During the past few years, palaeontologists have agreed first that a land route was present between North and South America during the latest Cretaceous, and that this route still existed during the Palaeocene. Thus far, studies dealing with this problem have been based on tetrapod vertebrates only. In this study, data provided by tetrapods are listed and reevaluated. Moreover, information provided by fresh water fishes are taken into account. The terrestrial bridges which linked North and South America by latest Cretaceous and Palaeocene times probably comprised the Greater Antilles and the Aves Ridge which consisted of a magmatic submitted to uplift and deformation between North and South America at that time. Part of this arc began to collide with both North and South America during the Campanian, an age which corresponds to the beginning of the faunal interchanges. Another volcanic arc was present at that time on the southwestern margin of the Caribbean plate but it was very probably highly discontinuous and therefore could not act as a land bridge. -from English summary