via any combination of mutation and selection.
What a jackass.
Prove it, clown, if it's as iron-clad certain as you claim.
Well, Horner likes to act like a gadfly sometimes, as in his contention that Tyrannosaurus rex was an obligate scavenger. One should take his statements, particularly those to the mainstream press, with a big block o' salt.
With that said, if one were to somehow obtain a largely-complete genome that was "missing" parts and figured out a way to piece it together aside from those parts, birds are definitely the way to go for 'filling it in'. Jurassic Park had amphibians providing that extra stuff, which is silly concerning the relatedness of the creatures.
Similarly, it is entirely plausible that "dinosaur"-ish genes which determined dinosaur-ish phenotypes could be modified or switched on/off to create a more 'basal' bird. But Horner would seem to be exaggerating quite a bit concerning deriving a dinosaur, as in something with about the same genotype as something which actually lived in the Jurassic, from an emu. The evo-devo stuff is interesting, but its exclusivity, here implied as the sole thing making the difference between birds and dinosaurs, would be very much contested. In fact, the exact extent to which it has played a role in evolution is one of those fun hotly-debated issues that is a real controversy in science. Oh, and in case anyone is getting the wrong idea, I would say it's consensus that modifying development has been a very important way in which evolutionary changes/novelty has come about, even though its relative importance compared to other mutations is still debated.
Hmm, perhaps I should provide a caveat: if one were to strip away and modify the development of modern birds and arrive at what they think was likely the ancestral form, they *could* come up with a dinosaur-bird-thing which is very like or near-identical to something which actually lived millions of years ago.
But an actual tyrannosaur from modern bird DNA seems a bit silly to me, as that's a separate but closely-related lineage of theropods. They could probably design a theropod-like dinosaur, but I have trouble seeing how they could make a statistical argument for it being accurate without some real tyrannosaur DNA.
Shirakawasuna wrote:
But an actual tyrannosaur from modern bird DNA seems a bit silly to me,
They've actually managed to sequence some of the proteins from that tyrannosaur leg bone you might have read about with the soft tissue inside, and the proteins were all but identical to those of a chicken.
The trex was basically just a big chicken with sharp teeth.
gungasnake wrote:Shirakawasuna wrote:
But an actual tyrannosaur from modern bird DNA seems a bit silly to me,
They've actually managed to sequence some of the proteins from that tyrannosaur leg bone you might have read about with the soft tissue inside, and the proteins were all but identical to those of a chicken.
Just like human proteins are all but identical to those of a mouse.
I guess humans are just big mice with opposable thumbs.
Quote:The new studies provide strong support for the hotly debated claims that organic material previously extracted from the T. rex's leg bone is original dinosaur soft tissue that somehow escaped fossilization...
In real life....
...that escaped fossilization by means of not being anywhere remotely close to millions of years old...
I recall my great grandfather's tales of running with dinosaurs when he was a boy. Then he went off to trade school. When he came home, for some reason he was not clear about, the big beasties were all gone. So, yeah, many of them have not had time to fossilize.
oy, Apparently you didnt read the facts about the "soft tissue" . It was a substance that was encased within a carbonate matrix all crystalized. The keragen deposits in coal beds are very similar, where nodules of waxy like material lie within caverns calleds "vugs"
The chemical and physical states of a fossil bera no information about its limit in age. There are fossilized ambers from the Paleozoic, and these deposits will melt like tar balls when exposed to heta. They have no crystal structure and are pure organic material. Coal wax, petroleum, sour gas, and now , by the miracles of acid etching, we have relict soft tissue in a T rex kneecap.
ALL comfortably aged at about the CAMPANIAN via U/Th disequilibrium methods.
(No Bibles were disturbed in the U/Th dating)
gunga may be confused in thinking that"if its old, its gotta be really hard rock". Not true at all, some of the rocks of the Early Ordovician are still clays and are used for making brick. Chalk cliffs of Cretaceous (chalk) ages are just that, chalk, not consolidated and indurated. Many early formations contain minerals that are soft and unstructured, they can retain an almost paleo soil appearnce. The same is with many deposits of minerals, petroleum like tar, Permian coal layers with actual paraffin wax layers, and resins and organic fluids of ages that go back over 400 million years. The act of consolidation and induration involves a process like "cooking" by differential P/T and uniaxial compression. If such cooking does not occur, then many deposits of organic acids or waxes or even soap like materials can be left as fossil evidence. Animal fossils are usually produced by chemical replacement nmechanisms.As Thompson et al found, the lack of complete replacement of the material within the upper leg bones was a function of a chemical reaction that had only achieved a certain level of completeness
When gunga lets us know that he doesnt understand paleo material science, he tries to pooh pooh what he doesnt understand. Fortunately hes realktively safe because noone has the time or inclination to do a detailed explanation of mechanisms. However, I can assure him that Ill try to let him know at least where hes dead wrong.
farmerman wrote:gunga may be confused in thinking that"if its old, its gotta be really hard rock". Not true at all, some of the rocks of the Early Ordovician are still clays and are used for making brick. Chalk cliffs of Cretaceous (chalk) ages are just that, chalk, not consolidated and indurated. Many early formations contain minerals that are soft and unstructured, they can retain an almost paleo soil appearnce. The same is with many deposits of minerals, petroleum like tar, Permian coal layers with actual paraffin wax layers, and resins and organic fluids of ages that go back over 400 million years. The act of consolidation and induration involves a process like "cooking" by differential P/T and uniaxial compression. If such cooking does not occur, then many deposits of organic acids or waxes or even soap like materials can be left as fossil evidence. Animal fossils are usually produced by chemical replacement nmechanisms.As Thompson et al found, the lack of complete replacement of the material within the upper leg bones was a function of a chemical reaction that had only achieved a certain level of completeness
When gunga lets us know that he doesnt understand paleo material science, he tries to pooh pooh what he doesnt understand. Fortunately hes realktively safe because noone has the time or inclination to do a detailed explanation of mechanisms. However, I can assure him that Ill try to let him know at least where hes dead wrong.
Do you ever feel that you are a soldier fighting a never-ending wave of barbarism and ignorance, Farmerperson?
Bone is not the most porous stuff in the world, but it IS porous. The idea of anything like this surviving inside bone for 70,000,000 years is a total joke; it would have to have never rained in Montana or the Dakotas in all that time.
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