Protosuchus vs Modern Crocodile

[Metal Minister]

I recently was discussing the evolution of crocodiles, and couldn't get a very good answer. I was told that the oldest crocodile fossil was from around 55 million years ago,(after the last great extinction event) and yet a quick search turned up this animal (Protosuchus) from 240 million years ago:




View attachment 128078



My question is, that at looking at this fossil, as compared to a modern crocodile skeleton:



View attachment 128079


We see they are remarkably similar. I don't understand, in the context of evolution, that everything changes or evolves over time, and yet in 240 million years, it appears the crocodile has changed precious little. In order to better understand this, please explain how this is possible. I'm very confused because I keep hearing that dinosaurs turned into birds, and such, over millions of years, yet the crocodile seems all but untouched. Any help you can offer is great, but please keep the links to a minimum, and the answers short, because I unfortunately just don't have time to chase down reams of information. Thank you in advance!

 

[serge546]

Evolution through natural selection occurs through adaptations which are fixed into the population if they offer a selective advantage. If they provide a disadvantage, they do not become fixed and no change in the population occurs.

Thus, the basic design of the crocodile is already highly adapted to its environment and there is no selective pressure for changes to that design. Changes in this design might even be disadvantageous.

 

[Wiccan_Child]

I recently was discussing the evolution of crocodiles, and couldn't get a very good answer. I was told that the oldest crocodile fossil was from around 55 million years ago,(after the last great extinction event) and yet a quick search turned up this animal (Protosuchus) from 240 million years ago:




View attachment 128078



My question is, that at looking at this fossil, as compared to a modern crocodile skeleton:



View attachment 128079


We see they are remarkably similar. I don't understand, in the context of evolution, that everything changes or evolves over time, and yet in 240 million years, it appears the crocodile has changed precious little. In order to better understand this, please explain how this is possible. I'm very confused because I keep hearing that dinosaurs turned into birds, and such, over millions of years, yet the crocodile seems all but untouched. Any help you can offer is great, but please keep the links to a minimum, and the answers short, because I unfortunately just don't have time to chase down reams of information. Thank you in advance!

Within evolutionary theory, there is a concept called 'punctuated equilibrium'. It basically holds that, most of the time, environmental conditions are stable, and this stability (or 'equilibrium') is punctuated with brief moments of change (for instance, an area that's been cold for a million years becomes warm over 100 years, and stays warm for a further 1 million years).

Another facet of evolution is that species only undergo large morphological change if there is a reason to. If the environment is stable, once the species evolves and becomes optimal for that environment, there's usually little reason to evolve radically new forms. There's an optimal fur length, for instance, and once that's been attained, fur length won't change unless the environment does.

Thus, if there's a case where the environmental niche that a species lives in doesn't change for millions of years, then the species itself may well not change in any large, morphological fashion for millions of years.

So species can change in large and obvious ways, but they don't always, especially if there's no reason for them to.

 

[Jamin4422]

Within evolutionary theory, there is a concept called 'punctuated equilibrium'.

According to Eldredge "anti - intellectualism" is the "myth that traditional technological advancement implies similar progress in all things". In terms of evolution and punctuated equilibrium this translates into meaning that progress or changed in one area does not mean progress or change in all areas.

Often we have species that from the time of their explosion or radiation to the time of their extinction they remain unchanged.

 

[Jamin4422]

Evolution through natural selection occurs through adaptations which are fixed into the population

You see that is the problem. Even if all science agrees that evolution HAS taken place. They do not all agree on HOW life evolves. In fact the reason Evolution is a theory is because it is in a constant state of change. Theories change, facts remain consistent and do not change.

 

[RickG]

You see that is the problem. Even if all science agrees that evolution HAS taken place. They do not all agree on HOW life evolves. In fact the reason Evolution is a theory is because it is in a constant state of change. Theories change, facts remain consistent and do not change.

Keep telling yourself that so you can remain in your comfortable state of willful denial; and I don't mean denial of evolution, I mean your choice to ignore all science that is inconvenient for you.

