I get convergent evolution, but among large (let's say 10g+) organisms, I'm not aware of convergent evolution resulting in compatible species (with fertile offs

I get convergent evolution, but among large (let's say 10g+) organisms, I'm not aware of convergent evolution resulting in compatible species (with fertile offsping) that would not otherwise have been compatible? I'm super rusty on this topic, but if there is theory that large organism actual DNA-level speciation (resulting in individuals who cannot reproduce together) has eventuated to convergence back to a new species (who can reproduce together with fertile offspring), I'd love a source. I definitely could have very rusty knowledge on this but it seems intuitive to me?