The revision by Hiller et al. (2005) of the species Mauisaurus haasti Hector (Plesiosauroidea, Elasmosauridae) from the Late Cretaceous of New Zealand, has provided reliable postcranial characters that permit recognition of this taxon as distinct among Late Cretaceous elasmosaurid plesiosaurs from both the Northern and Southern hemispheres. Particularly, in adult specimens, the femur displays a large, hemispherical capitulum that seems to be autapomorphic. This unique morphology is present in at least two specimens recovered from Late Cretaceous (Maastrichtian) beds in central Chile, which these fossils may be referred to the same taxon with confidence. The Chilean fossils are considerably larger than those from New Zealand, suggesting either difference in ontogenetic age or interspecific variation. The studied material constitutes the second accurate generic identification of elasmosaurid plesiosaurs from the eastern margin of the Pacific Ocean, thus complementing the known south−gondwanic paleodistribution of Mauisaurus during the Late Cretaceous.

Rodrigo A. Otero [paracrioceras@gmail.com], Museo Paleontológico de Caldera. Av. Wheelwright 001, Caldera, Chile; Sergio Soto-Acuña [arcosaurio@gmail.com], Laboratorio de Zoología de Vertebrados, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago, Chile; David Rubilar-Rogers [drubilar@mnhn.cl], Museo Nacional de Historia Natural, Interior Quinta Normal s/n, Santiago, Chile.