We know quite a bit how life evolves and why, that is what makes the theory so strong. All science is based on theory. You have had it explained to you many times that a scientific theory is as good as science gets and that theories are always adding newly discovered information. That doesn't mean what was known is wrong, it means that things are now better understood and that understanding will become much much clearer in the future as new information is added.

Yes theories change, that is what makes them stronger. Yes facts do not change because a fact is just that a fact. Theories contain many facts and continue to accumulate more and more facts as they are recognized or discovered.

A theory not changing would be a problem, not the fact that you think they should not change.

 

[USincognito]

I recently was discussing the evolution of crocodiles, and couldn't get a very good answer.

Be honest, apart from something like "we don't know and we're making this up" or "Creationists are right", is there any answer you would have considered "good"?

I was told that the oldest crocodile fossil was from around 55 million years ago,(after the last great extinction event)

Whoever told you that was off by a bit. Crocodilia, the order that includes crocs, alligators and gavials goes back to about 85 million years.
Crocodilia - Wikipedia, the free encyclopedia

and yet a quick search turned up this animal (Protosuchus) from 240 million years ago:

Yes. Protosuchus has the characteristics that make it a likely ancestral split from generically reptilian beings into ones that would eventually become crocodiles.
Protosuchus - Wikipedia, the free encyclopedia

As an early crocodile relative, its skull featured more crocodilian characteristics than its earlier ancestors; it had short jaws that broadened out at the base of the skull, providing a large surface to which its jaw muscles could attach. This increased the maximum gape of the animal's mouth and the force with which the jaws could be closed. The dentition of the animal also resembled modern crocodiles, including the teeth in the lower jaw that fitted into notches on either side of the upper jaw when the mouth was closed.[1] It also possessed a powerful tail which later developed into a propulsion mechanism through water in its descendants.

Note how the description doesn't say it was a modern crocodile.

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My question is, that at looking at this fossil, as compared to a modern crocodile skeleton:

{snip attachment}

We see they are remarkably similar.

Really? I know layman Creationists will point to certain tranistional or basal fossils and a modern descendant and/or analogue and say "they look exactly the same". Leaving aside for a moment the fact that paleontologists look at specifics like bone structure, muscle attachments, characteristics like shape, size, etc. that a casual observer might think "look exactly the same", if one looks at the fossil Protosuchus, they don't look anything like a modern croc or even a Cretaceous Crocodilia. The artists reconstruction on the Wikipedia page
Protosuchus - Wikipedia, the free encyclopedia
looks more like an iguana than like a modern croc, alligator or gavial.

I don't understand, in the context of evolution, that everything changes or evolves over time, and yet in 240 million years, it appears the crocodile has changed precious little.

Every being and species changes just a little bit over time. Some (insert taxon here) change slower than others. Darwin noted this with the finches 150+ years ago so I have no idea why Creationists still struggle with this. In certain environmental niches, there is no selective pressure for major changes in body plan. If you can continue to eat things, digest them, and have enough energy to find a mate and produce offspring, your body plan is working just fine.

That said, as I showed above, basal Crocodilians have changed a lot in the last 240 million years. They have had the same general body plan for about 85 million, but there have been many variants since then.

In order to better understand this, please explain how this is possible. I'm very confused because I keep hearing that dinosaurs turned into birds, and such, over millions of years...

Question before going into bird evolution. Is it your understanding that sauropods "turned into birds" or are you familiar with all the evidence that supports theropods evolving wings from their diminished forelimbs? We can more easily address your lack of understanding if it's based on reality rather than a straw man.

...yet the crocodile seems all but untouched.

They haven't. See above.

 

[Jamin4422]

I mean your choice to ignore all science that is inconvenient for you.

So you want me to continue to quote Eldredge for you. Because without Eldredge you would not even HAVE a theory of evolution. Although it is difficult for me to read Eldredge because he is more radical of a evolutionist then you are. But he still calls your argument "anti-intellectualism". It is simply a myth that advances in one area means advances in all areas of science. In many areas science is still very much behind the times. So it is clear that progress in one area does not mean progress in all areas.

