On pg. 408 in discussing the desideratives in -uriō, I mention that the short u of this suffix violates Latin phonotactic constraints since the only short vowel normally permitted before an r in a medial syllable is e. As I mention in the footnote there are of course obvious analogical cases like augur, auguris, but there is perhaps another source for this sequence. Original u like all short vowels became e (*swekurī 'father-in-law' gen. sg. > socerī), presumably by general weakening to i and lowering before, but if a labiovelar, and presumably also the labiovelar glide, precedes the medial vowel the outcome is u, e.g. *per-kwatiō > percutiō, iekwVna:num > iecunanum (glossed victimarium (Fest. p. 114 M) and derived from the old oblique stem of iecur according to Alan Nussbaum p.c.). What would happen if a u of this sort were followed by an r? There are no clear cases but it is possible that if the u arose after or as the result of weakening, as is likely, it would be retained. A potential case might be decuria if from *dekwiria (more about that elsewhere). This idea doesn't lead immediately to an immediate solution to the -uriō question, but it does open some interesting vistas.