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Alternative land vertebrates from mudskippers; In a world where tetrapods never appear
Topic Started: Mar 6 2010, 09:18 AM (1,232 Views)
Dean
Infant
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So, here's the deal: There's an alternate universe which is different from our world by two things:

1. This universe is younger than ours by 406 million years (hence the Earth in this world is like our Earth was during the Devonian).


2. The groups "Tetrapodomorpha" and "Dipnoi" never evolve.


Now, a group of modern mudskippers from our world are teleported to this world, to the place where in our world, tetrapodomorphs eventually started evolving into more and more survivable-on-land species.

What do you think what kind of forms would they evolve into, when they start conquering the land instead of Tetrapods?

Since mudskippers are members of Actinopterygii, they'd need to evolve some really clever methods to make prolonged existence on land possible, different from what we are familiar with, with early tetrapods.
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Holben
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Rumbo a la Victoria

Although i'm not sure about the ageing universe, here you go.

Mudskippers' locomotion isn't very efficient, and works best on soft ground. The first systems would spring up around riversides and beaches, probably preyed upon by scorpion-like invies. They might grow a protein shell or covering which would help them survive attacks and burrow into the ground. Swimming, ammonite-like forms maybe?

Perhaps some start developing shelled eggs. They are nourished by an algae-like symbiont which lives with the creature throughout its life. (Improbable, i know. But it sounds cool)

And locomotion- the legs may duplicate to allow lizard-like swing walking, or become more erect and become bipedal, non armed creatures. 'Armless.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Dean
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Good ideas!

Since hind legs have nothing to develop from, maybe snake-like forms who simply lose the other two legs and resort to sidewinding would evolve very early.

Or erect bipeds who walk on their "arms". That'd look very funny. :) Imagine a lizard-like fish quickly walking on it's arms.

Some could resort to moving back to into the water and becoming more like other fish.


I wonder, would any form eventually able to break ties with the water completely (except for drinking) and become an amniote-analogue?

By the "younger universe" I meant that in this world, the Big Bang simply happened 406 million years later than in ours, hence the Earth here is still in the Devonian. No "different laws of physics" stuff here.
Edited by Dean, Mar 6 2010, 02:42 PM.
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Margaret Pye
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"I wonder, would any form eventually able to break ties with the water completely (except for drinking) and become an amniote-analogue?"

Mudskippers don't have lungs (as in primitive-for-bony-fish lungs, obviously not tetrapod lungs), do they?

Do they use cutaneous respiration?

Maybe they'd evolve into tripods, standing on the fins and the tail?
Edited by Margaret Pye, Mar 7 2010, 06:35 AM.
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

When wet, they can breathe through their skin. Let me find a source-
Quote:
 

The ability to breathe through their skin and the lining of their mouth (the mucosa) and throat (the pharynx). This is only possible when the mudskipper is wet, limiting mudskippers to humid habitats and requiring that they keep themselves moist.


From wikipedia, as ever.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Margaret Pye
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Well then, could they evolve lungs out of cutaneous diverticulae?
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

The number of subcutaneous diverticulae thingimajigbahoolas means that they would cause the entire creature to swell up. If you're thinking a few would expand and become anchored on muscles, they could combine with the muscles around the stomach to help them in- and ex-hale. But i think their 'swim bladders' would be more easily modified.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Margaret Pye
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I did mean a few large ones.

Do mudskippers have swim bladders?
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

la la la la la, source finding...

Erm, well, they
Quote:
 
retain a bubble of air. These large gill chambers close tightly when the fish is above water, keeping the gills moist, and allowing them to function. They act like a scuba diver's cylinders, and supply oxygen for respiration also while on land
- wikipedia

Not really a swim bladder as such.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Margaret Pye
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Right! Those are practically primitive lungs already!
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

Not as such, they're is still a bit of modification needed to remove the need for water dissolved oxygen.

But they're doing better than most fish, not forgetting the lungfish.

Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Ook
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in project will be in tropical coasts and mangrove forest descendants of mudskippers.They have got in that ecoystems same roles as frogs and newts in freshwater rivers,lakes...they ale on half way to elvove into paralel amphibians
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Margaret Pye
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No no, you don't remove the water. You just reduce the water to a very, very thin layer, and you've got lungs.
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Dean
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If they can't evolve a real air-breathing lung from those gill chambers, they will be "reverse-dolphins". Dolphins are land animals who ventured back into the water, but because of being amniotes and warm-blooded, they must depend on air breathing.

These land-mudskippers could radiate into many kinds of lissamphibian-kind of forms, but if a real lung can't develop from these gill chambers, or the swim bladder can't turn into a lung, they can't turn as independent from the water as amniotes.


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Margaret Pye
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The gill chambers definitely sound like they could evolve into lungs, though.

Or of course, there are all those little salamanders with no lungs, who breathe entirely through their skins. Only works at small sizes, but mudskipper descendants could do the same.
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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