A nearly 40-million-year-old skeleton belonging to what is popularly called a sabre-toothed tiger has sold for $84,350, a year after its discovery on a US ranch. The skeleton, about 120 centimetres (nearly four feet) long, was snapped up by a private collector in just one minute at an auction in Geneva on Tuesday.  The original bones are those of a Hoplophoneus -- not technically cats, they are an extinct genus of the Nimravidae family and once stalked the plains of North America. Such extinct predatory mammals are commonly known as sabre-toothed tigers.