#7340: — 10/21  at  06:50 AM
cf. Microraptor?

#7342: PZ Myers — 10/21  at  07:16 AM
Yes -- the paper explicitly compares the fossil to Microraptor.

#7351: Reed A. Cartwright — 10/21  at  10:17 AM
[creationist]It's just another fossil hoax like Lucy.[/creationist]

#7372: — 10/21  at  01:59 PM
[Creationist] Oh really? If current birds have 2 feathered limbs, and this fossil supposedly shows evidence for 4 feathered limbs, then why isn't there any fossil evidence for a "smooth transition" between the two species?

In other words:

Why haven't you (scientists) found any evidence of birds/dinosaurs with 3 feathered limbs?

Since you (scientists) haven't, evolution MUST be false.

#7373: — 10/21  at  02:06 PM
These fossils are known as opposite birds (Hence Enantio). They were common in the Cretaceous but died out at the KT boundry. This opposite term is supposed to be because of the way certain aspects of their skeleton fuse together in an opposite way that we see in modern birds (I do not totally buy their reasoning).

Many extant birds have feathers on their hind limbs. Also, many birds have long feathers on their hind limbs. Having long feathers on ones hind limb in no way indicates these feathers were used to provide lift, or were derived from feathers that did.

The Enantiornithine bird shown has feathers running down its leg to the top of the tarsometarsus which is the begining of its ankle. There are birds today that have feathers (rather long ones as well) running all the way down to the foot.

This animal is not closely related to the Microraptors in any way and this includes M. gui which does show well develop "flight-style" feathers on its hind limbs. The Enantiornithines have large amounts of avian traits and were well down the path of being what we would recognize as "bird". Microraptors are far more bird-like than many authors state, but resemble your standard non-avian theropod dinosaur in most aspects.

I have not had a chance to read the article in full, and once I do, I will attempt to explain their reasoning more if I find other evidence that backs their point not represented in the photo.

Some evidence has been given, in recent years, that Archaeopteryx had elongated feathers on its hind quarters, and since Archaeopteryx more closely resembles dromaeosaurs like Microraptors, than birds like Enantiornithines, the authors of the above paper may be trying to endorse this as a sign of a four-winged past in all avian tradition, or at least some well known lines. This is typical stance of geologists who have not had enough developmental biology training (Sorry, just trying to get people angry).

#7424: — 10/23  at  05:48 AM
My copy of Nature having now landed on the mat, I can reassure Lago that the authors do not suggest that the hind limb feathers here provided lift, they are extremely modest about the possibility that long hind limb feathers may be a shared primitive characteristic in various avian line, and they mention M gui only in general analogy.

So now he can take something and lie down.

#7426: — 10/23  at  08:11 AM
This reminded me of a picture I had seen recently in a book called "Extraordinary Pidgeons". One of the variety of fancy pidgeon mutants have feathers on their hind legs.

See http://www.angelfire.com/ga3/pigeongenetics/colorpigeons1.html for a picture.

amy

#7427: — 10/23  at  09:13 AM
Chris

I have read the copy as well, and everything I said still is applicable. The authors do try and state that such feathers are not know from modern birds. Seen an eagle as of late?

Next, on the M. gui bit. Microraptor was mentioned by a "Chris". I was just trying to make certain that it was generally known these are two very separate groups.

I also did not say the authors were going to imply that these feathers were used for flight. I said this:

"Many extant birds have feathers on their hind limbs. Also, many birds have long feathers on their hind limbs. Having long feathers on ones hind limb in no way indicates these feathers were used to provide lift, or were derived from feathers that did."

In other words, It is key modern feathers that resemble the feathers in question show no signs of having been derived from a lift providing feathers.

I then went on to make a guess at their hypothesis here:

"Some evidence has been given, in recent years, that Archaeopteryx had elongated feathers on its hind quarters, and since Archaeopteryx more closely resembles dromaeosaurs like Microraptors, than birds like Enantiornithines, the authors of the above paper may be trying to endorse this as a sign of a four-winged past in all avian tradition, or at least some well known lines."

Seems I was right on the money huh?

What I suggest, and did also suggest in my first post, was that long feathers on the tibiotarsus in modern birds are known, and show no signs of being a trait left over from a four-winged past, so why should these elements indicate a common ancestral pattern of four-winged flight in the Enantiornithine presented?

Comments?

#8300: — 11/04  at  05:11 PM
Fellows,
Please try to remember that being creationist does not rule out variations in evolving nor extinctive processes (except for the most fundamental among us). According to rare evidence from internal organs and diaphrams, dinosaurs were not akin to mammals,reptiles, or avians in internal functioning and body temperature maintenance.
It is probable that there is no direct link between dinosaur like birds and modern avians. They are separately developing lines. Dinosaurs and most dinosaur like birds probably did not evolve directly into modern birds. A few lines may have survived the die off to become progenitors of modern avians, but the proposed "4 wing" birds were not members of these lines (nor were the article authors suggesting that they were).

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#8353: — 11/06  at  12:00 AM
"Please try to remember that being creationist does not rule out variations in evolving nor extinctive processes (except for the most fundamental among us). According to rare evidence from internal organs and diaphragms, dinosaurs were not akin to mammals, reptiles, or avians in internal functioning and body temperature maintenance."

The diaphragm bit was a false claim by Ruben, who had a conclusion based on a picture he saw. The person actually working on the fossil explained after Ruben's comments, that what he was looking at in the photo, was actually a crack that had been fixed in the fossil. Also, the histological evidences of theropod bones is very close to what we see in modern birds, and in some cases, near identical.


There simply is NO evidence for what you said above. Yes, there are variations in dinosaur anatomy. Looking at a sauropod, and cerotopsain, and a theropod will tell you that in a glance. Variations do not preclude birds evolving from those lines that are most similar to them.

We do, however, see transitional fossils between those groups. Also, Bird anatomy changed as well. Archaeopteryx is pretty much identical to the dromaeosaur dinosaurs. Confuciusornis shares a lot of traits with Archaeopteryx, but has some important changes that point more towards what we see in modern birds. Confuciusornis shows a state that has traits like. fused caudal vertebrae that forms a pygostyle, which is rather like what we see in modern birds, but also still has gastralia, which dromaeosaurs and Archaeopteryx have, but no modern bird does.

"It is probable that there is no direct link between dinosaur like birds and modern avians. They are separately developing lines. Dinosaurs and most dinosaur like birds probably did not evolve directly into modern birds. A few lines may have survived the die off to become progenitors of modern avians, but the proposed “4 wing” birds were not members of these lines (nor were the article authors suggesting that they were)."

Of course most lines died out. Where was this in dispute? Who made claim the above Enantiornithine was a direct ancestor of modern birds? No one has even made claim that Asparavis from the late Cretaceous was actually the ancestors of modern birds (though some generalize due to its near node like characteristics)

In short, do you think Archaeopteryx is a bird? Or a Dinosaur? If it is not a bird, which is the oldest know fossil of an actual bird, in your opinion?