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Natural Environment How Human History has been impacted by the environment, science, nature, geography, weather, and natural phenomena


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Old August 18th, 2017, 08:01 AM   #31
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But... Because this can run and run.

Here we have Xiaotingia, hailed as the new urvögel a few years back. Also described as a basal dromaeosaur after having being a troodontid for a short time, but may still be a troodontid depending on which cladogram you look at, or want to believe. But whether it is a troodontid, basal dromaeosaur, avialan or even a Romulan, it comes after Aurornis, which may or may not actually be Anchiornis, work still progresses on this.

So, while we may never know who basal paraves was, I'll reiterate my previous statement that the so far, and to my knowledge, earliest known, within paraves, bird ancestor, is Aurornis, while it is still it's own species and not Anchiornis, and no matter what, birds start with basal troodonts, which is of course contentious. And I still go with Austinornis lentus as the first, so far known, modern bird.

The OP's research has concluded that the first bird is ?
My candidate is Iberomesornis, which in my humble opinion is the earliest creature which manifests practically all clear avian characteristics...The problem is, however, that the only known specimen of Iberomesornis lacks its cranium, and thus we do not know if this animal had a true beak...although this seems extremely likely. Slightly later than Iberomesornis is Confuciusornis, which was definitely beaked, although rather more archaic in anatomical structure than Iberomesornis.

The controversy continues...
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Old August 18th, 2017, 09:10 AM   #32

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Old August 18th, 2017, 09:52 AM   #33

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My candidate is Iberomesornis, which in my humble opinion is the earliest creature which manifests practically all clear avian characteristics...The problem is, however, that the only known specimen of Iberomesornis lacks its cranium, and thus we do not know if this animal had a true beak...although this seems extremely likely. Slightly later than Iberomesornis is Confuciusornis, which was definitely beaked, although rather more archaic in anatomical structure than Iberomesornis.

The controversy continues...
Though as it is included within enantiornithes, it puts into an evolutionary dead end as they are a branch that did not lead to modern birds and died out. It would need to be basal to both enantiornithes and euornithes to be a contender.

However, if any member of enantiornithes had survived to the present day, and they would have further evolved just as modern birds, we would, I am sure, class them as birds, what else could we class them as.

It is really easy to get too complicated I know, but I'll throw this point out. By the K-Pg event there were multiple lines of birds. But only one line, and just a small part of that line survived, so we see them as the "true" birds and forget the many that died out who were no less birds than those that survived, even if some had teeth. I don't see teeth as a retrograde or primitive condition, and while penguins manage fine without teeth, I wonder if there were no K-Pg that they would ever have evolved with Hesperornis still alive, with teeth better able to grip slippery fish and squid. I think modern birds manage without teeth because they have no choice, not because it is the best solution for them. The toothed birds died out, so the beaked birds had to fill the gaps as best they could.

So, are we looking for the earliest progenitor of any bird line living at K-Pg, so putting enantiornithes, and therefore Iberomesornis, back into the running, or just the progenitor of the birds that survived to this day, which I admit skews the overall picture by excluding perfectly good, but extinct birds.
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Old August 19th, 2017, 01:02 AM   #34
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Though as it is included within enantiornithes, it puts into an evolutionary dead end as they are a branch that did not lead to modern birds and died out. It would need to be basal to both enantiornithes and euornithes to be a contender.

However, if any member of enantiornithes had survived to the present day, and they would have further evolved just as modern birds, we would, I am sure, class them as birds, what else could we class them as.

It is really easy to get too complicated I know, but I'll throw this point out. By the K-Pg event there were multiple lines of birds. But only one line, and just a small part of that line survived, so we see them as the "true" birds and forget the many that died out who were no less birds than those that survived, even if some had teeth. I don't see teeth as a retrograde or primitive condition, and while penguins manage fine without teeth, I wonder if there were no K-Pg that they would ever have evolved with Hesperornis still alive, with teeth better able to grip slippery fish and squid. I think modern birds manage without teeth because they have no choice, not because it is the best solution for them. The toothed birds died out, so the beaked birds had to fill the gaps as best they could.

So, are we looking for the earliest progenitor of any bird line living at K-Pg, so putting enantiornithes, and therefore Iberomesornis, back into the running, or just the progenitor of the birds that survived to this day, which I admit skews the overall picture by excluding perfectly good, but extinct birds.
As always, Corvidius, you make excellent points and comments concerning the origin of birds. I like and appreciate your panoramic viewpoint which takes numerous diverse factors into careful consideration.

As for enantiornithes, I believe that there can be no doubt as to their evident avian nature; they may not have led directly to modern birds, yet were certainly close cousins, and in their day were highly advanced avians. It is strange that these versatile, seemingly adaptible creatures did not survive into recent times.

