Hyaenodonts were the first carnivorous mammals to appear in Africa, arriving after non-avian dinosaurs like Tyrannosaurus rex went extinct some 65 million years ago. Not closely related to big cats, hyenas, bears or dogs, hyaenodonts ruled the continent of Africa for an incredibly impressive 45 million years before going extinct as the global climate dried up and forests were replaced by grasslands.
The fossilized remains sat in a drawer in a Kenyan museum for over 40 years before anyone took a closer look at them. (Credit: Ohio University).