Abstract

Expeditions to the Tyndall Glacier (Torres del Paine National Park, South Chile) in 2009 and 2010 recov-ered an articulated ichthyosaurian forefin that displayed traits consistent with Platypterygius. The combination of features observed in this forefin has not been observed in other Platypterygius species, i.e.: (1) one preaxial row and three or even four postaxial rows; (2) the distal articulation of ulna with metacarpal five; (3) the shape and the articula-tion context of distal carpal three, metacarpal three and four; (4) the hexagonal shape of the intermedium; and (5) the presence of only two distal articular facets on the humerus. Nevertheless, the forefin is not referred to a new species, because it was found isolated and no other diagnostic skel-etal elements are present. The forefin presented here is the first complete and articulated forefin of a Platypterygius from the South Pacific margin, and together with other ichthyosaurs from the Tyndall area, represents the southern-most occurrence of Early Cretaceous ichthyosaurs in the Americas.