| Named By: | Calvo, GonzalezinRiga, Kellner & Porfiriin 2007 |
| Time Period: | Late Cretaceous, 87 Ma |
| Location: | Argentina, Neuquen Province |
| Size: | Estimated about 26 meters long |
| Diet: | unavailable |
| Fossil(s): | Three specimens |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Sauropodomorpha | Titanosauria | Lognkosauria | |
Futalognkosaurus ( FOO-ta-long-ko-SAW-ras; meaning "giant chief lizard") is a genus of titanosaurian dinosaur. The herbivorous Futalognkosaurus lived approximately 87 million years ago in the Portezuelo Formation, in what is now Argentina, of the Coniacian stage of the late Cretaceous Period. The fish and fossilized leaf debris on the site, together with other dinosaur remains, suggest a warm tropical climate in Patagonia during this period.