Cougar = Puma = Panther = Mountain Lion
Although since the previous use of Puma AND Panther didn't stop Apple from using Mountain Lion, so perhaps Cougar is still valid and for 10.9?
From Wikipedia: "The cougar (Puma concolor), also known as puma, mountain lion, mountain cat, catamount or panther."
Also from Wikipedia: "Extant felids belong to one of two subfamilies: Pantherinae (which includes the tiger, the lion, the jaguar, and the leopard), and Felinae (which includes the cougar, the cheetah, the lynxes, the ocelot, and the domestic cat)."
With this in mind, personally I think only Lynx and Ocelot are the only available cat families available for 10.9, but they seem a bit wimpy for the las X release... They should have saved Lion or Tiger for the last release imo...
Smilodon (Saber-toothed cat) maybe?