You’re welcome. I think that paper was groundbreaking because it showed how prokaryotes can “invent” new genes without the benefit of extra DNA. The phenomenon is now called “overprinting” and involves frame shifts as Ohno found in 1984. According to this recent paper, we now have four known examples of this. Overprinting shows how easy it is (in principle) for new genetic information to arise through small changes, even in environments like bacterial genomes where there is almost no unused genetic material sitting around.
Most eukaryotes, and basically all animals, have gigantic amounts of non-coding DNA from which to accidentally discover new coding sequences. So we animals have many more opportunities to create a new domain or an entirely new gene overnight. I admit I used to think that this was probably pretty rare. But I think I was wrong; see some of these recent open access papers:
Origins of De Novo Genes in Human and Chimpanzee
The Recent De Novo Origin of Protein C-Termini
Disclosure: a kid of mine is a grad student in the Masel lab, which published the last paper.