Evolution's Brick Wall

[Job 33:6]

Regarding the morphological differences between ceolacanth of the devonian and species today:

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1525-142X.2007.00169.x
A new fossil from the Middle–Late Devonian of Wyoming preserves the first and only example of a primitive coelacanth pectoral fin endoskeleton. The strongly asymmetrical skeleton of this fin corroborates the hypothesis that this is the primitive sarcopterygian pattern, and that this pattern persisted in the closest fish‐like relatives of land vertebrates. The new material reveals the specializations of paired fins in the modern coelacanth, as well as in living lungfishes. Consequently, the context in which these might be used to investigate evolutionary and developmental relationships between vertebrate fins and limbs is changed. Our data suggest that primitive actinopterygians, rather than living sarcopterygian fishes and their derived appendages, are the most informative comparators for developmental studies seeking to understand the origin of tetrapod limbs.


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1560029/
Previously considered an actinopterygian or an osteichthyan incertae sedis, the Devonian (Givetian–Frasnian) Holopterygius nudus is reinterpreted as a coelacanth. This genus is among the oldest coelacanths known from articulated remains, but its eel-like morphology marks a considerable departure from the conventional coelacanth body plan. A cladistic analysis places Holopterygius as the sister taxon of the Carboniferous (Serpukhovian) genus Allenypterus. Despite the specialized morphology of these genera, they occupy a surprisingly basal position in coelacanth phylogeny; only Diplocercides and Miguashaia are further removed from the crown. A morphometric analysis reveals that coelacanths were anatomically disparate early in their history. Conflicts between this result and those of previous studies challenge the adequacy of systematic character sets for describing historical patterns of morphological variety. Coelacanths have long had an iconic place in the study of vertebrate evolution for their apparent anatomical conservatism over geological time, but Holopterygius provides clear evidence for rapid morphological evolution early in the history of this clade.

Widely cited studies place coelacanths as the most basal extant sarcopterygian radiation (Cloutier & Ahlberg 1996; Forey 1998), but little is known about their early history. While the first crown-group sarcopterygians are known from Lower Devonian (Lochkovian; 411–416 Ma) deposits (Cloutier & Ahlberg 1996), the oldest unequivocal coelacanths are of Givetian age (385–392 Ma; Forey 1998; Long 1999; Forey et al. 2000). Previously described Devonian coelacanths fall into two morphological categories: primitive forms (Gavinia, Miguashaia) with postcrania resembling those of other plesiomorphic sarcopterygians, and more crownward taxa (Chagrinia, Diplocercides) whose postcranial anatomy is similar to that of stratigraphically younger and phylogenetically more derived coelacanths, including the Recent Latimeria.

Holopterygius marks a considerable anatomical departure from other Devonian forms, and a cladistic analysis places it as the sister taxon of Allenypterus, another early coelacanth with unusual postcranial morphology (analysis and results are described in figure 2a).

The postcranial morphologies of Allenypterus and Holopterygius—and presumably their ecologies—differ radically from those of ‘typical’ coelacanths, but this is not reflected in previous measures of disparity.

More remarkable than the degree of morphological separation between Holopterygius, Miguashaia and other early coelacanths is the short interval over which this variety was generated. With a probable origin of actinistians during the Early Devonian or Late Silurian, each of these distinctive morphologies was established by the close of the Middle Devonian. In contrast, post-Carboniferous forms show no evidence of the radical morphological shifts that characterize the initial phases of the coelacanth radiation, despite higher levels of taxonomic diversity (Forey 1998) and a longer interval over which to develop anatomical novelties. The most extreme departure during this later interval is the Jurassic Libys, which, although deep-bodied, conforms to the stereotypical coelacanth body plan. Such rapid accumulation of morphological variety early in clade histories is a recurrent theme in studies of disparity in the fossil record (Foote 1997), but the causes underlying this pattern remain uncertain (Foote 1996). What is clear, however, is that Holopterygius and its disparate contemporaries provide evidence for early anatomical experimentation in coelacanths that is strongly at odds with the textbook portrayal of the clade as morphologically invariant over geological time.

