[aculeus]

... we may have been inadvertently omitting a huge amount of information about all of the soft-bodied animals that were swimming around in the water column, munching on other organisms, but which were rarely fossilized.

'Swimming' implies directed movement, something modern jelly fish are incapable of.

'Munching' suggests chewing, of which no jelly fish is capable.

Question unaddressed in this article (and in Biology literature) why didn't they evolve in 500 million years? Unpunctuated equilibrium (as if that would explain anything)? Or something else?

[RightWhale]

why didn't they evolve in 500 million years?

There was a mass extinction about 250 million years ago that wiped out not just entire species, but entire FAMILIES all over the planet. It was much bigger than the dinosaur extinction. Maybe that has something to do with it.

[aomagrat]

The foolish Humans have discovered an ancient crash site.

[mykej]

Question unaddressed in this article (and in Biology literature) why didn't they evolve in 500 million years?

Because they didn't need to. They survived just fine without changing. Evolution is not about going from simple to complex or from "worse" to "better". It is about surviving in your enviroment long enough to reproduce.

[lds23]

My folks went to the quarry and all I got was this T-Shirt:

[BluesDuke]

Oops! I saw the thread name, Jelly turned to rock, and thought it was something to do with a politician's brains...