Buitreraptor (meaning "La Buitrera seizer") is a genus of dromaeosaurid dinosaurs that lived during the Late Cretaceous of Argentina at the Candeleros Formation. Buitreraptor was described in 2005 and the type species is Buitreraptor gonzalezorum. It was rooster-sized and had a very elongated head with many small teeth.
Four specimens of Buitreraptor were found in 2004 in sandstone in Patagonia, Argentina during an excavation led by Sebastián Apesteguia, researcher of CONICET at the Fundacion Felix de Azara - Maimonides University, and Peter Makovicky, curator of dinosaurs at the Field Museum in Chicago. Buitreraptor is from the early Late Cretaceous Candeleros Formation, dating to the Cenomanian-Turonian ages approximately 98 to 97 million years ago, when South America was an isolated continent like Australia today. It was uncovered in a famous fossil site named La Buitrera, the "vulture roost". Although dinosaurs are rare in this site, another nearby site had earlier yielded the giant Giganotosaurus, one of the largest known carnivorous dinosaurs.[1]
Buitreraptor gonzalezorum is the only known species of the genus Buitreraptor. It was named by Peter Makovicky, Sebastián Apesteguía and Federico Agnolín. The genus name means "vulture raider", from the Spanish word buitre meaning vulture, in reference to La Buitrera, and Latin raptor, "seizer". The specific name honours the González brothers, Fábian and Jorge, who realised much of the actual excavation and preparation of the fossils.[1] The holotype specimen, MPCA 245, consists of a partial skeleton with skull of an adult individual. The paratype is MPCA 238, a sacrum with a right pelvis and right hindlimb.[1] The skull of the holotype was described in detail in 2017,[2] while 2018 saw a slew of new papers on the anatomy of the genus. These include descriptions of new specimens,[3] a study on the tail anatomy of the genus,[4] and a general overview of the postcrania of multiple specimens.[5]
Buitreraptor was a rather small dinosaur. In 2010, Gregory S. Paul estimated the length at 1.5 metres, the weight at three kilograms.[6] Buitreraptor has some different physical features than typical northern dromaeosaurs, such as Velociraptor. Buitreraptor has a slender, flat, extremely elongated snout with many small teeth that lack meat-tearing serrations or cutting edges and are grooved, strongly recurved and flattened.[7][8] From this, the scientists who initially described it concluded that this dinosaur was not a hunter of relatively large animals like some other dromaeosaurs, but rather a hunter of small animals such as lizards and mammals. The forelimbs of Buitreraptor were long and ended in very long and thin three-fingered hands. All known parts of the hand of Buitreraptor are proportionally longer than in the dromaeosaurids Deinonychus and Velociraptor, except for the ungual bones which are proportionally smaller in Buitreraptor.[3]
The body as a whole was also elongated, with a shallow ribcage. The enlarged sickle claw at the second toe of the foot formed a blade that was long although less large than in dromaeosaurids such as Velociraptor and Deinonychus.[3] No fossil discoveries have been made of any feathers of Buitreraptor. However, there are relatives like Microraptor and Sinornithosaurus, of which fossils with preserved feathers are known. Since its close relatives had feathers, it is likely that Buitreraptor also was feathered. According to Apesteguia, this is comparable to reconstructing an extinct monkey with fur because all modern monkeys have fur.[9]