A DIACHRONIC ACCOUNT OF EXCEPTIONAL PROGRESSIVE NASALIZATION PATTERNS IN GUARANI CAUSATIVES 1 Bruno Estigarribia University of North Carolina at Chapel Hill Nasal harmony in Paraguayan Guarani spreads mostly leftward in a morphological word. This regressive nasalization is triggered by a phonologically nasal consonant or stressed na- sal vowel and does not affect voiceless stops. A limited process of progressive nasalization affects morpheme-initial voiceless stops across a morpheme boundary. Many forms that in- clude a causative prefix show this kind of progressive nasalization. However, this nasal spread lacks any obvious nasal trigger and does not occur consistently. In this paper, I pro- pose an explanation of these cases as vestiges of earlier phonological rules from pre-Proto- Tupi-Guarani but not active in Paraguayan Guarani, followed by the emergence of a regres- sive oralization rule and ending in a reanalysis of the basic form of the causative prefix. In so doing, I will provide a revised sequence of changes involving contour allophones in the re- construction of Proto-Tupi-Guarani (PTG). [Keywords: nasal harmony, Tupian, prenasalized consonants, aperture theory, sandhi] 1. A puzzle involving nasal harmony in Paraguayan Guarani. Modern Paraguayan Guarani (ISO 639-3: gug; autonyms Avañe'ẽ ‘language of men’, Guaraní; henceforth PyG) is, with around 6 million speakers, the most widely spoken language of the Tupi-Guarani (TG) family. 2 As is common in TG, PyG shows nasal harmony: phonologically nasal segments (the source or trigger) in a root or prefix cause some non-nasal segments in the phonological word (the targets) to become nasal (1). 3 1 Acknowledgements: Fieldwork for this study was funded by a National Endowment for the Hu- manities (USA) fellowship award, #FEL-257415, the Buchan Excellence Fund administered by the University of North Carolina Department of Romance Studies, and the Schwab Excellence Award from UNC’s College of Arts and Sciences. I would like to thank my colleague Ernesto López Almada for providing recordings of the Paraguayan Guarani examples in this paper. Finally, my heartfelt thanks for the anonymous reviewers and editors of this manuscript for their excellent work. 2 The Tupi-Guarani (TG) family is composed of approximately 40–50 languages, with a very wide geographical distribution due to extensive migration. Speakers of TG languages are present in Argentina, Bolivia, Brazil, French Guiana, Paraguay, and Peru (Jensen 1998; Mello 2000; Gua- rani Ñe’ẽ Rerekuapavẽ 2018). Despite this geographical spread, the TG family is morphologically remarkably consistent (Jensen 1998). 3 Since morphophonemics are important in this paper, the PyG examples will be presented as fol- lows: the first line gives an established orthography; the second line gives a phonetic representation (separating phonological words); the third line presents a morphemization (using the allomorphs considered the underlying forms); the fourth line presents the analysis of the parsed elements; and the fifth line gives a free translation into English. For other languages, all of this information may [IJAL, vol. 87, no. 2, April 2021, pp. 203–241] DOI 10.1086/712976