The strong evidence for the common ancestry of all vertebrates is THE SIMILARITY OF THEIR EMBRYOLOGICAL STAGES.
Simularities in DNA sequence
True, they descend from a common ancestor.
It does hint at common ancestry so it is "evidence" of evolution.
Simularities in DNA sequence
It simply highly suggests that all organisms going through this developmental phase have common ancestry, thus are related on the tree of life.
Many of their genes are the same.
If organisms have similar genes, then they are closely related.
fossil evidence :)
limbs wings legs arms and flippers
That different organisms are able to adapt to the same environment.
I do not know. I can look at shared biochemical pathways and see direct evidence of common ancestry with other organisms.
Fossil evidence