Many of their genes are the same.
Bones and fossils
The strong evidence for the common ancestry of all vertebrates is THE SIMILARITY OF THEIR EMBRYOLOGICAL STAGES.
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.
Scientists can study common ancestry through artifacts like fossils, genetic similarities, and anatomical structures in species. Fossils provide evidence of extinct species, genetic similarities show shared ancestry between organisms, and anatomical structures reveal common traits inherited from a common ancestor.
If organisms have similar genes, then they are closely related.
fossil evidence :)
The comparisons between the anatomies of various organisms show common ancestry which supports evolution.
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.
Simularities in DNA sequence