Birds

[UTEOTW]

"establish feathers"

We just had a post on this one om the previous page.

http://www.baptistboard.com/ubb/ultimatebb.php/topic/66/89.html#000005

The feather is a relatively recent product in evolution that formed between 125–175 million years ago and has brought in the novel functions of insulation, display and flight. A multi-level complexity model of scale/feather morphogenesis is presented that is consistent with the developmental stages observed in embryonic chicken skin and in the different protofeathers/feather precursors recently found in fossils. As we learn
more about how molecular cascades contribute to various morphogenetic processes and how developmental pathways interact to build novel and more complex forms [51,52], we can begin to appreciate how the pressure of adaptation may act on the mechanics of signaling and development during evolution.

The full paper is at

http://www-hsc.usc.edu/~cmchuong/2000CurrOpinGenetandDev.pdf

 

[UTEOTW]

Originally posted by Helen:
Suggest you start a new thread with this one, UTE. This thread is for the birds...

Done.

I left the feather question here since it is on topic for this thread.

 

[The Galatian]

Galatian, get the breast bone turned upside down,

I'm not familiar with the argument that it's "upside down." Could you show us?

establish feathers (which have NO relation to scales!)

So we can agree that no dinosaur had feathers, but all birds have the keeled breastbone?
Are there any others you'd like to add?

provide wings, muscles, and the blood supply necessary for them.

We can't use muscles or blood vessels, since both dinosaurs and birds have them. And not only birds have wings, so we can't use them, either.

Are you sure this is all that separates dinosaurs and birds?

Add the nerve extensions and instincts necessary.

Dinosaurs have those, too. Unless you can be more specific.

Don't forget the tendons and ligaments which must attach differently.

That could be the case. Could you be specific which tendons and ligaments, and which attachments?

Change the bones from heavy to light.

You mean, perhaps hollow bones with air passages in them?

When you answer these questions, I'll make a list, and see how it matches up. You can, of course, add or remove items when you see the list. Then we can make an estimate.

 

[Helen]

Galatian you are trying to say there is no difference between the circulation pattern of a dinosaur and a bird? Are you trying to say the breast bone of a dinosaur and a bird are the same? Are you trying to say the musculature of a dinosaur is the same as a bird's? Or that the nerve connections are the same? Are you trying to say that no mutations at all were necessary to get from dinosaur to bird?

If mutations were needed, please, how many did it take?

 

[The Galatian]

Galatian you are trying to say there is no difference between the circulation pattern of a dinosaur and a bird?

I am asking you to specify which circulation patterns are found in all birds, and were never in dinosaurs. For example, if you are claiming retes only occur in birds or only occur in dinosaurs, then we have a way to specify an essential difference. Specify.

Are you trying to say the breast bone of a dinosaur and a bird are the same?

I'm asking you to specify in what measurable ways the breast bones of all birds are different than the breastbones of all dinosaurs. When you've done that, we have another factor to account for. Tell me what you think.

Are you trying to say the musculature of a dinosaur is the same as a bird's?

See above. Tell me what features of musculature are found always in one, and never in the other. That will be another feature to account for.

Or that the nerve connections are the same?

See above. If you can pull this off, we'll have quite a list to account for.

Are you trying to say that no mutations at all were necessary to get from dinosaur to bird?

Well, that's what we're trying to find out. When we know the essential differences between them, we'll be able to say.

If mutations were needed, please, how many did it take?

Depends on the number of features you can find that are always in one, and never in the other.

Let us know, and we'll be able to make an estimate. I'm not trying to mess with you here. It's not a question scientists seem to have asked, and on reflection, I think it's worth pursuing.

 

[The Galatian]

I should add...

I'm not trying to lay a trap, but there is a trap of sorts you could build for yourself. You should be very careful about laying down the essential defining characteristics of each, because if they aren't truely defining characteristics, it would mean no mutation would be required.

If you want to take some time to be sure, feel free to do it. I know I'd want to check my work carefully.

 

[Helen]

Just get me from a dinosaur to a bird, however you do it. Don't ask me to do your work for you.

 

[The Galatian]

If you can't define the difference, what makes you think there is one?

Because the transitionals are so finely graded, it's very difficult to say what is a bird and what is a dinosaur.

I'll freely admit that I can't draw the line, either.

But if you can't, and I can't, what makes you think there is one?

 

[Johnv]

I'm still waiting for an answer to my question. Why do humans and dinosaurs not appear at the same time in the fossil record?

That's not even a question supporting evolution. It's a simple question. Why can I not get a simple answer?

 

[Helen]

Galatian, if there is no difference then you don't need transitionals. Apart from that, I'll let the thread stand the way it is. Any child can see the ridiculousness and evasiveness of your responses.

 

[The Galatian]

You don't think there's a difference between primitive dinosaurs and birdlike ones? What about primitive birds and advanced ones?

If you can't even provide a clear way to distinguish all dinosaurs from all birds, what makes you think there is an essential difference?

You mentioned a breastbone. Start there. What about the breast bone of birds makes a clear difference with dinosaurs?

Then we can talk about the other differences.

 

[Helen]

Quit sidestepping, Galatian. How many mutations from a dinosaur that is called a dinosaur to a sparrow?

 

[The Galatian]

I'd say quite a lot for a highly evolved bird like a sparrow.

I thought you meant how many mutations would it take to go from a dinosaur to a bird.

Quite a different question. That would be "how many mutations to go from the most birdlike dinosaur to the most dinosaurlike bird?" As you see, it's very hard to even tell me how to distinguish the two reliably.