We all know how the Media shows science as bad guys about ready to destroy or take over the world at any moment. Then you have people who want their latest gizmo gadget enough that they are willing to put up with toxic waste dumps. Then you have science that likes to perpetuate the myth that they are somehow privy to special knowledge that makes them self important so that they are the only ones that know the truth. They almost deny anyone the right to know of the internal fights that go on.

Anyways, to make a long story short. If what your selling is "we are the experts trust us" then thanks but no thanks I will pass on that for now. I trust in the scientific method and I say apply the scientific method to the Bible and lets see what results you get. Clearly there is a double standard here as to when they use the scientific method and when they don't. So as long as they continue to violate their own standard, then I say keep an eye on them and do not trust them. Verify everything for yourself.

 

[Wiccan_Child]

According to Eldredge "anti - intellectualism" is the "myth that traditional technological advancement implies similar progress in all things". In terms of evolution and punctuated equilibrium this translates into meaning that progress or changed in one area does not mean progress or change in all areas.

I disagree with Eldredge with his definition of anti-intellectualism, but I agree with the point - progress in one area doesn't always mean progress in another. I would have thought that so obvious as to go without saying, but I guess Eldredge (whoever he is) thought otherwise. I'm also confused what it has to do with evolution - did anyone say that a species changes in all its particulars?

To refer back to the OP, crocodiles haven't undergone much large morpholohical change, but they almost certainly have changed on a biochemical lever - adaptations to new food sources, diseases, etc.

Often we have species that from the time of their explosion or radiation to the time of their extinction they remain unchanged.

Indeed, as evolution allows and punctuated equilibrium demands.

 

[RickG]

So you want me to continue to quote Eldredge for you. Because without Eldredge you would not even HAVE a theory of evolution. Although it is difficult for me to read Eldredge because he is more radical of a evolutionist then you are. But he still calls your argument "anti-intellectualism". It is simply a myth that advances in one area means advances in all areas of science. In many areas science is still very much behind the times. So it is clear that progress in one area does not mean progress in all areas.

We all know how the Media shows science as bad guys about ready to destroy or take over the world at any moment. Then you have people who want their latest gizmo gadget enough that they are willing to put up with toxic waste dumps. Then you have science that likes to perpetuate the myth that they are somehow privy to special knowledge that makes them self important so that they are the only ones that know the truth. They almost deny anyone the right to know of the internal fights that go on.

Anyways, to make a long story short. If what your selling is "we are the experts trust us" then thanks but no thanks I will pass on that for now. I trust in the scientific method and I say apply the scientific method to the Bible and lets see what results you get. Clearly there is a double standard here as to when they use the scientific method and when they don't. So as long as they continue to violate their own standard, then I say keep an eye on them and do not trust them. Verify everything for yourself.

No, you are taking my comment completely different from my intent. I'll state it again. You accept the scientific facts that support your views and reject or criticize those that do not fit your views. This rejection is done through subjective personal bias, not supporting empirical evidence.

I suggest stating why you reject certain aspects of science and provide supporting evidence from the scientific literature rather than biased opinion.

 

[Naraoia]

We see they are remarkably similar. I don't understand, in the context of evolution, that everything changes or evolves over time, and yet in 240 million years, it appears the crocodile has changed precious little.

In this case, it has changed from a smallish, long-legged, short-snouted terrestrial carnivore to a large, flat-skulled aquatic one (Also, FWIW, Protosuchus is actually younger than 240 million years, if you check the age range on the Paleobiology Database.)

By the way, the diversity of crocodiles in their Mesozoic heyday might surprise you. Notosuchians (which are not, strictly speaking, crocodylians) are a good place to start if you want a taster. (That Wikipedia page has a nice table with thumbnail images of many genera.) Also, here's a bunch of crocs that went all the way in terms of aquatic adaptation - paddles for feet, tail fins, loss of armour and all: Metriorhynchidae - Wikipedia, the free encyclopedia

In order to better understand this, please explain how this is possible. I'm very confused because I keep hearing that dinosaurs turned into birds, and such, over millions of years, yet the crocodile seems all but untouched. Any help you can offer is great, but please keep the links to a minimum, and the answers short, because I unfortunately just don't have time to chase down reams of information. Thank you in advance!

