Síntesis del registro fósil de dinosaurios tireóforos en Gondwana

Abstract

of stegosaurs, ankylosaurs, and basal forms such as Scelidosaurus. Thyreophorans have a long fossil record, extending from theLower Jurassic to the Upper Cretaceous. Most of the fossils come from localities in the Northern Hemisphere. However, the thyreophoranrecord of Gondwana includes significant skeletal remains and tracks in South America, Africa, Madagascar, Australia, New Zealand and Antarc-tica. Thyreophorans could be present in Africa since the Early–Middle Jurassic. They are well documented in the Upper Jurassic of Tanzania(stegosaur Kentrosaurus) and the Jurassic–Cretaceous transition of Bolivia (tracks). Stegosaurs were present in South Africa (Paranthodon) andArgentina (indeterminate form) during the Early Cretaceous, whereas ankylosaurs were present at this time in Australia (Minmi). Ankylosaurshave been recorded in the Late Cretaceous of South America (body fossils in Argentina and tracks in Bolivia), Antarctica (Antarctopelta), NewZealand, and likely Madagascar. The presence of both ankylosaurs and stegosaurus in India needs to be confirmed. From a palaeobiogeo-graphical point of view, it seems that Gondwanan thyreophorans come from different migrations from Laurasia. The African stegosaurs couldbe the result of two independent dispersal events during the Middle–Late Jurassic. The Gondwanan ankylosaurs do not come either froma single radiation: Minmi may represent a relictual Jurassic ankylosaur lineage in Australia prior to the dichotomy Nodosauridae-Ankylosauri-dae, whereas the Argentinian and Antarctic nodosaurids probably represent one or several Late Cretaceous dispersals between North andSouth America