Abstract

Ichthyosaurs were pelagic marine reptiles with a global distribution through most of the Mesozoic. Cretaceous Ichthyosauria are mostly known from the northern hemisphere, although findings from the southern hemisphere have been reported from Australia, Argentina, Chile, and New Zealand. Despite these findings that have contributed to knowledge of the clade, there is still a dearth of information about the evolution, phylogenetics, and ecology of Cretaceous ichthyosaurs from the Southernmost Pacific margin of Gondwana. A Lower Cretaceous locality next to the Tyndall Glacier, inside Torres del Paine National Park, southernmost Chile, has yielded 87 ichthyosaur skeletons to date. Most of the specimens recorded from this area are complete and articulated, however, they are affected by recent weathering and the constant erosion. Here we describe a complete platypterygiine ichthyosaur, which we provisionally assign to Myobradypterygius hauthali von Huene, 1927. The specimen was excavated from the border of the glacier in Patagonia during March and April 2022 and corresponds to the first complete excavated ichthyosaur from Chile. This specimen additionally preserves gastrointestinal contents and is the only Hauterivian (131 Ma) ichthyosaur documented to date containing the articulated skeleton of a preserved fetus. This research increases the knowledge of the paleobiology of the species. In addition to morphology, it contributes information regarding paleoecology and paleopathology, diet, and reproduction in M. hauthali, a taxon potentially restricted to the Pacific margin of Gondwana.