Originally posted by lee_merrill
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The lungfish genome, tetrapods, and junk DNA
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Originally posted by HMS_Beagle View Post
What would a not actual intermediate look like Lee? Your incompetent blithering gets worse every passing day.
Blessings,
Lee
"What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)
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Originally posted by shunyadragon View PostYes, "Tiktaalik is clearly a transitional form, but this does not necessarily translate to an actual intermediate, which is a maybe.
Blessings,
Lee
"What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)
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Originally posted by lee_merrill View PostWell, not transitional in the sense that Nature meant it, but I agree that its placement is up in the air.
Blessings,
Lee
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by lee_merrill View Post
So the difference appears to be about 22 million years.
Originally posted by lee_merrill View PostNo, the statement is simply that Tiktaalik is not a direct transitional form. That is why I quoted it, that is what they meant, Nature was incorrect in this assertion. That is not to say that there are major problems with evolutionary theory.
Beyond all that, i fail to see the point of the blog post or its relevance to this discussion. It's clear that the author of the blog post doesn't understand terminology, and is accusing biologists of being deceptive because they're not following what he thinks the definition is. And then accusing the biologists who try to explain the real one of making excuses. Like everything else on the site, it's garbage. Do not use it in my threads again.
In the larger picture, even if we deleted all knowledge of Tiktaalik somehow, we'd still have enough other fossils to clearly indicate tetrapods evolved from lobe-finned fishes. And now the DNA evidence lines up with that as well. That's the big picture, and anything else said here is just a distraction from that.
Oh yes, and i hope whenever you bring up junk DNA in the future, you manage to keep this data in mind."Any sufficiently advanced stupidity is indistinguishable from trolling."
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Originally posted by lee_merrill View PostWell, not transitional in the sense that Nature meant it, but I agree that its placement is up in the air.
Blessings,
LeeGlendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
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This seems pertinent
The abstract for the paper Functional adaptive landscapes predict terrestrial capacity at the origin of limbs is below
Abstract
The acquisition of terrestrial, limb-based locomotion during tetrapod evolution has remained a subject of debate for more than a century1,2. Our current understanding of the locomotor transition from water to land is largely based on a few exemplar fossils such as Tiktaalik3, Acanthostega4, Ichthyostega5 and Pederpes6. However, isolated bony elements may reveal hidden functional diversity, providing a more comprehensive evolutionary perspective7. Here we analyse 40 three-dimensionally preserved humeri from extinct tetrapodomorphs that span the fin-to-limb transition and use functionally informed ecological adaptive landscapes8,9,10 to reconstruct the evolution of terrestrial locomotion. We show that evolutionary changes in the shape of the humerus are driven by ecology and phylogeny and are associated with functional trade-offs related to locomotor performance. Two divergent adaptive landscapes are recovered for aquatic fishes and terrestrial crown tetrapods, each of which is defined by a different combination of functional specializations. Humeri of stem tetrapods share a unique suite of functional adaptations, but do not conform to their own predicted adaptive peak. Instead, humeri of stem tetrapods fall at the base of the crown tetrapod landscape, indicating that the capacity for terrestrial locomotion occurred with the origin of limbs. Our results suggest that stem tetrapods may have used transitional gaits5,11 during the initial stages of land exploration, stabilized by the opposing selective pressures of their amphibious habits. Effective limb-based locomotion did not arise until loss of the ancestral ‘L-shaped’ humerus in the crown group, setting the stage for the diversification of terrestrial tetrapods and the establishment of modern ecological niches12,13.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by rogue06 View PostThis seems pertinent
The abstract for the paper Functional adaptive landscapes predict terrestrial capacity at the origin of limbs is below
Abstract
The acquisition of terrestrial, limb-based locomotion during tetrapod evolution has remained a subject of debate for more than a century1,2. Our current understanding of the locomotor transition from water to land is largely based on a few exemplar fossils such as Tiktaalik3, Acanthostega4, Ichthyostega5 and Pederpes6. However, isolated bony elements may reveal hidden functional diversity, providing a more comprehensive evolutionary perspective7. Here we analyse 40 three-dimensionally preserved humeri from extinct tetrapodomorphs that span the fin-to-limb transition and use functionally informed ecological adaptive landscapes8,9,10 to reconstruct the evolution of terrestrial locomotion. We show that evolutionary changes in the shape of the humerus are driven by ecology and phylogeny and are associated with functional trade-offs related to locomotor performance. Two divergent adaptive landscapes are recovered for aquatic fishes and terrestrial crown tetrapods, each of which is defined by a different combination of functional specializations. Humeri of stem tetrapods share a unique suite of functional adaptations, but do not conform to their own predicted adaptive peak. Instead, humeri of stem tetrapods fall at the base of the crown tetrapod landscape, indicating that the capacity for terrestrial locomotion occurred with the origin of limbs. Our results suggest that stem tetrapods may have used transitional gaits5,11 during the initial stages of land exploration, stabilized by the opposing selective pressures of their amphibious habits. Effective limb-based locomotion did not arise until loss of the ancestral ‘L-shaped’ humerus in the crown group, setting the stage for the diversification of terrestrial tetrapods and the establishment of modern ecological niches12,13.
