Se describen nuevos restos de plesiosaurios (Diapsida; Sauropterygia) incluidos en un bloque rodado correlacionado con estratos superiores de la Formacion Dorotea (Cretacico Tardio, Maastrichtiano), recolectados en la parte sur de la sierra homomma, ubicada al noreste de Puerto Natales (51°41'20,4"S, 72°26'07,4"W), Region de Magallanes, Chile. Se reconoce por primera vez la presencia de la familia Elasmosauridae en altas latitudes de Sudamerica, complementando asi la paleodistribution previamente conocida de este grupo en el margen oriental del Oceano Pacifico y de la Antartica durante la ultima parte del Cretacico Tardio.New remains of plesiosaurs (Diapsida; Sauropterygia) found in a transported block correlated with upper levels of the Dorotea Formation, Late Cretaceous (Maastrichtian) are described herein. They were collected on the southern slopes of Sierra Dorotea located northeast of Puerto Natales (51°41’20,4”S, 72°26’07,4”W), Magallanes Region, Chile. This is the first discovery of the family Elasmosauridae in high latitudes of South America, complementing the previously known paleodistribution of this group in the eastern Pacific Ocean and the Antarctic during the latest Cretaceous.