The Passerida are a branch of the "perching birds" or Passerine Birds, which are members of the Passiformes, which is a subgroup of one of the two major divisions of "modern birds", the Neornithes.

So that would be a rather bad example. Let's see if we can tighten the search a little. Do you think that Archaeopteryx is a bird? If so, perhaps you could tell us what features of that animal are representative of birds, but never found among the dinosaurs. You mention a deeply keeled breastbone. Is that a good feature? How about air sacs in bones?

Don't give up on this. It could be a good way to test the idea.

 

[Helen]

Quite a few mutations to get to a sparrow. OK. How many is 'quite a lot' -- a few thousand? Half a million? What are we talking about here for this highly evolved bird?

 

[The Galatian]

Quite a few mutations to get to a sparrow.

But we're trying to see how many to get from a dinosaur to a bird. Using a highly evolved bird doesn't tell us anything. It merely tells us how much birds have evolved from the that evoved from dinosaurs.

How many is 'quite a lot'

Certainly less than it took to get from a primitive reptile to Compsognathus; birds are much closer to any dinosaur than any dinosaur is to a turtle. Not long ago, they got a little T-rex hemoglobin and it turned out to be closer to that of birds than any reptile tested.

But let's get back on the question. We were trying to figure out how many mutations it would take to make a bird of a dinosaur.

I know you're uncomfortable with the process, but to do this, we have to define the dividing line between dinosaurs and birds.

You're reluctant to do it, and I would be too. It's not an easy task. But if it doesn't work out the way you like it, I wouldn't mind if you tried again.

So what features do you think are on all dinosaurs, but absent from all birds, and what features do you think are on all birds, but absent from all dinosaurs?

When you get that, we can answer the question. If you think it's impossible to define the differences rigorously, then the answer is "0".

This is why most scientists now think that birds are dinosaurs; there's no good separation between them.

Feduccian and Olson are the holdouts who think it should be spread out so that it includes thecodonts, with dinosaurs and birds having a common theocondont ancestor.

 

[Helen]

funny, I always thought a sparrow was a bird. Please feel free to get from a dinosaur to a vulture, if you like. Or an eagle. Or a penguin. Or even a dodo. What about an ostrich?

If you don't think there are any differences between a dinosaur and any of these birds, then we can leave this thread here and let any readers see where you ended up.

Up to now all you have been doing is playing word games. If you didn't want to get serious about the subject of mutations, all you had to do was say so.

 

[The Galatian]

funny, I always thought a sparrow was a bird.

I feel the goalposts shifting...

Please feel free to get from a dinosaur to a vulture, if you like. Or an eagle. Or a penguin. Or even a dodo. What about an ostrich?

All you have to do, is define a bird in terms of characteristics that differentiate birds from dinosaurs.

By now, it appears you've realized that you can't do it. And that's a good answer.

If you don't think there are any differences between a dinosaur and any of these birds,

Remember, you have to find how all dinosaurs differ from all birds, not how any particular bird differs from another.

then we can leave this thread here and let any readers see where you ended up.

I think we should throw this one open and see if anyone else would like to try the challenge. Can anyone show even one characteristic by which all birds differ from all dinosaurs? Helen and I can't do it. Can anyone else?

Up to now all you have been doing is playing word games.

If we don't define what we mean, then we can't even begin. How hard could it be to rigorously define dinosaurs as opposed to birds?

Very hard, as you seem to now realize.

If you didn't want to get serious about the subject of mutations, all you had to do was say so.

I'm very serious. Let's see if anyone else can do it.

 

[UTEOTW]

Since we don't have dinosaur genomes with which to compare, it is not a question that is to be accurately answered. In that case, all we have to go on is physical evidence at this point. Since that is where things stand, it seems to me to be a fair request to ask you to define for us what you think that differences are between birds and dinosaurs. What traits make a bird a bird and which make dinosaur a dinosaur?

Now the difficulty for you in this is that they have so many traits in common. Even worse, there are intermediate fossils that have various mixes of the traits that one would think could be used to distinguish the two. So it is very hard to make a hard and fast definition of the differences. Now this is just what one would expect if they were related as is asserted. But it is hard to explain if they are completely separate.

But, from the first page of the thread, we have found that these supposed ancestors of the birds had hearts more like birds than other reptiles, that they had lungs more like birds than other reptiles, that their blood vessels are more like birds than other reptiles and that they had feathers, up to and including asymmetric flight feathers, that are, well, like what birds have.

 

[The Galatian]

Which is why scientists now think dinosaurs and birds form a clade, with all other reptiles as the outgroup.

 

[Helen]

"more like" is not the "same as."

Aside from Galatians flat out lies about what I have said or implied (which is not uncommon for him), I leave the rest to the other readers to see what is going on. To my mind, calling birds and dinosaurs the same sort of thing is an act of desperation.

On another forum, I was asked why, if people have free choice, they choose wrong so often. The point the writer was making was that God must be stupid or incompetant or not there at all. My response included the thought that the more 'educated' and 'intelligent' the person, the more often the wrong choices seem to be made. I presume that is because common sense gets thrown out with one's pride in one's intelligence and education a good percentage of the time.

If there are any readers out there following any of this who don't feel they are intelligent enough to comment, don't worry about it. Common sense is enough to see what is going on. You can trust that. Don't let all the word play and other garbage intimidate you into thinking you don't have what it takes to know the truth or to recognize the truth when you see it.

UTE, Galatian, I'm done with this thread. You two have totally betrayed the very brains God gave you.