I kind of ended up going on a lot longer than I wanted to, but on the plus side you can get what I'm saying without clicking any of the links below

Short answer: there is no law of nature saying that evolution must always proceed at the same speed.

If a design works, there's no reason for it to change. Evolution still doesn't stop in these groups - DNA sequences are going to differ, bodies and physiologies are going to adapt to their particular surroundings. There's a reason Protosuchus isn't even classified in the same order as modern crocodiles.

Very slow morphological change may also hide a lot of genetic change, as some people have argued about tuataras.

The variable rates of evolution are old news to anyone working with molecular sequences. Some lineages evolve much faster than others. Some genes evolve much more rapidly than others. For a couple of examples from each end of the spectrum:

(1) Sex-related genes have a tendency to evolve quickly. These bindin protein sequences (bindin is involved in egg-sperm recognition) in two closely related sea urchins have quite a few differences.

(2) Genes involved in the core information storage and processing mechanisms in a cell are often much more conserved. Histone H3 protein sequences (important in DNA packaging and gene regulation) from a plant and an animal are almost identical.

Parts of a gene/protein can evolve at different rates, too, depending on their function. For example, you may have heard of Hox genes, which are extremely important developmental control genes, and how you can transfer them between distantly related species and they'll still work. Well, one such experiment replaced the labial gene in fruit fly embryos with its chick counterpart. It worked almost as well as the original fly gene. It may surprise you, then, that out of the hundreds of amino acids in each protein, only about 70 can even be aligned - the rest of the sequences don't match at all. Those 70 are the DNA-binding domain and a small motif involved in protein-protein interaction.

Protein-coding sequences in general change more slowly than many non-coding regions. Some parts of a chromosome undergo mutations and rearrangements more often than others. Repetitive DNA is very mutation-prone. And so on. You could probably spend an entire semester on the types and causes of variation in evolutionary rates

ETA: I almost forgot - morphological traits can also vary in their intrinsic "evolvability" (BTW, that's an actual technical term). Here's a selection experiment in which butterflies were bred for different combinations of eyespot traits. Turned out that the size of different eyespots could evolve pretty much independently - if the front eyespot grew over the generations, that didn't stop the rear eyespot from getting smaller etc. However, the colour composition of the different eyespots could only change in concert: they couldn't breed butterflies that had lots of black in one spot and lots of yellow in another.

 

[Jamin4422]

In this case, it has changed from a smallish, long-legged, short-snouted terrestrial carnivore to a large, flat-skulled aquatic one

You have two fossils, so what evidence do you have that one changed into the other?

 

[Naraoia]

You have two fossils, so what evidence do you have that one changed into the other?

The croc fossil record contains a bit more than two species.

 

[Gadarene]

It was I who posted the 55 mya bit - I apparently got mixed up between the Crocodylidae family and the Crocodilia order.

Crocodile - Wikipedia, the free encyclopedia

 

[Shemjaza]

We see they are remarkably similar. I don't understand, in the context of evolution, that everything changes or evolves over time, and yet in 240 million years, it appears the crocodile has changed precious little.

You have two fossils, so what evidence do you have that one changed into the other?

C1: These are the same!

E: No they aren't.

C2: They are Different... how do we know they are related!


I'm seeing a pattern of "Evolution is wrong because it is wrong".

 

[Metal Minister]

C1: These are the same!

E: No they aren't.

C2: They are Different... how do we know they are related!

I'm seeing a pattern of "Evolution is wrong because it is wrong".

