The Bidensaurus, Bidensaurus mactabilis, is a small, striped, nocturnal gorgonopsid from the uplands of Skull Island. It measures 5-6 feet long.
The Bidensaurus is a dog-sized nocturnal predator closely related to the Lycaesaurus of the lowlands and the impressive fan-backed Gladiodon. These carnivores are solitary, except in the breeding season, when mated pairs might stay together for several months. A Bidensaurus uses an acute sense of smell to sniff out small or sleeping large prey in the dead of night.