Bridging the southern gap: first definitive evidence of Late Jurassic ichthyosaurs from Antarctica and their dispersion routes

Abstract

New ichthyosaur remains from the Upper Jurassic of Antarctica, recovered from the Ameghino (=Nordenskjold) ¨Formation are described. These three new specimens represent the first unambiguous records of ichthyosaurs in this continent. Based on the morphology of the humerus, we refer one of the specimens to Ophthalmosauridae, the dominant ichthyosaur forms from the Middle Jurassic until the extinction of the group during the Late Cretaceous. In addition to the new Antarctic records, we re-evaluate ichthyosaur remains of two individuals from the Upper Jurassic of Madagascar and describe a third new specimen, which is the most complete ichthyosaur from this region of Gondwanaland. These findings provide new insights into the role of the seaways opened during the Jurassic in the dispersion of ichthyosaurs, particularly ophthalmosaurids. Antarctic and Malagasian ichthyosaurs bring additional support to the hypothesis of the Mozambique Corridor acting as a dispersal route connecting the Tethys Sea and the southern Pacific margins of Gondwana, at least since the Late Jurassic.