First birds: Archaeopteryx gets company


More birds in Jurassic:

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I’ve heard criticisms of archaeopteryx that it technically isn’t a transtional species. How do you guys respond?

That evolution doesn’t work that way? Let me try: it is not a transitional species in the sense that it led DIRECTLY from birds to dinosaurs but it is transitional in the sense that it has birdlike and dinosaur like features and we find it at a time when we would expect to see birdlike features beginning to develop in dinosaurs since birds come on the scene after this.

How did I do? More clarity would be appreciated. @T.j_Runyon, @Patrick, @swamidass, @T_aquaticus

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(T J Runyon) #3

Yep. You pretty much got it. Though I don’t see why Archy couldn’t be a direct ancestor of birds. Though it’s much more likely to be a cousin to that ancestor. Opponents of evolution like to define transitional as direct ancestry, But there’s just no way to really know this. Descendants hold onto traits of their ancestors. So we know the traits we would expect to exist existed and they did so around the time that they should have

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(T J Runyon) #4

You can never go wrong asking bird questions to a an avian phylogeneticist. @Mark @John_Harshman

(John Harshman) #5

It could be; we just have no way of telling. The tree in that area isn’t all that well resolved, and all we expect of a direct ancestor is that it should be on a very short branch from the ancestral node, ideally one of zero length. But a cousin could easily show the same.

As you mention, a transitional species doesn’t have to be an ancestor anyway.

(Robert Byers) #6

They should keep looking. They will find all bird kinds that were alive then.
What is a better flier then another flier? If you can fly you can fly. How staggering could the first one of been ?
these creatures were fossilized about 4500 years ago. Miost birds then simply would have troubkle gettimng fossilized. Its probably that these were close to the ground and caught.Maybe like Turkeys they were somewhat flightless or used wings very little. This is common today amongst birds.
Its not that there was evolution progress going on.

(Robert Byers) #7

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what about the (suppose problematic) protoavis?:

(T J Runyon) #9

Likely a chimera. Other specimens from that location have been called chimeras as well. That’s a real problem there.

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even if its a chimera some of its traits suppose to be more bird-like. isnt it interesting?

(Blogging Graduate Student) #11

Not especially. The relevant part from that wikipedia page:

The braincase is where Protoavis comes close to being as avian as Chatterjee has maintained. The otic capsule is allegedly organized in avian fashion, with three distinct foramina arranged as such: fenestra ovalis, fenestra pseudorotunda, and the caudal tympanic recess, with a bony metotic strut positioned between the fenestra pseudorotunda and caudal tympanic recess.[1][10] The claim that the full complement of tympanic recesses seen in ornithurines, are similarly observed in Protoavis is questionable, as the preservation of the braincase is not adequate to permit concrete observations on the matter. Chatterjee omits in his 1987 account of the braincase, the presence of a substantial post-temporal fenestra,[12] which in all Aves(including Archaeopteryx ), is reduced or absent altogether,[8][13] and the lack of a pneumatic sinus on the paroccipital.[13] Furthermore, the braincase possesses multiple characters symplesiomorphic of Coelurosauria, including an expanded cerebellar auricular fossa, and a vagal canal opening into the occiput.[14] What is preserved of the preorbital skull curiously lacks apomorphic characters to be expected in a specimen, which is allegedly more closely allied to Pygostylia than is Archaeopteryx lithographica . Most telling is the complete absence of accessory fenestrae in the antorbital fossa, leading to maxillary sinuses.[8]

(T J Runyon) #12

Winter has a good section on it here:


People tend to confuse ancestral with transitional. Those are two different things. A transitional fossil should have a mixture of features found in an ancestral group and a descendant group. This is exactly what Archy has, a mixture of non-avian dinosaur features and bird features. Archy is transitional.

Or as Darwin put it:

(Robert Byers) #14

Then it would be transitional features and not a transitional species. thats what i read always.
This is different .
Then who decides if a feature is transitional. FIRST it means a classification system is being presumed.
A diversity in features for any creature must be a option.
All this dino to bird stuff is about insisting birds could not have a few traits, like a tail, but must mean they are a reptile. instead it should simply be thought its a bird with a few details that it needed in a different niche.
As research gets better all these old fossils are more accurately seen as just regular birds with a few features/traits not much more radical then living birds have in a diversity.

