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Pladcoderm evolution; Remember the armored fish?
Topic Started: Sep 11 2008, 08:37 AM (3,174 Views)
Spartan Delta
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I had a thought. Does anybody remember the pladcoderm fish from the Devonian, like Dunkleosteus?
Well, what if they were able to get on land first? I imagined a T-Rex like biped with fins for this...
What do you think?
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leptonosoma
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They would have to develop legs for walking on land.
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Carlos
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Placoderms couldn't possibly become land dweelrs; they lacked every single adaptayion our ancestors had for such evolutionary step, like bony skeletons and a swimming bladder that could become a lung. Plus, will all that armour...

However, if the other fish groups had died out instead of them, they could very well dominate the seas. I imagine several species of placoderms occupying the niches of modern fish: shark like placoderms, ray-like placoderms, marlin-like placoderms, etc.
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http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

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Livyatan


Pretty much what John said...yeah...
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Sliver Slave
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I'm going back to basics.

While the feasibility of land placoderms may be in doubt here, a couple of people have come up with land placoderm concepts. I'll see if I can dig them up.

Also, what about the antiarchs? Maybe they could drag themselves up? Except they're bottom dwellers.
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Rodlox
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Sliver Slave
Sep 11 2008, 05:19 PM

Also, what about the antiarchs? Maybe they could drag themselves up? Except they're bottom dwellers.

so are frogfish and batfish - wouldn't being bottom-dwellers make it easier to develop "limbs" or "feet"?
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Carlos
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Not really; placoderms didn't had the bony fins that bony fish have
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

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SIngemeister
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I just had a weird Tub Gurnard/Dunkleosteus cross image.
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Vultur-10


Perhaps the small ones could have adapted to tidepools, developing their boneless fins into something like a snail's "foot"?
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Carlos
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Even so, they are would be very far from becoming like tetrapods.

Besides, there's no evidence that no fish other than bony fish have/had swim bladders, which are required for the evolution of lungs
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

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Spartan Delta
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Sliver Slave
Sep 11 2008, 05:19 PM
While the feasibility of land placoderms may be in doubt here, a couple of people have come up with land placoderm concepts. I'll see if I can dig them up.

Also, what about the antiarchs? Maybe they could drag themselves up? Except they're bottom dwellers.
I have just one question: What are antiarchs?

And now I get my problem. Sorry. '^^ I'll have to redo my design.

Still, tho, do you think that that jaw design could make a good asset for a land predator, or what problems would there be?
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PousazPower
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I don't think anyone's mentioned the most obvious attribute of the placoderms--the armor. This would pose a great problem to an animal trying to support itself on land for the first time, and it probably wouldn't be able to move around at all, let alone lead to a line of "neotetrapods".

To The Chieftain: Antiarchs are placoderms whose pectoral fins are enclosed in bony sheathes that look suspiciously like arthropod legs. Here: http://www.palaeos.com/Vertebrates/Units/Unit060/060.200.html
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Carlos
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Also, I think everyone's forgetting that bony fish are so far the only known fishes with swim bladders, which was what become the lungs of the tetrapods...
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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PousazPower
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I don't think lungs would be that hard to evolve as gut diverticula, but you do have a point.
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Spartan Delta
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PousazPower
Sep 20 2008, 01:25 PM
I don't think anyone's mentioned the most obvious attribute of the placoderms--the armor. This would pose a great problem to an animal trying to support itself on land for the first time, and it probably wouldn't be able to move around at all, let alone lead to a line of "neotetrapods".

To The Chieftain: Antiarchs are placoderms whose pectoral fins are enclosed in bony sheathes that look suspiciously like arthropod legs. Here: http://www.palaeos.com/Vertebrates/Units/Unit060/060.200.html
Oh, ok! Sorry, I'm not that knowledgeable of the pladcoderms. That, and school makes research time hard to get. '^^

Oh, and about the armor, I actually think that if the legs were armored, then a dragging motion would be able, right? And it's not that big a jump from sprawling to erect walking.

And if not a pladcoderm, then could any OTHER creature evolve that style of bone-crunching head gear for a jaw?
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