This paper offers a detailed account of a change from non-finite to finite dependent clauses in Emérillon, a Tupi-Guarani language spoken in French Guiana, and presents it as the syntactic context within which loss of ergativity occurred. It shows that the previously described change of the indexation system within dependent clauses in some Tupi-Guarani languages (Jensen 1990), from ergative to both split-intransitive and hierarchical, is in fact only one piece of a considerable shift in dependency-coding strategy. I argue that, whereas Proto-Tupi-Guarani dependent constructions were non-finite, they shifted towards finite clauses in Emérillon. I describe the gradual shift labeled finitization, i.e. a gain of finiteness features, involving not only person markers, but also TAM, negation and clause-linking markers. The change in alignment system is therefore presented as a non-autonomous change within a wider diachronic syntactic shift in dependency-coding.