Birds

[UTEOTW]

An interesting discovery showing another connection between birds and their dinosaur ancestors. In this case, it shows that a theropod dinosaurs also had air sacs in their bones for breathing just as birds do.

http://www.livescience.com/animalworld/050713_dino_bird.html

For more than three decades, scientists have seriously pondered the idea that birds are today's dinosaurs. The theory was put on solid footing in 1996 with the discovery of a well preserved, small and feathered dinosaur named sinosauropterx.

Other studies have since suggested that while an adult T. rex likely had scales, its young may have been covered in downy feathers.

Yet paleontologists had long thought that dinosaurs were cold-blooded, like reptiles. A reptile's simple heart puts only low amounts of oxygen in its blood -- not the right mix in the recipe of flight.

Modern computerized tomography (CT) scans of dinosaur chest cavities five years ago found the apparent remnants of complex, four-chambered hearts more like mammals and birds.

Earlier this year, rare soft tissue of a T. rex showed its blood vessels were similar to those of an ostrich.

Meanwhile, sketchy evidence in recent years had suggested dinosaur bones might contain air cavities. Still, some experts contended dinosaurs breathed more like crocodiles.

In the new study, O'Connor and his colleague, Leon Claessens of Harvard University, examined Majungatholus atopus, a recently discovered primitive theropod that is several yards long. They found cavities in its vertebral bones similar to those found in birds.

They found that "the pulmonary system of meat-eating dinosaurs such as T. rex in fact shares many structural similarities with that of modern birds," Claessens said.

And from the actual paper.

Birds are unique among living vertebrates in possessing pneumaticity of the postcranial skeleton, with invasion of bone by the pulmonary air-sac system. The avian respiratory system includes high-compliance air sacs that ventilate a dorsally fixed, non-expanding parabronchial lung. Caudally positioned abdominal and thoracic air sacs are critical components of the avian aspiration pump, facilitating flow-through ventilation of the lung and near-constant airflow during both inspiration and expiration, highlighting a design optimized for efficient gas exchange. Postcranial skeletal pneumaticity has also been reported in numerous extinct archosaurs including non-avian theropod dinosaurs and Archaeopteryx. However, the relationship between osseous pneumaticity and the evolution of the avian respiratory apparatus has long remained ambiguous. Here we report, on the basis of a comparative analysis of region-specific pneumaticity with extant birds, evidence for cervical and abdominal air-sac systems in non-avian theropods, along with thoracic skeletal prerequisites of an avian-style aspiration pump. The early acquisition of this system among theropods is demonstrated by examination of an exceptional new specimen of Majungatholus atopus, documenting these features in a taxon only distantly related to birds. Taken together, these specializations imply the existence of the basic avian pulmonary Bauplan in basal neotheropods, indicating that flow-through ventilation of the lung is not restricted to birds but is probably a general theropod characteristic.

O'Connor & Claessens (2005) Nature 436, 253-256.

 

[ASLANSPAL]

The most dangerous bird...I think these probably
evolved(oops!)into eagles

http://www.marshalls-art.com/images/ipaleo/paleopg10/Titanus1.jpg

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[Helen]

I'm curious as to how many mutations you think it would have taken to get a dinosaur to turn into a bird, UTE.

 

[Paul of Eugene]

Ute, did the sources specifically include T-REX within the catagory of dinosaurs with hollow bones that participate in the oxygination of the blood? 'cause that might explain that small chest which seemingly wouldn't support an adequate lungful of air for such a mighty beast . . .

 

[The Galatian]

The article says that ventilation in avian lungs goes both ways. In fact, it goes only one way, unlike the usual "both ways" breathing in most other vertebrates.

The avian lung is like a single alveolus, and the respiratory path is like the collateral ventilation that occurs in other vertbrates when bronchioles are blocked. It is much more efficient than the usual way.

 

[UTEOTW]

Another intersting find having to do with birds and the feather question.

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

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 Galatian]

Very good link. I was shown some time ago, that the scutes, but not other scales, can be induced to form feathers by genetic manipulations.

Scutes were present in dinosaurs, but apparently not in therapsids.

Which would explain why mammals don't have feathers, even if some of them have scales.

 

[Helen]

Again, how many mutations did it take to get from dinosaur to bird, please?

 

[The Galatian]

How many hairs did St. Paul have on his head, please?

You don't know? Well, that must mean St. Paul didn't exist.

We can't hide God in the gaps of our knowledge. We can only say that the evidence in our possession at this time overwhelmingly says that birds evolved from dinosaurs.

Could that change? Sure. But until it does, science will go with the evidence we have.

So far, it's been a very reliable system.

 

[UTEOTW]

What kind of a question is that? Moving the goalposts?