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https://www.tandfonline.com/doi/abs/10.1080/02724634.2012.657317

An unusual fork-tailed coelacanth from the Lower Triassic Sulphur Mountain Formation of British Columbia, Canada, marks the first considerable departure in actinistian body form since the Mississippian Period. Rebellatrix divaricerca, gen. et sp. nov., is unique among coelacanths in its possession of a bifurcated caudal fin, reduced segmentation of fin rays, and fusion of caudal fin elements. Parsimony analysis of a character-taxon matrix of 109 characters and 29 taxa recovered R. divaricerca as sister taxon to Latimerioidei. The family Rebellatricidae is erected to include only R. divaricerca. This novel body shape of the new coelacanth raises questions about the idea that coelacanths were morphologically static following the Mississippian. Rebellatrix divaricerca also emphasizes the morphological diversity of coelacanths during the Early Triassic, a time when species diversity of coelacanths was also highest. The slender, fork-tailed body form suggests fast swimming and an active lifestyle, unique among known fossil and extant coelacanths.


https://onlinelibrary.wiley.com/doi/abs/10.1002/bies.201200145
Here, we have examined the available molecular and morphological data and show that: (i) low intra‐specific molecular diversity does not imply low mutation rate, (ii) studies not showing low substitution rates in coelacanth are often neglected, (iii) the morphological stability of coelacanths is not supported by paleontological evidence.



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Ok, so above are 4 research papers, that actually discuss morphological differences between ceolacanths of the devonian, the carboniferous, extant species and more.

So now that we have cleared up the nonsense about ceolacanth being morphologically the same in the devonian versus those of today, can we go back on subject regarding the predictions involved in determining the locality of tiktaalik? @inquiring mind and @Justatruthseeker

 

[Jimmy D]

Thank you for sharing this article justatruthseeker.

What the heck? In the post prior to that I provided the actual research paper that that short magazine article is discussing, you know the paper entitled....

The African coelacanth genome provides insights into tetrapod evolution

Which refutes Justa's original post that implied that coelacanths were some sort of problem for biologists or some such nonsense.

You guys crack me up!

 

[inquiring mind]

Ok, so above are 4 research papers, that actually discuss morphological differences between ceolacanths of the devonian, the carboniferous, extant species and more.

I think I'll run with the Smithsonian article.

 

[inquiring mind]

What the heck? In the post prior to that I provided the actual research paper that that short magazine article is discussing, you know the paper entitled....

The African coelacanth genome provides insights into tetrapod evolution

Which refutes Justa's original post that implied that coelacanths were some sort of problem for biologists or some such nonsense.

You guys crack me up!

I don’t know Jimmy, the Smithsonian seems to be a big supporter of micro and macro evolution. You’re not suggesting they are mixed up some way, are you?

 

[Job 33:6]

I think I'll run with the Smithsonian article.

The Smithsonian article doesn't say that the devonian ceolacanths are morphologically the same as today's. Unless you're reading some other Smithsonian article that I am unaware of.

The only difference between the Smithsonian article and the research is that the research is written by scientists who study these things, like myself and others here. The Smithsonian article is was probably written by reporters who were simply listening to what the researchers told them, they simplified the language and rehashed it for the public.

But ultimately, the Smithsonian article doesn't say that they're the same.



And again, all of this is irrelevant to discussion of how tiktaaliks locality was predicted.

 

[inquiring mind]

The Smithsonian article doesn't say that the devonian ceolacanths are morphologically the same as today's. Unless you're reading some other Smithsonian article that I am unaware of.

You're right... but it does say "the coelacanth’s genome and outward appearance have only changed slightly in the roughly 400 million years since it first appeared on the planet."

 

[Job 33:6]

You're right... but it does say "the coelacanth’s genome and outward appearance have only changed slightly in the roughly 400 million years since it first appeared on the planet."

