Ojoraptorsaurus

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Ojoraptorsaurus Temporal range: Late Cretaceous, 69 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Silhouette showing the pubis bones
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Superfamily:	†Caenagnathoidea
Family:	†Caenagnathidae
Genus:	†Ojoraptorsaurus Sullivan et al., 2011
Species:	†O. boerei
Binomial name
†Ojoraptorsaurus boerei Sullivan et al., 2011

Ojoraptorsaurus is a genus of oviraptorosaurian dinosaur from the late Cretaceous. Ojoraptorsaurus is only known from pubic bones found at the Naashoibito Member of the Ojo Alamo Formation dating to the early Maastrichtian, about 69 million years ago. It was first named by Robert M. Sullivan, Steven E. Jasinski and Mark P.A. van Tomme in 2011 and the type species is Ojoraptorsaurus boerei. The generic name combines a reference to the formation with a Latin raptor, "plunderer", and a Latinised Greek saurus, "lizard". The specific name honours oceanographer Arjan Boeré who found the specimen.^[1]

The holotype of Ojoraptorsaurus is SMP VP-1458, an incomplete pair of fused pubes. Due to the fusion of the pubes, this specimen is believed to have been a mature individual. Most caenagnathid species are known from very few remains, and Ojoraptorsaurus is no exception. The holotype was compared to well-described pubic remains of other oviraptorosaurians, namely Microvenator, Epichirostenotes, Nomingia, and CM 78001 (now known as Anzu).^[1] It shares with the latter three taxa an enclosed fossa on the inside edge of the pubis near the acetabular rim, a trait which may be diagnostic to caenagnathids (in which case Nomingia is a caenagnathid). Ojoraptorsaurus's fossa is further away from the acetabular rim than those of the other species, a feature characteristic to the genus. Among compared oviraptorosaurians, Ojoraptorsaurus is most similar to Epichirostenotes, a genus differentiated from Chirostenotes in the same paper that Ojoraptorsarus was described in. By comparing pubic proportions with those of CM 78001 (Anzu), Ojoraptorsaurus has been estimated to have been about 1.8 to 2.1 meters (5.9 to 6.9 feet) in length, about 20% smaller than Epichirostenotes.^[1]

In its 2011 description, Ojoraptorsaurus was suggested to differ from other caenagnathids due to possessing the following autapomorphies:^[1]

• A “spoon-shaped” depression on the anterior dorsal surface of the pubic boot.
• An enclosed fossa on the inside edge of the pubis which lies 1 centimeter away from the acetabular rim.
• The portion of the pubic shaft directly above the pubic boot being slightly anteriorly convex.
• A sub-trapezoidal iliac peduncle articular surface of the pubis.

In 2024, Funston, Williamson & Brusatte suggested that, even though Ojoraptorsaurus could be seen as distinct due to its unique stratigraphic position and provenance, it should be considered a nomen dubium since none of the supposed unique features are actually diagnostic for caenagnathids, and some may result from taphonomic distortion.^[2]

• Timeline of oviraptorosaur research