Of course, it might actually be possible to one day answer that question. I have read of where in the process of tracing phylogenies through genetics, it is possible to reconstruct the original DNA sequence which evolved into the various forms seen in the extant species. In the future when many more species have been fully sequenced, it might be possible to start determining some of the DNA sequences of the ancestors. Not a whole genome, mind you, but it may be possible to reconstruct some of the more important genes and trace how they changed with time. But we're not there yet.

 

[Helen]

My point, UTE, is that there is no way mutations, which DELETE function could produce a bird from a dinosaur.

How many? First, you have to go downhill from the dinosaur to get to the bird, since expressed mutations result in lost function. But the question of how many mutations has nothing to do with the number of hairs on anyone's head. That's a Galation idiocy.

Evolution says that a series of mutations would have resulted in the changes from dinosaur to bird. So how many mutations? What did they do? What evidence do we have that mutations can do this?

These are extraordinarily relevant questions which are totally ignored by evolution apologists.

 

[Johnv]

Originally posted by Helen:
My point, UTE, is that there is no way mutations, which DELETE function could produce a bird from a dinosaur.

Where is the scientific evidence for the claim that genetic mutation ONLY results in a deletion of functions? In fact, a "mutation" is any change in the DNA that changes the function of the gene. Fruit flies that have over time been exposed to acidic conditions have developed genetic mutations that give them the ability to live in the new conditions, to the point where their unchanged ancestors cannot live in those same conditions.

These are extraordinarily relevant questions which are totally ignored by evolution apologists.

What about the fact that dinosaurs and humans don't appear in the fossil record at the same time? They appear at different times. And that's not even addressing the evolution/creation issue. Yet the YEC crowd insist, without evidence, that these two creations existed at the same time, even though their claim is not supported by the fossil record.

[ July 26, 2005, 01:33 PM: Message edited by: Johnv ]

 

[Helen]

Dinosaurs and humans do not appear in the same places. They required absolutely different living conditions. But the fact is they did live at the same time as multiple evidences show, including the Chinese records, Egyptian references, etc. Carvings and drawings in Australia, on Roman and Greek pottery and friezes and such also bear quiet testimony.

John, mutations do delete function. That is sometimes helpful to various species, but it does not change the fact that function itself is deleted on genetic/cellular level.

Evolutionary change requires mutations that increase enzyme specificity, create regulatory proteins, transport systems, etc. Examples of these types of mutations are what evolutionists have totally failed to produce. So, for example, an enzyme's ability to degrade nylon is simply the result of a reduction of specificity for that enzyme, enabling it to use a substrate it previously could not use. This could be considered beneficial if there is an advantage for the organism to degrade nylon. But, this, in no way, provides a genetic explanation of how that enzyme's original specificity was formed. Yet evolution claims to account for exactly that, a mechanism of how enzyme specificity originated, not how it became less. Evolution must start at bottom of Dawkins' Mount Improbable, not at the top.

 

[Johnv]

Originally posted by Helen:
Dinosaurs and humans do not appear in the same places.

That's not correct. Humans and dinosaurs do appear in some of the same palces, just not at the same time in the fossil record.

They required absolutely different living conditions.

That's completely incorrect. Most dinosaurs were the size of humans or smaller, and the conditions they lived in were often similar to present day conditions. Most dinosaurs lived in temparate conifer forests, savannahs, etc, similar to the conditions that humans enjoy.

But the fact is they did live at the same time as multiple evidences show, including the Chinese records, Egyptian references, etc. Carvings and drawings in Australia, on Roman and Greek pottery and friezes and such also bear quiet testimony.

None of those depict dinosaurs. If that were true, then fossils found in those regions would resemble the drawings. Also, dinosuar fossils found in those regions would date to date range as human remains.

Evolutionary change requires mutations that increase enzyme specificity, create regulatory proteins, transport systems, etc.

It does? It seems to me that every time a new discovery is found, the YEC'ers raise the bar. Why is that?

Examples of these types of mutations are what evolutionists have totally failed to produce.

And if they can, what will the YEC retort be? Just curious as to what the new bar will be.

 

[Helen]

That's not 'raising the bar.' That is what mutations have to do for evolution to happen.

They don't do that.

 

[The Galatian]

Let's try it a different way, Helen. I gather we agree that we can know things happened, even if we don't know every detail.

So let's look at your question again...

Again, how many mutations did it take to get from dinosaur to bird, please?

So we need to know how many mutations did it take to get from the most birdlike dinosaur to the most dinosaur-like bird.

We may not know the exact transitionals, but we can come pretty close. So let's try.

There's some question about what exactly is the dividing line between the two. So the first thing we need to do is define them.

I'll take your list of characteristics that are found in all dinosaurs, but not in any birds, and the list of all characteristics found in birds, and not in any dinosaurs.

