Back in the dinosaurs' day, mammals were the size of mice. But towering above them was one beefy rodent that one scientist calls "Punxsutawney Phil on steroids"—with super senses to boot. The 20-pound Vintana sertichi was accidentally found in a giant slab of sandstone in Madagascar, reports National Geographic. Researchers were looking for fish fossils, but they found instead Vintana, perfectly preserved and complete. And he's quite odd: Not only is he "humongous," but had superhero sight and very sensitive hearing. But his nose was the best—analysis of Vintana's brain revealed 14% of it was dedicated to smell; dogs only use .31%. "The very exotic combination of its skull features are so beyond our previous imagination," says a paleontologist.
Some of Vintana's more reptilian traits suggest an ancient lineage on the mainland before the species was isolated on Madagascar, where its eccentricities evolved, adds the National Science Foundation. There, it also took on more mammalian features—like a diet of roots, seeds, and nutty fruits, adds the Guardian. Vintana is special for another reason: it's one leaf on an undiscovered branch of the mammalian family tree—the Gondwanatherians. They lived in the southern hemisphere, "a part of the world (of) which we know nothing," says one researcher. "Gondwanatherians were completely unknown 30 years ago," says the paleontologist. LiveScience has these photos. (This dino was king before T. Rex.)