> Possibly even more pedantic, have you noticed how, even though the authors clearly know the difference between polygyny and polygamy, they seem to somtimes use both terms interchangeably?

Bu they don't: the authors of the "Media Release", who are writing for the general public using language as familiar as possible, use the term "polygamy", but never in quotes from the authors of the study -- which always use "polygyny". The study itself always uses "polygyny" (and, at least at one point, more specifically "non-sororal polygyny"); the only times "polygamy" (or related forms like "polygamous") appear in the paper itself are in discussions of what other others studies found, one mention discussing forms of pair-bonding as "monogamous and polygamous", and in titles of works cited.