Just the usual tedious YEC same old same old. Say that Feduccia is insightful and right about birds not descending from theropod dinosaurs, but brainwashed and wrong about branching off a common ancestor.
1 Like
Except all the evidence I mentioned in this post, and which you have just flat out ignored.
You need to stop repeating falsehoods.
2 Likes
You must be joking. Birds with claws like this, on their wings?
Let’s not forget the long bony tail. What bird has a long bony tail like that? That’s right, none. I’m no comparative anatomist but even I can see the idea that archeopteryx isn’t a transitional form is ridiculous. It’s from the correct timeperiod, it has a mix of traits. The only rational explanation is that it’s a transitional form. An organism with that mix of traits simply has no reason to exist if evolution did not occur.
Sorry.
4 Likes
AIUI, Feduccia’s hypothesis (right side) is that birds and feathered ‘dinosaurs’ branched off the lineage that led to dinosaurs much earlier than most palaeontologists think it did (left side). So there would still be birds with claws - they’d just be archosaur claws rather than dinosaur claws.
If feathers evolved at ‘F’ on the lineage to birds, there’d be no feathered dinosaurs under Feduccia’s hypothesis, but there would be under the mainstream view.
Of course if Feduccia is correct birds still evolved from reptiles (archosaurs rather than dinosaurs), Archaeopteryx is still a transitional (between archeosaurs and birds rather than dinosaurs and birds), and @Giltil is still wrong.
7 Likes
Even excluding the obvious indicators like claws and tails, how easy is it to mistake a pair of ‘limbs’ that that are in the process of becoming wings (and thus losing their function for terrestrial movement along the way), with a pair that had already become wings and are now also losing that function as well?
I would think that in most cases there’d be fairly clear markers (though of course it’d be more difficult to tell for incomplete skeletons).
This is of considerable interest to me, as my home country (NZ) is known for its wide range of (extant and extinct) flightless birds, including ratites (kiwi and moa), parrots (kakapo) and rails (weka and takehe).
But what if Archaeopteryx was a bird?
That would depend on how long they’ve been wings and how much modification there had been. Archaeopteryx had perfectly good theropod forelimbs, not the oddly reduced and fused bones of modern birds. Also remember that theropod forelimbs hadn’t been used for locomotion since the Triassic, with the possible exception of tree-climbers.
2 Likes
Only by rather badly mutilating what the word “bird” means (Wikipedia):
Despite their small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes (“killing claw”), feathers (which also suggest warm-bloodedness), and various features of the skeleton.[5][6]
Should we also start calling the T Rex a bird? 
3 Likes
Then it lost flight but evolved claws, sharp teeth, and a long bony tail?
Then birds are all the more like dinosaurs. You can decide to categorize it however you please, but you’re not going to get around the things we can see with our own eyes. It is not like modern birds. It has some of the traits, lacks others, and have those of older fossil organisms too. It’s from the correct timeperiod. It meets every definition of a transitional fossil one could hope for.
7 Likes
Whether Archaeopteryx was a bird depends on how you choose to define the term, which is not a formal taxonomic term. But it definitely flew, as did Microraptor. The question is whether the ancestors of, for example, Caudipteryx and Deinonychus ever flew, and that’s a hard question to answer. None of that, however, prevents Archaeopteryx from being a clear transitional form. You see a lot of claims that it’s a “fully formed” bird, but that’s like calling a Model T a fully formed Tesla.
5 Likes
Yes, I had forgotten that. But still, the representations I’ve seen of theropod forelimbs don’t seem to match the wings (vestigial or otherwise) of flightless birds I’ve seen. Even distantly-lost land locomotion seems structurally very different from lost-flight.
That’s because the flightless birds you have seen are the result of a very long series of adaptations to flight, most of which Archaeopteryx and other early maniraptorans lacked. There’s really a huge difference between the wings of modern flightless or flying birds and the wings (or whatever) of the various “feathered dinosaurs”. There’s some comparison possible regarding their feathers, but not much for the skeletons.
4 Likes
Then Archaeopteryx is a transitional between archeosaurs or dinosaurs and living birds.
Using a different definition of what qualifies as a bird so that Archaeopteryx qualifies as a bird doesn’t stop Archaeopteryx being transitional. Changing what you call something doesn’t change its properties.
Incidentally, the standard definition of birds[1] does not include Archaeopteryx, since Archaeopteryx had teeth.
warm-blooded vertebrates constituting the class Aves, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. ↩︎
4 Likes
Well, it seems you can be a bird, granted an extinct bird, and have teeth. This was the case of enantiornithines.
Well, if we assume that all birds that ever lived had or have a common ancestor (an idea that I accept), how would you distinguish between Archaeopteryx being a transitional form from belonging to a separate lineage of birds?
1 Like
There really is no standard definition of “bird”. There’s not even a standard definition of “Aves”. Using these ambiguous terms doesn’t seem helpful. The important point is that what we usual think of when we say “bird”, i.e. the living species, is the product of a long evolutionary history, with different features arising at different times. Archaeopteryx has some of these features but not others, and that’s what “transitional” means.
There is no reason that it couldn’t be both. You seem to think of transitional forms as necessarily ancestral to current ones, but that is neither necessary nor discernable.
4 Likes
How would you distinguish non-avialan paraves, such as dromaeosauridae?
Etc. Etc. Following that line of argument, any dividing line between “birds” and “non-avian dinosaurs” is essentially arbitrary. They’re all “birds” in an increasingly broad, and thus vague, sense. The most logical arbitrary line would appear to be one that includes all features found in modern “birds” and excludes all features not found in them.
1 Like
They aren’t birds by the standard definition.
If you have a different definition of what ‘bird’ means, present it.
I wouldn’t. Transitional forms, like all fossils, are assumed to belong to a separate lineage from the lineage that actually led to later species for the simple reason that no matter how close they are to being an intermediate between preceding and succeeding life forms there is no way to be sure that they are direct descendants/ancestors.
So Archaeopteryx is a transitional form, and is considered to belong to a separate lineage that branched off somewhere along the line of descent from archeosaurs or dinosaurs to modern birds.
3 Likes
That “standard” definition is muddled, as Class Aves itself has many definitions, some of which include toothed birds and one of which (the crown group definition) does not. Regardless, contrary to your dictionary, “bird” and Aves are not strongly attached to each other; the former just isn’t a scientific term.
1 Like
Is there any feature that a “bird”, sufficiently broadly defined, can’t have? Quadrupedal locomotion? Gills? Lack of bony vertebrae? If we allow teeth, claws and bony tails, what’s inconsistent in allowing these other features?