A cast of the skull of the mammal Vintana sertichi, left, and a life reconstruction Gary Staab with Staab Studios. The skull of the previously unknown mammal was found in Madagascar. (AP Photo/Stony Brook University, Joseph Groenke)
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.