Study find 100's of possible alternative evolutionary paths

The accumulation of small heritable changes within populations over time.

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Re: Study find 100's of possible alternative evolutionary paths

#81  Postby Zadocfish2 » Sep 26, 2017 6:59 pm

Calilasseia wrote:Funnily enough, there's a Tanita Tikaram song called Poor Cow. :)

But the fun part is, the whole "I've never seen a dog give birth to a cat" tripe that is stock creationist fare, not only demonstrates ignorance of several key points of evolutionary theory, but would fail even to constitute a valid observation, under one possible evolutionary scenario. That scenario consisting of [1] cats as currently constituted all becoming extinct for some reason, [2] a wild dog species moving into the same niche, and [3] over many generations, acquiring cat-like features via convergent evolution, leading to future radiation of organisms superficially resembling the previously extant, but now extinct, true cats. To the untrained eye, the resulting animals would end up resembling cats in appearance, to the point where anatomically naive individuals, familiar with extinct cats, would probably start labelling them 'cats'. Except that they would, in fact, be dogs, courtesy of their ancestry.

And for those who think that this scenario is ridiculously implausible, scenarios of a similar sort have actually occurred in the past. Artiodactyl mammals are, in the present, represented by primarily herbivorous species, such as sheep, cattle, deer, hippos, and pigs. However, one group of Artiodactyls in the past, the Entelodonts, were carnivorous mammals, colloquially referred to as "Terminator Pigs", courtesy of the fact that their morphology initially suggested a relationship with the Suidae. The largest of these, Daeodon, a North American species, was 6 feet high at the shoulder and close to 900 pounds in weight. What we have in these animals, is organisms originating from a pig like ancestor, that moved into the niche occupied in the present by hyaenas, though taxa such as Daeodon grew to be far larger than any present day hyaena.


Yep, convergent evolution is absolutely a thing. Apparently dinosaurs were experimenting with the "bat" archtype while pterosaurs were still around, and flying squirrels/sugar gliders are kinda re-treading the same ground right now. Then there's tree sloths, dolphins/ichthyosaurs, seals/whale ancestors, and many more. Some body types and survival strategies just... work.
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Re: Study find 100's of possible alternative evolutionary paths

#82  Postby theropod » Sep 26, 2017 8:11 pm

Oh for fucks sake. Dinosaurs and pterosaurs were distinctly different in many ways. There were no "experiments" as asserted. Read a fucking book.

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Re: Study find 100's of possible alternative evolutionary paths

#83  Postby Zadocfish2 » Sep 27, 2017 7:02 am

... I was talking about this: https://en.wikipedia.org/wiki/Yi_(dinosaur) It's a dinosaur that seemed to be following a similar trajectory to bats and, to a lesser extent, pterosaurs.

I meant that dinosaurs were "experimenting" with membranous flight even while pterosaurs were still around, meaning membranous flight evolved independently in earlier archosaurs, in dinosaurs, AND in mammals, and I find that fascinating.
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Re: Study find 100's of possible alternative evolutionary paths

#84  Postby DavidMcC » Sep 27, 2017 3:52 pm

theropod wrote:Oh for fucks sake. Dinosaurs and pterosaurs were distinctly different in many ways. There were no "experiments" as asserted. Read a fucking book.

RS

Of course they were, but that doesn't mean there wasn't convergent evolution of some aspect or other.
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Re: Study find 100's of possible alternative evolutionary paths

#85  Postby theropod » Sep 27, 2017 4:04 pm

Zadocfish2 wrote:... I was talking about this: https://en.wikipedia.org/wiki/Yi_(dinosaur) It's a dinosaur that seemed to be following a similar trajectory to bats and, to a lesser extent, pterosaurs.

I meant that dinosaurs were "experimenting" with membranous flight even while pterosaurs were still around, meaning membranous flight evolved independently in earlier archosaurs, in dinosaurs, AND in mammals, and I find that fascinating.


Your link directs one to an empty Wiki page. HERE is the correct Wiki reference. It seems you left off a closing parentheses.

From the Wiki entry..
...make it more likely that Yi qi was an exclusive glider. At best, the researchers who conducted the initial study of the only known Yi specimen concluded that its mode of flight should be considered uncertain.


It's hard to tie convergence to this maniraptoran theropod with pterosaurs when there isn't enough known to definitively ascribe a mode of flight. As far as I understand the subject pterosaurs all were powered fliers. If Yi qi was an exclusive glider the convergence argument falls down.

Let's look at an informed examination of this dinosaur.