That's right. To a lay person, they look similar in that they're both ceolacanths. And when we look at technical reports, we can see that in fact they are different. Just as tetrapods in the devonian are different than tetrapods today, though tetrapods of the past do share many similarities with tetrapods of today.

Ultimately though, as I've said before, the fact that ceolacanths and tetrapods exist today, doesn't contradict evolution. What would contradict evolution, and I'll say it again so everyone can read, what would contradict evolution is if derived tetrapods or ceolacanths were found before ancestral forms of themselves. Or to simplify things , a tetrapod or lobe finned fish like ceolacanth, would have to be found before non lobe finned fish, or in the case of tetrapods , they would have to be found before the fish which they're predicted to have evolved from.

Do you understand what I am saying here^?

 

[Job 33:6]

If tetrapods appeared before fish, or mammals before reptiles or birds before reptiles or reptiles before amphibians or any subgroup of any of the above, it would contradict the theory.


Because evolution would have to explain how a fish with legs came about before fish themselves. It wouldn't make any sense.

But saying that a ceolacanth came after a prior ceolacanth that was morphologically different, doesn't actually contradict the theory. Nor does the existance of modern day fish that look like other prehistorc fish.

@inquiring mind do you understand what I am saying here^?

 

[Justatruthseeker]

That's right. To a lay person, they look similar in that they're both ceolacanths. And when we look at technical reports, we can see that in fact they are different. Just as tetrapods in the devonian are different than tetrapods today, though tetrapods of the past do share many similarities with tetrapods of today.

Ultimately though, as I've said before, the fact that ceolacanths and tetrapods exist today, doesn't contradict evolution. What would contradict evolution, and I'll say it again so everyone can read, what would contradict evolution is if derived tetrapods or ceolacanths were found before ancestral forms of themselves. Or to simplify things , a tetrapod or lobe finned fish like ceolacanth, would have to be found before non lobe finned fish, or in the case of tetrapods , they would have to be found before the fish which they're predicted to have evolved from.

Do you understand what I am saying here^?

You mean just as dogs are slightly different but the same species????

You mean like humans are slightly different but the same species?????

How could it contradict evolution? They have found fossils out of place where they were predicted before and then simply move the timescale back several hundred million years to cover up the fact their theory was falsified.... it’s so fluid it doesn’t even fit the definition of a scientific theory, it’s silly putty that can be molded to fit whatever is found, instead of being molded to fit what is found....

 

[Jimmy D]

I don’t know Jimmy, the Smithsonian seems to be a big supporter of micro and macro evolution. You’re not suggesting they are mixed up some way, are you?

No I’m not suggesting that, what are you talking about?

 

[Job 33:6]

You mean just as dogs are slightly different but the same species????

You mean like humans are slightly different but the same species?????

How could it contradict evolution? They have found fossils out of place where they were predicted before and then simply move the timescale back several hundred million years to cover up the fact their theory was falsified.... it’s so fluid it doesn’t even fit the definition of a scientific theory, it’s silly putty that can be molded to fit whatever is found, instead of being molded to fit what is found....

This is all smoke and mirrors.

As I've said before, a fish appearing after a pre-existing fish of course does not contradict the theory. Nor does the existance of any fish today contradict the theory just because they look kind of like fish in the past.

This is just silly^

And no, mammals have not been found to predate reptiles nor birds before reptiles nor reptiles before amphibians etc.

And if you disagree, show is the research. Or perhaps you think there is some kind of giant conspiracy where I am hiding fossils in my basement from the public haha.

 

[inquiring mind]

That's right. To a lay person, they look similar in that they're both ceolacanths.

First, let me say it sort of feels good to be included with the Smithsonian in this argument. That's pretty good for a self-proclaimed non-expert.

Just as tetrapods in the devonian are different than tetrapods today, though tetrapods of the past do share many similarities with tetrapods of today.

So, you're talking 'micro'?

Ultimately though, as I've said before, the fact that ceolacanths and tetrapods exist today, doesn't contradict evolution. What would contradict evolution, and I'll say it again so everyone can read, what would contradict evolution is if derived tetrapods or ceolacanths were found before ancestral forms of themselves. Or to simplify things , a tetrapod or lobe finned fish like ceolacanth, would have to be found before non lobe finned fish, or in the case of tetrapods , they would have to be found before the fish which they're predicted to have evolved from.

