The top 10 most common fears include aversions to quite a few creatures from the animal kingdom. In fact, arachnophobia (the fear of spiders) is the single most commonly reported fear. It's followed by ophidiophobia (the fear of snakes) and cynophobia (the fear of dogs). While it doesn't crack the top 10, the fear of sharks is also common. Bears, however, are rarely mentioned in the discussion of our worst fears.
That would likely change if more people knew about Simbakubwa kutokaafrika, the terrifying hunter and scavenger that roamed the African plains 22 million years ago. The animal has been described as a combination of a lion and a bear, but it actually belongs to a now-extinct order of mammals called hyaenodonts. The Simbakubwa kutokaafrika was the largest of that order - larger than a modern polar bear.
Size is one thing, but the Simbakubwa was also an apex predator. The fierce creature was a hypercarnivore, which is defined as an animal that gets over 70% of its diet from meat. Although the Simbakubwa may be one of the most frightening, beautiful animals, it's likely that the very qualities that made it so vicious are also what led to its extinction.