Different in degree or kind: Egnor's take; more on gaps (Introduction)

by David Turell , Thursday, October 20, 2016, 15:13 (2956 days ago) @ dhw

dhw: I think they do refer to the only one that made the PERMANENT transition. For me the crucial point is that primitive lungs and legs already existed as organisms tried to cope with different environmental conditions.

DAVID: Of course a lung had to appear. We should be discussing the actuating cause of the lung.

dhw: My hypothesis, in line with the cases we know of, is that environmental conditions caused organisms to make the changes. Here’s a website explaining the advantages of primitive lungs, which obviously have a long history.

1. How did fish evolve lungs? - Quora
https://www.quora.com/How-did-fish-evolve-lungs

Sorry, but I've read your article, which is filled with Darwin-speak. A swim bladder is a swim bladder, not a lung. Evolution to lung is assumed. Where is the provable research? Not in fossil evidence.