Buitreraptor (meaning "La Buitrera seizer") is a genus of unenlagiine theropod 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.
History of discovery
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.
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.
Description
Buitreraptor was a rather small dinosaur. In 2010, Gregory S. Paul estimated the length at 1.5 metres, the weight at three kilograms.
[Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 139] 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.
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
and
. 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.
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.[ National Geographic: "New Birdlike Dino Adds to Debate on Origins of Flight", 18-10-2005.]
Classification
Buitreraptor shows a mosaic of dromaeosaurid,
Troodontidae and
Avialae traits. It was in 2005 assigned to the
Dromaeosauridae. A
cladistic analysis by the describers showed it was part of the dromaeosaurid
Unenlagiinae.
The discovery of
Buitreraptor has also been the subject of discussion among scientists as to the question whether flight could have evolved independently in birds and dromaeosaurids or was derived from some flying common ancestor. Some scientists propose that
Rahonavis, a relative to
Buitreraptor, could fly. However, evidence for flight has not been unequivocally found in other dromaeosaurids, which has led some scientists to propose that dromaeosaurids evolved flight independently of birds if
Rahonavis could indeed fly.
[ New Scientist: "Feathered flight, so good they did it twice?", 15-10-2005.]
The following cladogram is based on the phylogenetic analysis conducted by Hartman and colleagues in 2019, showing the relationships of Buitreraptor among the other genera assigned to the family "Unenlagiidae":
Evolution
Other than
Buitreraptor, the only other known dromaeosaurs from the southern continents are
Neuquenraptor,
Austroraptor, and
Unenlagia from South America (discovered earlier in 2005),
Rahonavis (once thought to be a true avian bird) from
Madagascar, and unidentified dromaeosaur-like teeth from Australia. This discovery in the Southern Hemisphere helped scientists to clarify that the dromaeosaur family was more widely dispersed around the world than previously thought. Evidence indicates that dromaeosaurs first appeared during the
Jurassic Period, when all the continents were much closer together than they are today. With the discovery of
Buitreraptor, the scientists proposed that dromaeosaurids originated somewhere around 180 million years ago, before
Pangaea broke up.
[ EurekAlert!: "Newly discovered birdlike dinosaur is oldest raptor ever found in South America: Relative of Velociraptor rewrites evolutionary charts", 12-10-2005.] However, other paleontologists have in later studies placed the time of origin for Dromaeosauridae to about 160 million years ago.
The scientists see it as an alternative possibility that dromaeosaurids originated on the ancient continent Laurasia in the north and during the Cretaceous Period migrated to southern Gondwana, since the species known from the Southern Hemisphere bear distinctive characteristics not shared by their northern relatives. La Buitrera also yielded remains of terrestrial crocodiles, pterosaurs, the largest known , limbed snakes, lizards, chelidae turtles, mammals, and lungfish fishes
Paleobiology
Unenlagiines had better capacities for running and pursuit predation than other dromaeosaurids such as
Laurasian dromaeosaurids (
Eudromaeosauria), which were more stocky and had shorter legs and had an active predatory lifestyle. Unenlagiines were highly
cursorial animals because they were more gracile and had modified metatarsals that are relatively thin and lengthened.
Based on these adaptations, it is likely that unenlagiines preyed on small, fast animals, although the exact animals are unknown.
Buitreraptor might have been capable of powered flight, as discussed in a 2025 study.[Motta, Matías J.; Agnolína, Federico L.; Eglia, Federico Brissón; Rozadillaa, Sebastián; Novas, Fernando E. (22 Aug 2025). "Phylogenetic relationships of Unenlagiidae among Paraves (Dinosauria)". Journal of Systematic Palaeontology. 23 (1). doi:10.1080/14772019.2025.2529608. Retrieved 22 August 2025.]
See also
-
Timeline of dromaeosaurid research
External links