(Matthew Pevarnik) #15

I’ll take ‘make random stuff up for $200 Alec.’

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If it has transitional features then it is a transitional species, by definition.

No one. You simply look at the features that dinosaurs have, the features birds have, and then see what features Archy has. As it turns out, Archy has a mixture of dinosaur and bird features.

Bird features: feathers, wishbone, opposable hallux, pubis elongate and directed backward

Dinosaur features: Premaxilla and maxilla are not horn-covered, Trunk region vertebra are free, Bones are pneumatic, Pubic shafts with a plate-like, and slightly angled transverse cross-section, Cerebral hemispheres elongate, slender and cerebellum is situated behind the mid-brain and doesn’t overlap it from behind or press down on it, Neck attaches to skull from the rear as in dinosaurs not from below as in modern birds, Center of cervical vertebrae have simple concave articular facets, Long bony tail with many free vertebrae up to tip (no pygostyle), Premaxilla and maxilla bones bear teeth, Ribs slender, without joints or uncinate processes and do not articulate with the sternum, Pelvic girdle and femur joint is archosaurian rather than avian (except for the backward pointing pubis as mentioned above), The Sacrum (the vertebrae developed for the attachment of pelvic girdle) occupies 6 vertebra, Metacarpals (hand) free (except 3rd metacarpal), wrist hand joint flexible, Nasal opening far forward, separated from the eye by a large preorbital fenestra (hole), Deltoid ridge of the humerus faces anteriorly as do the radial and ulnar condyles, Claws on 3 unfused digits, The fibula is equal in length to the tibia in the leg, Metatarsals (foot bones) free, Gastralia present

(Robert Byers) #17

Again your just listing traits of other creatures that are in no way birds or theropod dinos.
I mean these are not traits particular to these creatures but general traits everybody can have if they need it.
You start from a presumption there are dinosaurs. Then you look at features. Thats the first error. one should just look at features to prove it there is a justification to say there is a dino group.
so if “theropod idinos” have a few likle traits with non theropod creatures YOU are concluding they are related. This is just guessing.
the thing to compare is the great number of traits, in a sum, to draw connections between relationships of descent.
that is why the error includes the whole concept of there being reptiles or mammals. Thyese groups are myths. Its just a coincidence they have some like traits. In limited options in biology.
The clear evidence is that theropod dinos are so much like birds that THEY INVENT the idea birds come from theropods. some call birds dinosaurs/reptiles.
Yet its the other way around. theropod dinos are just boring ground birds. However big and teethy.
Accurate investigation should start with comparing, and summing, traits. NOT start with presumptions of common descent. This is poor science otherwise.
Its all a error of 19th century upper class Englishmen in small circles.



Then perhaps you can take a picture of humans with feathers, or humans whose vertebrae attach to the back of the skull?

When those shared and derived traits fall into a nested hierarchy I do conclude that they are the result of evolution and shared ancestry because that is the pattern those mechanisms produce. It is the PATTERN of shared and derived features that points to evolution, something that you continually misunderstand.

Just like bears are boring ground bats. Yeah.

(Jonathan) #19

Greetings, @Robert_Byers!

There are actually a lot of key differences between birds and dinosaurs. One that I find particularly interesting is that, while birds are warm-blooded, many scientists think that dinosaurs were cold blooded (or something in between warm-blooded and cold-blooded like leatherback turtles). That is a pretty big difference :wink: .

Also, you might be interested in this Answers in Genesis article entitled “Birds are Not Dinosaurs!” I’m sure you would agree that AiG does not start with presumptions of common descent.

(John Harshman) #20

No they don’t. Dinosaurs are not a monolithic group. The dinosaurs most closely related to birds show evidence of being as warm-blooded as birds. Why else have feathers covering their bodies?

He probably would be, since it fits his preconceptions and his intellectual level. Anyone else would find it nonsensical. AiG is not a credible source for biology. (Or anything else, really.)