Scientific American review by Darren Nash, which I dare say knows a thing or two about the subject. Pay particular attention to the fact that some extant birds also have this sort of "skin flap".

Darren Nash wrote:So, Yi qi is a small theropod with patagia. Radical, right? Well, not so fast. What’s been mostly overlooked in discussions of Yi qi is that pennaraptoran maniraptorans already have patagia. Look at the (perhaps familiar) pictures of nightjar wings below and observe all the ‘webbing’ that surrounds the fingers and arm. A membrane called the propatagium spans the space between the wrist and shoulder, and membranes run along the trailing (or posterior, or postaxial) edges of the hand and ulna too.


Then let's read the actual peer reviewed publication (full PDF) found in the journal Nature Letters.

(doi:10.1038/nature14423).

"A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings"

Xing Xu, Xiaoting Zheng, Corwin Sullivan, Xiaoli Wang, Lida Xing, Yan Wang, Xiaomei Zhang, Jingmai K. O’Connor, Fucheng Zhang & Yanhong Pan

Note the closing statement from the authors quoted below, with bold emphasis added by me.

There are some indications that Yi may have relied more on gliding than on flapping, including the lack of strongly expanded muscle attachment surfaces on the forelimb bones and the possibility that the unwieldy styliform element would have interfered with the rapid oscillations and rotations of the distal part of the forelimb needed for efficient flapping flight, but the mode of aerial locomotion that is most likely for Yi remains uncertain. Regardless, the evident occurrence in this taxon of a membranous wing supported by a styliform element represents an unexpected aerodynamic innovation close to the origin of birds, and highlights the breadth of flight-related morphological experimentation that took place in the early stages of paravian history.


No part of this dinosaur adaptation followed the pterosaur model. Merely having a "wing flap" of skin does not indicate an "experiment" along the same evolutionary pathway as pterosaurs, as extant birds, as noted by Nash, also have this morphological feature. Powered flapping flight, as is found in pterosaurs, and gliding, as is suggested by the actual researchers, is not a case of convergence. My issue revolves around the notion that convergent evolution follows any other example by temporally extant organisms. It is this sort of conjecture which confuses the lay person into thinking that pterosaurs were dinosaurs. I actually addressed this on this very forum (Science Writing Competition), and expressed my deep concerns with the confusion such comparisons instill. Lay people often conflate these distinctively differing families already, and attempting to tie convergence between pterosaurs and dinosaurs only further deepens such misunderstandings. Yes, evolution was allowing for the approach to the problem of flight in a somewhat convergent manner, but not by following any other example. If we go down that road we are forced to accept that insect flight, which predates all other forms of flight, as an example of a pattern to which all other examples follow. Yi qi developed this morphological adaptation from the maniraptoran base from which it arose, which was experiencing a wide array of divergent experiments completely apart from those taken by pterosaurs, and was proceeded by other maniraptorans already well on their way to flight.

Sorry if my knee jerk reaction is pedantic, but to a student of dinosaur paleontology such issues matter. To me true convergence would be something like the horns on Triceratops, and those found in bovines, as both served the same function, and are expressed in the same manner. Yi qi does not follow this pattern as petrosaurs developed powered flight and Yi qi was most likely a glider. Only the ability to get off the ground is similar, and the similarities ends there.

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Re: Study find 100's of possible alternative evolutionary paths

#86  Postby Zadocfish2 » Sep 27, 2017 6:19 pm

Eh... I don't think you get the point I was making. I wasn't saying it was a pterosaur, or even LIKE a pterosaur. I get that it couldn't actually fly, and that's entirely beside the point. I guarantee you, pterosaurs did not come out of thin air, so to speak, nor did bats, unless you're a YEC. Gliding generally comes before flying, as the former is far easier. Here is a dinosaur that could glide using skin flaps, just as the ancestors of both bats and pterosaurs must have during their ancient developmental history. And this wasn't a marginal ability, either; it had a specialized bone structure JUST for spreading its membrane for gliding.

It doesn't have to be the "full suite" to be a case of convergent evolution. This thing wasn't a flier, but neither were pterosaur ancestors or bat ancestors, until they were. Yi hadn't reached the point of flight yet, but it was following the same line of adaption that could eventually end in flight, as it did in bats.

I just think that's interesting, seeing as other dinosaurs developed first gliding and then flight in a completely different manner (flight feathers).
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Re: Study find 100's of possible alternative evolutionary paths

#87  Postby theropod » Sep 27, 2017 8:08 pm

OK, apparently I did not understand what you were saying. Nevermind then, Zadocfish2.

