Xenotarsosaurus, scientifically known as "Xenotarsosaurus bonapartei," is a genus of theropod dinosaur that lived during the Late Cretaceous period, approximately 83 million years ago. The name "Xenotarsosaurus" is derived from Greek words "xenos," meaning "strange" or "foreign," and "tarsos," referring to the bones in the ankle joint, which sets it apart from other theropods. The specific epithet "bonapartei" honors the renowned Argentine paleontologist José Bonaparte, who played a key role in the discovery of this dinosaur.

The fossil remains of Xenotarsosaurus were first unearthed in the Huincul Formation of Argentina, adding to the intriguing diversity of prehistoric life in South America.

Xenotarsosaurus exhibited distinctive features that set it apart from other theropod dinosaurs of its time. As a carnivorous dinosaur, it walked on two powerful hind limbs, indicative of its bipedal stance. Its forelimbs were relatively small and likely used for grasping prey and manipulating objects.

One of the defining characteristics of Xenotarsosaurus is its unique ankle structure, represented by fused bones in the ankle joint. This adaptation is rare among theropods and contributed to its scientific name.