This paper gives clear synchronic evidence for the origin of serial verb constructions (SVCs) in Emerillon, a Tupi-Guarani language. SVCs in that language result from a gerundive construction after the loss of both a subordinator and an indexation pattern specific to dependent clauses. After a short review of the general literature on the origins of SVCs and their similarity to converbs (of which Tupi-Guarani gerundives may be considered a subtype), the author gives a detailed account of the Emerillon SVCs. Strong arguments then show that Emerillon serial verbs (superficially comparable to independent verbs) originate from a 'deranked' dependent clause. The paper ends with some discussions on clause linkage, comparing more specifically SVCs and converbs on the morphological, syntactic and functional levels.