How Lardil got its deletion rules; how the rules got their exceptions

Lardil is renowned for its ordered, synchronic rules of deletion, where a rule of word-final vowel deletion feeds rules of final consonant deletion. One might suppose that this reflects ordered diachronic sound changes of vowel loss followed by later consonant loss, but comparative evidence reveal that this is not the case. Rather, the consonant deletion rules existed already in proto-Tangkic, where they applied word-finally. Additionally, a vowel deletion rule, which affected only a, applied phrase-finally. The diachronic change in Lardil involved an extension of the vowel deletion rule to other vowel qualities, motivated by other language-internal changes, and from phrase-final to all word-final positions, in line with the currently understood typology of diachronic domain shifts in rules (Bermúdez-Otero 2015). We then turn to exceptions to these rules. After some minor cases, we turn to the larger class of word-final a vowels which escape deletion and instead undergo raising to u. Hints of related alternations appear when cognates are compared across the Tangkic family, and can be accounted for in unexceptional terms as follows. Stems ending originally in phonemic Cuwa, where C is labial or velar, had an unsurprising range of phonetic realisations, as Cuwa~Cwa~Ca. When the stem was suffixed, thus the word was longer, the phonetic realisations may have favoured the shorter Cwa~Ca. When word-final vowel deletion applied to phonemic Cuwa, the result was word-final Cu, which alternated with pre-suffixal phonetic Cwa~Ca. Later, within the overall Lardil phonological system, this would naturally have been reanalysed as underlying Ca which idiosyncratically raises to Cu word finally, thereby giving rise to the exception to the deletion rule.