Long before the cataclysmic space-rock crash marked the end for the dinosaurs, mammals had already begun to spread out across the ever-changing planet. One mammal that roamed with the dinosaurs during the Cretaceous was a fuzzy guy called Vintana sertichi, a groundhog-like critter that lived in Madagascar.
No one knew the creature existed until scientists found a nearly complete skull in 2010. As scientists began to study V. sertichi, they determined that it was larger than most mammals that lived with the dinosaurs, weighing in at 20 pounds (9 kilograms). One scientist even called it "Punxsutawney Phil on steroids."
V. sertichi belonged to a group of mammals known as Gondwanatherians, which developed on the land mass known as Gondwana. That great swath of land eventually broke apart into Africa, Antarctica, South America, Madagascar, India, Arabia and Australia. Scientists speculate that V. sertichi developed in isolation, causing it to have strange but interesting features, such as a tilted brain case and a tremendous sense of smell [sources: Drake; Encyclopedia Britannica].