And, we've already discussed at great length from the OP that finding fossils to prove 'macro' evolution seems impossible.

Do you understand what I'm saying?

 

[Job 33:6]

First, let me say it sort of feels good to be included with the Smithsonian in this argument. That's pretty good for a self-proclaimed non-expert.

So, you're talking 'micro'?

And, we've already discussed at great length from the OP that finding fossils to prove 'macro' evolution seems impossible.

Do you understand what I'm saying?

Well remember, the discussion is about tiktaalik it's predicted locality. We are discussing a transition from lobe finned fish, to land based, air breathing tetrapods.

Which isn't micro evolution.

If you want to change the subject and would like to talk about ceolacanth, then sure, you can call it microevolution if you want.

And I am presenting a fossil that proves macro evolution, or at least supports it. Which is how this whole discussion started when I described how the locality of tiktaalik was predicted based on the theory of evolution.

 

[Justatruthseeker]

Huh? Well your first two comments aren't a response. It's just you in denial. Regarding the 3rd statement, they are not calling the ceolacanths the same, morphologically. Where in the paper did you read that?

“The present finding of the slow rate of nucleotide substitution in the coelacanth genome possibly offers insights into why the morphology of coelacanths has evolved so slowly over the past 400 million years (Smith 1939; Forey 1988). Namely, slower nucleotide substitutions in coelacanth genes and/or enhancers may reduce the potential to alter the phenotypic traits.”

So over 400 million years they barely did anything morphological or genetically.

In other words they need an excuse why it hasn’t evolved in 400 million years....

 

[Job 33:6]

The question stands, if evolution did not occur on a macro scale, then what so evolution deniars make of tiktaaliks predicted location?

So far the only response I've heard is "well maybe it was pure chance", which is hilarious because these predictions are accurately made all the time.

 

[inquiring mind]

No I’m not suggesting that, what are you talking about?

Justa's article was a Smithsonian article. I've not looked, who wrote the article you presented? In other words, what are you talking about?

 

[Justatruthseeker]

Well remember, the discussion is about tiktaalik it's predicted locality. We are discussing a transition from lobe finned fish, to land based, air breathing tetrapods.

Which isn't micro evolution.

If you want to change the subject and would like to talk about ceolacanth, then sure, you can call it microevolution if you want.

And I am presenting a fossil that proves macro evolution, or at least supports it. Which is how this whole discussion started when I described how the locality of tiktaalik was predicted based on the theory of evolution.

Your discussing a theoretical change, not an observed change.

In all cases you have distinct fully formed creatures. You connect the dots with imagination, not fact...

 

[Job 33:6]

“The present finding of the slow rate of nucleotide substitution in the coelacanth genome possibly offers insights into why the morphology of coelacanths has evolved so slowly over the past 400 million years (Smith 1939; Forey 1988). Namely, slower nucleotide substitutions in coelacanth genes and/or enhancers may reduce the potential to alter the phenotypic traits.”

So over 400 million years they barely did anything morphological or genetically.

In other words they need an excuse why it hasn’t evolved in 400 million years....

No excuse is needed, because evolution doesn't mandate that a fish evolve into anything vastly different from itself over any extended period of time.

Starfish for example are largely the same now than they were in the past, some at least. But this doesn't contradict the theory. Because nothing in the theory states that things absolutely mist change in grand scales.

 

[Justatruthseeker]

Justa's article was a Smithsonian article. I've not looked, who wrote the article you presented? In other words, what are you talking about?

Which linked to the scientific article in nature....

 

[Job 33:6]

Your discussing a theoretical change, not an observed change.

In all cases you have distinct fully formed creatures. You connect the dots with imagination, not fact...

Then tell me how the prediction of the locality of tiktaalik was made. If you disbelieve.

And @inquiring mind this question is for you too.