An over simplification at best. I keep seeing pretty much the same thing though. They are very similar (changed very little) but if mutations are inevitable, then why do so few come up with certain animals like the crocodile? I keep seeing natural selection, but this is weak at best. We see poor mutations survive in other animals just fine, so what would make crocodiles special? I may be missing it but it sounds like I'm getting "Evolution works when we see major changes" on one hand and then "Evolution works when we don't see major changes" on the other. You see I'm asking questions, and other than a few posters here (which I greatly appreciate the information from) I'm getting a lot of angst and the basic stereotypical "you just don't know science" jargon. Not really a good way to help people learn now is it...

 

[Shemjaza]

An over simplification at best. I keep seeing pretty much the same thing though. They are very similar (changed very little) but if mutations are inevitable, then why do so few come up with certain animals like the crocodile? I keep seeing natural selection, but this is weak at best. We see poor mutations survive in other animals just fine, so what would make crocodiles special? I may be missing it but it sounds like I'm getting "Evolution works when we see major changes" on one hand and then "Evolution works when we don't see major changes" on the other. You see I'm asking questions, and other than a few posters here (which I greatly appreciate the information from) I'm getting a lot of angst and the basic stereotypical "you just don't know science" jargon. Not really a good way to help people learn now is it...

But we established that this critter while similar, is by no mean identical. "Long flat scaly thing with sharp teeth" may describe both the extinct species and modern crocodiles, but they are hardly "identical".

Also we never say "evolution always makes fast changes" or "evolution never makes fast changes" situations are different and species need to adapt different amounts to the environments they find themselves in.

What I don't understand is that if evolution was made up and it didn't make sense that Protosuchus existed millions of years ago, why would we say that? If it were a lie we were perpetuation because we want to have science orgies or worship Satan wouldn't we have just said "Oh, Protosuchus? that's just another sort of normal crocodile from 2 thousand years ago."

 

[Wiccan_Child]

An over simplification at best. I keep seeing pretty much the same thing though. They are very similar (changed very little) but if mutations are inevitable, then why do so few come up with certain animals like the crocodile? I keep seeing natural selection, but this is weak at best. We see poor mutations survive in other animals just fine, so what would make crocodiles special? I may be missing it but it sounds like I'm getting "Evolution works when we see major changes" on one hand and then "Evolution works when we don't see major changes" on the other.

That's because evolution makes a lot of different things happen. In some cases, it makes change (such as when a population's average fur length increases as the environment gets colder). In others, it makes a species stay the same (such as when the environment is static, and so any mutations are deviations from the optimum).

The crocodile has changed a lot, but on the inside; its external physiology simply hasn't needed to change, so it hasn't. It's by no means perfect - you can disable one with a rubber band - but it does the job.

 

[Naraoia]

No, I can do much more than troll.

How 'bout you?

I think MM has done a pretty good job of not trolling so far, so the answer would be so can he.

 

[Jro]

An over simplification at best. I keep seeing pretty much the same thing though. They are very similar (changed very little) but if mutations are inevitable, then why do so few come up with certain animals like the crocodile? I keep seeing natural selection, but this is weak at best. We see poor mutations survive in other animals just fine, so what would make crocodiles special? I may be missing it but it sounds like I'm getting "Evolution works when we see major changes" on one hand and then "Evolution works when we don't see major changes" on the other. You see I'm asking questions, and other than a few posters here (which I greatly appreciate the information from) I'm getting a lot of angst and the basic stereotypical "you just don't know science" jargon. Not really a good way to help people learn now is it...

Mutations are inevitable during the act of reproduction, but that doesn't mean that it's inevitable that those genes will become fixed in the population. If, for example, they are deleterious to an organism's fitness, they will be reduced in frequency and if they are advantageous to their fitness that gene frequency will be promoted, absent instances of genetic drift. So this means that whether a mutation takes over a population or is extinguished is very context dependent. What might be an advantageous mutation for one population or species could spell death for another. Even within populations, the same mutation might give an advantage in one environment, and become fixed in that local population, while being disadvantageous in another environment, and become wiped out in another.

A good way to think about it is to look at the different types of selection that can occur on a population. Here is a good visual showing the effects of different types of selection on an imaginary creature.