To my fellow feline furries, I send a good-natured: "Ha!" :)
The study compared 12 animal samples, including pufferfish. Why pufferfish? Surely we're not closely related to these fish... Did they happen to have a sample around the lab and figured it'd be good for laughs? I suspect, though they don't say anywhere, that this was to establish some sort of baseline for the farthest-removed DNA sequence.