Then we can see how much mutation it would take to go from the most birdlike dinosaur known, to the most dinosaurlike bird we can find.

And that would at least give us an estimate that might be high, but certainly wouldn't be low.

Let's give it a try. Tell us what's on your lists.

 

[Magnetic Poles]

Helen keeps asserting that mutation only causes loss of function, despite the evidence and despite challenges to prove her assertion.

How about the fact that microbes mutate to be resistant to certain antibiotics?

An unsubstantiated claim to protect a fossilized worldview does not make it so.

 

[Helen]

The mutation of bacteria to resist antibacterial agents involves a change in the folding of the protein where the original substrate is lost.

MP, what evidence do you have that any mutation causes a new function?

One other point about your microbes. Their mutations are hot spot mutations, going back and forth. So there is always some percentage of a colony or population with resistance to antibiotics. This has to be because they cannot mutate AFTER exposure which would kill them!

Galatian, get the breast bone turned upside down, establish feathers (which have NO relation to scales!), provide wings, muscles, and the blood supply necessary for them. Add the nerve extensions and instincts necessary. Don't forget the tendons and ligaments which must attach differently. Change the bones from heavy to light.

How many mutations? How many generations would all this take?

For those who are not aware, of every thousand expressed mutations there is MAYBE one that might be beneficial. However it is beneficial because, like the antibiotic-resistant microbes, it delets function.

So go ahead, Galation, start deleting functions with beneficial mutations at the rate of a thousand to one and get from a dinosaur to a flying bird before that place below freezes over.

 

[UTEOTW]

Let's look specifically at the evolution of resistance to the antibiotic vancomycin.

Vancomycin works by attacking the D-alanyl-D-alanine in the cell wall of the bacterium. There are two genes, VanR and VanS, whose job is to make proteins to detect the presence of vancomycin. When detected, a cascade of other enzymes are created to protect the cell. VanH starts by converting precursor materials into D-lactate. VanA then joins the D-lactate with D-alanyl to make D-alanyl-D-lactate, instead of D-alanyl-D-alanine which is usually used in the cell wall. VanX hydrolyzes the D-alanyl-D-alanine that is still being made before it can be used in the cell wall.

This is the usual process, but there are variations. Some bacteria have VanB instead of VanA to make D-alanyl-D-lactate. Some bacteria replace the D-alanyl instead and make D-serine-D-alanine component instead of D-alanyl-D-lactate.

Once the resistance evolved, it was spread through plasmids.

So, why do you think that bacteria would be carrying around a gene such as VanX that hydrolyzes its own cell wall? What is the loss of function in this cascade? Which of these enzymes was produced by hotspots? Which of these is the loss due to a new folding of the protein?

"what evidence do you have that any mutation causes a new function?"

http://www.baptistboard.com/ubb/ultimatebb.php/topic/66/21.html

There are several examples. Some include...

"Selective sweep of a newly evolved sperm-specific gene in Drosophila," Nurminsky DI, Nurminskaya MV, De Aguiar D, Hartl DL, Nature. 1998 Dec 10;396(6711):572-5.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9859991&dopt=Abstract

You have two genes that are beside each other. They get duplicated. In one of the copies, some of the sequence between the two genes gets deleted. This allows the genes to combine into one chimeric gene. You have the two original genes intact and you have a new gene.


"Adaptive evolution after gene duplication," Hughes AL, Trends Genetics, 2002 Sep.18(9):433-4.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12175796&dopt=Abstract

In this case a gene, RNASE1, was duplicated such that we had a new gene, RNASE1B. These genes occur in the colobine monkey, douc langur and make pancreatic ribonuclease. Through a change in diet, the conditions within the digestive tract of the monkey were altered. Through delective pressure, the B copy of the gene mutated until it was adapted to digest single stranded bacterial RNA.

Again, we have new information. The original gene still exists to perform its original function. The gene was duplicated. When the copy mutated, then there was information that was not there previously, namely the new DNA sequence. The second copy eventually mutated until it performed a new digestive process.


"Syncytin is a captive retroviral envelope protein involved in human placental morphogenesis," Mi S, Lee X, Li X, Veldman GM, Finnerty H, Racie L, LaVallie E, Tang XY, Edouard P, Howes S, Keith JC Jr, McCoy JM, Nature 2000 Feb 17;403(6771):785-9.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=20155476&dopt=Abstract

In this case, a retrovirus inserted a section of DNA into the genome. In this case, humans have co-opted the gene to serve an important role in the area of human placental morphogenesis. The purpose of the original gene was as the envelope gene of the virus. So humans gained a gene and a function which they previously did not have. The information of the human genome was thus increased.

 

[Helen]

Suggest you start a new thread with this one, UTE. This thread is for the birds...