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Re: Study find 100's of possible alternative evolutionary paths

#88  Postby DavidMcC » Sep 30, 2017 2:56 pm

DavidMcC wrote:
theropod wrote:Oh for fucks sake. Dinosaurs and pterosaurs were distinctly different in many ways. There were no "experiments" as asserted. Read a fucking book.

RS

Of course they were, but that doesn't mean there wasn't convergent evolution of some aspect or other.

Ie, not the whole organiam. Convergence does not have to mean complete convergence.
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Re: Study find 100's of possible alternative evolutionary paths

#89  Postby theropod » Sep 30, 2017 4:52 pm

DavidMcC wrote:
DavidMcC wrote:
theropod wrote:Oh for fucks sake. Dinosaurs and pterosaurs were distinctly different in many ways. There were no "experiments" as asserted. Read a fucking book.

RS

Of course they were, but that doesn't mean there wasn't convergent evolution of some aspect or other.

Ie, not the whole organiam. Convergence does not have to mean complete convergence.


Did you even bother to read the post directly above yours? I made a retraction. Not good enough for you?

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Re: Study find 100's of possible alternative evolutionary paths

#90  Postby DavidMcC » Sep 30, 2017 5:49 pm

Indidn't regard that as a full retraction, and the issue anyhow needed greater clarity, IMO.
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Re: Study find 100's of possible alternative evolutionary paths

#91  Postby theropod » Sep 30, 2017 6:09 pm

DavidMcC wrote:Indidn't regard that as a full retraction, and the issue anyhow needed greater clarity, IMO.


Well, sorry it didn't measure up to your standards. I will make sure to check with you beforehand next time.

:coffee:

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Re: Study find 100's of possible alternative evolutionary paths

#92  Postby DavidMcC » Oct 01, 2017 1:24 pm

theropod wrote:
DavidMcC wrote:Indidn't regard that as a full retraction, and the issue anyhow needed greater clarity, IMO.


Well, sorry it didn't measure up to your standards. I will make sure to check with you beforehand next time.

:coffee:

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:roll:
Let's just forget this happened, as you don't seem to like criticism.
EDIT: The problem with your response to criticsm is that it tends to lose sight of the thread topic, and convert it into a personality clash, like witb hackenslash (when he was here) and one or two others.
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Re: Study find 100's of possible alternative evolutionary paths

#93  Postby theropod » Oct 01, 2017 3:03 pm

DavidMcC wrote:
theropod wrote:
DavidMcC wrote:Indidn't regard that as a full retraction, and the issue anyhow needed greater clarity, IMO.


Well, sorry it didn't measure up to your standards. I will make sure to check with you beforehand next time.

:coffee:

RS

:roll:
Let's just forget this happened, as you don't seem to like criticism.
EDIT: The problem with your response to criticsm is that it tends to lose sight of the thread topic, and convert it into a personality clash, like witb hackenslash (when he was here) and one or two others.


Oh for fucks sake. My retraction didn't suit YOU, and now it's my problem? Good fucking grief. I have no problem whatsoever with criticism when there is justification for it. YOU don't have any such justification. What puts a burr under my saddle is that YOU made a wholly unwarranted judgement based on some set of abstract, and completely arbitrary, standards I failed to meet. YOU brought up the subject and now I am expected to just forget about it and let YOU slide for attempting, and failing on a grand scale, to make me look like the bad guy here. To further compound YOUR trite comments YOU make comparisons to a member no longer active and unable to defend himself, and is still protected by the FUA to the best of my knowledge. Even mentioning Hacks name is a glaring example of off topic distraction for which I feel you should be sanctioned, but that's just me. I suggest you take a long hard look in the mirror, and think twice before issuing YOUR edicts of acceptable posting style. Frankly the weak attempt to additionally lay the blame at my feet by claiming that any defense I might mount to YOUR unfounded bullshit is taking the thread off topic is laughable, and disgusting. Yeah, let's just forget that it was YOU that took the thread off topic by passing an unfounded judgement on a clear retraction, and hold hands around a campfire and become besties. Fuck that. I was wrong about the intent of a post and admitted it. Perhaps I should have offered Zacdocfish2 a sexual favor as recompense for my mortal sin of misunderstanding his position. Somehow I suspect no matter how I worded my retraction it would have failed to meet your lofty sense of ethical behavior.