Left out the link and abstract for the more recent paper, Evolution of forelimb musculoskeletal function across the fish-to-tetrapod transition, which can be read in its entirety at the provided hyperlink. Here is the abstract
Abstract
One of the most intriguing questions in vertebrate evolution is how tetrapods gained the ability to walk on land. Although many hypotheses have been proposed, few have been rigorously tested using the fossil record. Here, we build three-dimensional musculoskeletal models of the pectoral appendage in Eusthenopteron, Acanthostega, and Pederpes and quantitatively examine changes in forelimb function across the fin-to-limb transition. Through comparison with extant fishes and tetrapods, we show that early tetrapods share a suite of characters including restricted mobility in humerus long-axis rotation, increased muscular leverage for humeral retraction, but not depression/adduction, and increased mobility in elbow flexion-extension. We infer that the earliest steps in tetrapod forelimb evolution were related to limb-substrate interactions, whereas specializations for weight support appeared later. Together, these results suggest that competing selective pressures for aquatic and terrestrial environments produced a unique, ancestral “early tetrapod” forelimb locomotor mode unlike that of any extant animal.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by TheLurch View PostBeyond all that, i fail to see the point of the blog post or its relevance to this discussion. It's clear that the author of the blog post doesn't understand terminology, and is accusing biologists of being deceptive because they're not following what he thinks the definition is.
In the larger picture, even if we deleted all knowledge of Tiktaalik somehow, we'd still have enough other fossils to clearly indicate tetrapods evolved from lobe-finned fishes. And now the DNA evidence lines up with that as well.
Blessings,
Lee"What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)
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Originally posted by lee_merrill View PostActually, the author says biologists have two different definitions of a transitional form, a hard definition (an actual intermediate), and a soft definition (a morphological intermediate, which may not be an actual intermediate). He then takes biologists to task for switching definitions when it turns out that Tiktaalik may not be an actual intermediate, without acknowledging that the definition has been switched.
If you had simply done as I asked and gone to any reputable site you'd find that there is no such thing as a "hard definition" and "soft definition" in biology. That is utter bilge.
While there is popular usage of the term it is not the same one scientists use (as is often the case - see "Theory" for instance). Your garbage site sleazily implies that this first way is one of the accepted ways that scientists use it in an attempt to deceive or bamboozle. But that is exactly what they are doing here.
It is not[1]
In biology it refers to any organism that displays characteristics that are commonly found in both an ancestral group and its derived descendant group. It does not have to be the progenitor of the descendant group itself, it just needs to display the traits found in both groups. As I said in post #27
It doesn't have to be a direct ancestor. It could even be an evolutionary dead end.
A transitional form serves to illustrate an evolutionary link, in that it can have features of two separate groups of species, but have no other species as descendants. Therefore, a transitional form merely needs to record aspects of evolutionary change that occurred as one lineage split from another. It does not need to be the direct descendant of one species and the direct ancestor of another, and is a mistake to assume otherwise.
As the noted paleontologist Donald Prothero (one of my favorite sources) noted in his Evolution: What the Fossils Say And Why It Matters, due to the incompleteness of the fossil record (and I'll add, because evolution is a branching process that creates a complex "bush" pattern of related species instead of being a straight line process producing a ladder-like progression), there is almost never any way for us to know for certain if a specific transitional is the direct ancestor of more recent groups. This is why transitional fossils are those that exhibit features that reveal the transitional anatomical characteristics of actual common ancestors of different taxa, instead of necessarily being actual ancestors.
For clarities sake, such closely-related taxa that do not share the same common ancestor are known as "sister" taxa.
IOW, Tiktaalik may well represent some late-surviving "relic" rather than be the direct ancestor but that does not detract from it being a transitional form in any way, shape or form. It still serves to exhibit traits found in both the ancestral and descendant taxa.
1. Some times individual scientists get sloppy and use terms that aren't scientific like "missing link" or slip and use a term in the popular meaning, but that does not mean that there are two accepted definitions for it in science. Just like everyone else scientists are human and to use such slips as some sort of aha! gotcha moment is unethical in the extreme. But then again, what else can you expect from such documented disreputable sources as Evolution News.Last edited by rogue06; 01-25-2021, 04:05 PM.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by lee_merrill View PostThough I may still invoke common design instead of common descent!
We can invoke anything we want; the question is whether we can provide evidence that makes anyone else want to pay attention to us.
* I mean, doesn't this look like a great explanation for just about anything?
Blue_meanie_leader.png"Any sufficiently advanced stupidity is indistinguishable from trolling."
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Originally posted by lee_merrill View PostActually, the author says biologists have two different definitions of a transitional form, a hard definition (an actual intermediate), and a soft definition (a morphological intermediate, which may not be an actual intermediate). He then takes biologists to task for switching definitions when it turns out that Tiktaalik may not be an actual intermediate, without acknowledging that the definition has been switched.
Though I may still invoke common design instead of common descent!
Blessings,
LeeGlendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
Comment
-
Originally posted by rogue06 View PostIf you had simply done as I asked and gone to any reputable site you'd find that there is no such thing as a "hard definition" and "soft definition" in biology. That is utter bilge.
In biology it refers to any organism that displays characteristics that are commonly found in both an ancestral group and its derived descendant group. It does not have to be the progenitor of the descendant group itself, it just needs to display the traits found in both groups. As I said in post #27
It doesn't have to be a direct ancestor. It could even be an evolutionary dead end.
Blessings,
Lee
"What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)
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Originally posted by lee_merrill View PostI did do what you asked, and found two instances that match the "hard definition."
And this is the soft definition.
Blessings,
Lee
A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.
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