Internet articles can be very vague; about 2 years ago I read a brief online report concerning the supposed discovery of the skeletal remains of a juvenile Iberomesornis, complete with cranium and beak. However, after considerable searching online for more details, I finally gave up in despair...That news item seems to be unique and isolated, never followed up. Do you have any info about this purported discovery?
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Old August 19th, 2017, 01:07 AM   #35
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"What came first, the chicken or the egg? First I egged the chicken, and then I ate his leg." Beastie Boys Egg Man

Welcome back, David! I missed your posts.

Actually, the answer to "Which came first, the chicken or the egg?" is simple. First there was a chicken-like bird, which laid an egg containing genes that resulted in a mutation, a new evolved creature different from its parents: when this egg hatched, the first true chicken emerged.
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Old August 19th, 2017, 01:35 AM   #36

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The problem with the "first bird" hypothesis is that animals don't simply evolve from species A to species B in one step. If A is a bird-like dinosaur and B is a dinosaur-like bird then there will be wide range of strains in between both. Those strains can breed either way and maybe both ways. Think of evolution as something more branching and fluid rather than linear and discrete. There is a spectrum where you can't really decide whether this is a bird or a dinosaur.
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Old August 19th, 2017, 01:45 AM   #37

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As always, Corvidius, you make excellent points and comments concerning the origin of birds. I like and appreciate your panoramic viewpoint which takes numerous diverse factors into careful consideration.

As for enantiornithes, I believe that there can be no doubt as to their evident avian nature; they may not have led directly to modern birds, yet were certainly close cousins, and in their day were highly advanced avians. It is strange that these versatile, seemingly adaptible creatures did not survive into recent times.

Internet articles can be very vague; about 2 years ago I read a brief online report concerning the supposed discovery of the skeletal remains of a juvenile Iberomesornis, complete with cranium and beak. However, after considerable searching online for more details, I finally gave up in despair...That news item seems to be unique and isolated, never followed up. Do you have any info about this purported discovery?
Thanks for the comments, appreciated as I am a long long long way off being even remotely expert. I do study corvids, though while it is always dubious to apply their behaviour to long extinct birds, it does give some pointers to potential behaviours I think.

I don't keep right up to date on every paper that is published, it's not my job anyway, so couldn't give an answer on the current status of the potential juvenile Iberomesornis. However, in the latest edition of Chatterjee's work, from 2015, he includes a side on illustration of it's skeleton, which includes it's skull. As there is also an illustration of Sinornis, which there is a skull for, and the Iberomesornis is given a different skull, It could be presumed that Chatterjee is basing the reconstruction on a real example, the one you mention. In the illustration, the morphology of the rear of Iberomesornis's skull is shown as very distinct from that of Sinornis, with the orbit very rounded and the roof of the cranium higher. Would he have just made these differences up, like the skull of Dakotaraptor is made up in all it's reconstructions, I don't know.
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Old August 19th, 2017, 01:46 AM   #38
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The problem with the "first bird" hypothesis is that animals don't simply evolve from species A to species B in one step. If A is a bird-like dinosaur and B is a dinosaur-like bird then there will be wide range of strains in between both. Those strains can breed either way and maybe both ways. Think of evolution as something more branching and fluid rather than linear and discrete. There is a spectrum where you can't really decide whether this is a bird or a dinosaur.
Evolution works in strange ways. It can be (and usually is) fluid and branching, just as you have indicated. But when we are speaking of MUTATION, it can be brusque, linear, immediate.

In palaeontology, there are indeed numerous borderline cases in which it may seem quite difficult to precisely classify a creature. Oligokyphus, the almost-mammal, is one example. There are also many cases of near-birds which seem on the very verge of becoming true avians. Yet a careful anatomical and physiological examination should be able to reveal if the creature has already crossed over the line or if it remains a dinosaur in spite of its highly derived aspect.
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Old August 19th, 2017, 01:55 AM   #39

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The problem with the "first bird" hypothesis is that animals don't simply evolve from species A to species B in one step. If A is a bird-like dinosaur and B is a dinosaur-like bird then there will be wide range of strains in between both. Those strains can breed either way and maybe both ways. Think of evolution as something more branching and fluid rather than linear and discrete. There is a spectrum where you can't really decide whether this is a bird or a dinosaur.
Of course, and the problem, probably for ever unsolvable, is that the spectrum is potentially vast. While the number of all species of dinosaurs is around the thousand mark at the moment, just maniraptors, from whoever was the first one up to K-Pg, would surely have numbered tens of thousands of species, at a minimum, and so many of them little feathery things running about all looking the same.
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Old August 19th, 2017, 06:12 AM   #40
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Of course, and the problem, probably for ever unsolvable, is that the spectrum is potentially vast. While the number of all species of dinosaurs is around the thousand mark at the moment, just maniraptors, from whoever was the first one up to K-Pg, would surely have numbered tens of thousands of species, at a minimum, and so many of them little feathery things running about all looking the same.
Especially the feathered dinosaurs from China...A great number of them have been discovered in the last 2 decades; it's hard to keep track of recent finds.

Many of them may have been sub-species rather than species.
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