Only the FUA stops me from expressing EXACTLY how I feel about your bullshit comments. Report my post(s) if you don't fucking like what I have to say, or how I say it. Short of moderator intervention one can bank on a vigorous defense mounted in response to arbitrary, and hypocritical, attacks on my comments.

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Re: Study find 100's of possible alternative evolutionary paths

#94  Postby DavidMcC » Oct 01, 2017 3:34 pm

You really DON'T like criticism, do you?
There! Now, you've made the thread all about you. Alternative evolutionary paths is out the window. I hope you like it.
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Re: Study find 100's of possible alternative evolutionary paths

#95  Postby theropod » Oct 01, 2017 4:32 pm

DavidMcC wrote:You really DON'T like criticism, do you?
There! Now, you've made the thread all about you. Alternative evolutionary paths is out the window. I hope you like it.


:whine:

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Re: Study find 100's of possible alternative evolutionary paths

#96  Postby Rumraket » Oct 01, 2017 4:46 pm

DavidMcC wrote: The problem with your response to criticsm is that it tends to lose sight of the thread topic, and convert it into a personality clash, like witb hackenslash (when he was here) and one or two others.

Am I truly reading these words coming from you?

Have I finally lost my fucking mind, or are YOU of all people really posting this?

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Re: Study find 100's of possible alternative evolutionary paths

#97  Postby Thomas Eshuis » Oct 01, 2017 5:53 pm

DavidMcC wrote:You really DON'T like criticism, do you?
There! Now, you've made the thread all about you. Alternative evolutionary paths is out the window. I hope you like it.

Actually, you derailed the thread by injecting yourself in a situation involving two other members.
"Respect for personal beliefs = "I am going to tell you all what I think of YOU, but don't dare retort and tell what you think of ME because...it's my personal belief". Hmm. A bully's charter and no mistake."
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Re: Study find 100's of possible alternative evolutionary paths

#98  Postby Zadocfish2 » Oct 02, 2017 8:30 am

This thread went in kind of a weird direction since I last checked it...

Weren't we talking about evolutionary paths? (also it's cool how apparently proteins change and adapt with time in a way similar to DNA but, presumably, using different mechanics)
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Re: Study find 100's of possible alternative evolutionary paths

#99  Postby Greyman » Oct 02, 2017 9:08 am

Zadocfish2 wrote:This thread went in kind of a weird direction since I last checked it...

Weren't we talking about evolutionary paths? (also it's cool how apparently proteins change and adapt with time in a way similar to DNA but, presumably, using different mechanics)
Uh... They are not independent. The DNA contains genes that encode production of protein molecules

DNA sites transcribe mRNA strands, which travel from the nucleus through the cytoplasm to ribosome organelles where translation of the triplet code instructs rRNA and tRNA construct a polypeptide.
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Re: Study find 100's of possible alternative evolutionary paths

#100  Postby theropod » Oct 02, 2017 12:31 pm

Greyman wrote:
Zadocfish2 wrote:This thread went in kind of a weird direction since I last checked it...

Weren't we talking about evolutionary paths? (also it's cool how apparently proteins change and adapt with time in a way similar to DNA but, presumably, using different mechanics)
Uh... They are not independent. The DNA contains genes that encode production of protein molecules

DNA sites transcribe mRNA strands, which travel from the nucleus through the cytoplasm to ribosome organelles where translation of the triplet code instructs rRNA and tRNA construct a polypeptide.


Which is indictative of that in the end all of us oxygen dependent organisms are convergent in our biochemistry. Then the issue becomes at what point does the term convergent hold value? To me, and probably many others, this question is THE question. By studying the issue we are able to find shared markers in the genomes of all life as we know it. These markers are consistent. This, in turn, allows us to look real close at the differences in the genome of different forms of life as we know it. From this we can see where divergence happens, and these divergence markers allows us to formulate a sort of genetic cladistics to ID genomes with species level precision. Beyond this we are becoming able to ID individuals of a population of species. Form my paleo centric viewpoint the study of genetic markers still extant in the genome across deep time is facilitating and enabling the capability to see evolution in ways unimaginable 30 years ago.

This tends to influence my prejudice towards looking at the differences instead of the similarities. One wonders if the differences, when examined genetically, between the convergent adaptation toward a wing flap in a maniraptoran theropod, and a basal pterosaur, were similar. The odds of getting that data to examine are approaching zero. I can imagine a vastly different set of genes, and the protiens they expressed, were responsible for giving rise to the skin flap emergence in both the basal pterosaur and the (m.) theropod. So, in my version of reality, it's a case of divergence, and convergence, at the same time.

(Criticism welcomed)

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