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Tetrapods evolved fingers from the inner-bones of the fins of lobe-finned fish, could hands ever evolve from ray finned fishes if they were to become fully terrestrial, from a mud skipper ancestor?

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  • $\begingroup$ Yes, given enough time, anything can evolve from anything. It's why we have the diversity we have today. $\endgroup$
    – Kilisi
    Mar 12 '20 at 3:46
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A group of anglerfishes known as handfishes walk on the sea floor with their remarkably hand-like pectoral fins. However, handfishes are strictly aquatic.

Frogfishes, another group of anglerfishes, can walk slowly on the sea floor with either their pectoral fins or by using a combination of their pectoral and pelvic fins. Like their handfish relatives, frogfishes never venture onto land and can not breathe air.

Yet another anglerfish group called batfishes use their pectoral, pelvic and anal fins to walk on the sea floor, but like their cousins, they can not leave the water.

Although it does not have particularly hand-like fins, the mangrove rivulus can survive for 2 months out of the water by breathing through its skin. It can not walk though, it has to move by flipping itself.

The walking catfish, Clarias batrachus, belongs to an entire family of airbreathing catfishes. While this species technically does not walk, it does use its pectoral fins to keep itself upright while it traverses dry land with snake-like movements. The walking catfish is covered in mucus, which protects it when it is out of the water.

Bichirs, the most primitive ray-finned fishes, have paired lungs, and walk across the floor of their aquatic environment. The pectoral fins are even strong enough to allow for short-distance travel across land.

Some cottid sculpins can spend up to 24 hours on land.

Snakeheads can breathe air and can travel over dry land if their current environment becomes inhospitable.

Blennies, particularly those in the genera Alticus and Andamia, can breathe air and spend hours on land. They have to be kept moist though and will suffocate if they dry out.

In mudskippers, the radials are elongated, producing a limb with a shoulder and a wrist. Mudskippers can breathe through their skin and the lining of their mouth, but only when they are wet. They also have enlarged gill chambers that close tightly when out of the water, keeping the gills moist.

It is very plausible that a mudskipper or even bichir could evolve into terrestrial animals with hands. With a few more structural alterations, these fishes wouldn't be much different from the first basal tetrapods.

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