[D] Unquillosaurus ceibalii [sG] [T]
Cretaceous Late ?Campanian
Saurischia Theropoda Incertae Sedis \\\"Carnosaurs\\\"
Los Blanquitos Formation, Salta, Argentina
Genus - Typespecies
An isolated left pubis, is the type specimen of Unquillosaurus ceibalii. Proximally just below the iliac articular surface is a marked, cranioventrally-facing sulcus, quite unlike anything known in other theropod pubes.
From: Powell, J. E. 1979. Sobre una asociacion de dinosaurios y otras evidencias de vertebrados del Cretácico superior de la region de La Candelaria, prov. de Salta, Argentina. Ameghiniana 16(1-2):191-204. [On a dinosaur association and other evidinces of Upper Cretaceous vertebrates from the La Candelaria region, Salta Province, rgentina]
Translated by Matthew CarranoSUNY at Stony Brook, 8/99
It refers to the Unquillo river, to which the streams which drain the area of the locality come together.
Pubis with proximal expansion cut by a canal in the anterolateral part. Obturator foramen open. External face of the shaft crossed by a prominent longitudinal crest. Pubic \\\"foot\\\" without anterior projection.
Unquillosaurus ceibalii sp. nov.
PVL 3670-11. A left pubis .
It refers to El Ceibal, the place closest to the locality.
Upper beds of the Los Blanquitos Formation.
The pubis of this species is long and slender, endowed with expansions on both ends. The proximal expansion has an incomplete ischial process that is directed backwards and down. On its superior face a concave surface is observed that corresponds to the pubic portion of the acetabulum. The inferior face of this process is excavated, emphasizing a deep channel that is directed from above and forwards to below and back.
The inferior border of the ischial process surrounds the recess of the obturator foramen, in a manner similar to that shown in Allosaurus, among others (Madsen, 1976).
Viewed from the front, the pubis is curved with the convexity oriented outwards. Laterally it shows a prominent crest that extends from the anterior end of the proximal expansion and becomes lost when it arrives at the distal third of the bone. This crest delimits a surface in front that is planar above and convex below, where it is narrower.
The \\\"foot\\\" of the pubis does not have an anterior projection and is expanded briefly backwards. Its lateral surface is divided into two facets. The smaller, anterolateral facet is separated medially by means of an obtuse edge from the other, laterally-located facet. The planar medial face fits against the corresponding one on the opposite pubis to form the symphysis.
Up until now, no carnosaur pubis was known from the Cretaceous of South America, for which reason its comparison has been made difficult to a certain extent. The pubis of Unquillosaurus ceibalii is notably differentiated from those of most known theropods by the presence of a deep channel on its proximal end. Its short \\\"foot\\\" is different from those of large theropods such as Allosaurus, Tyrannosaurus, and Albertosaurus. The possession of an open obturator foramen is similar to Allosaurus (Madsen, 1976), Marshosaurus (Madsen, 1976), and other theropods.
Considerations on the Arroyo Morterito fauna: The presence of an association of dinosaurs in this locality permits widening the panorama on the faunistic composition of the Upper Cretaceous of regions near the tropics in South America. On the other hand, it permits comparison of this association with that of El Brete (Bonaparte and Powell, 1978), which includes sauropods, carnosaurs, coelurosaurs, and birds. This locality is also localized in the south of Salta province, and therefore corresponds to the Lecho Formation, a unit that covers the Los Blanquitos Formation in the valley of the Salta Group. The available elements indicate that these two associations have no common forms. Those of Arroyo Morterito correspond to individuals of medium-large size, while those of El Brete are of a more modest size.
\\\"Carnosaurs\\\" have rarely been documented in the Upper Cretaceous of South America. In northwest Argentina the presence of carnosaur teeth has been cited in the Yacoraite Formation of Aguas Calientes (Bonaparte and Bossi, 1967 and this work) and in the Lecho Formation of El Brete (Bonaparte et al., 1977; Bonaparte and Powell, 1978). Unquillosaurus ceibalii constitutes the first clear evidence of the presence of Carnosauria based on postcranial remains. Source: Polyglot Paleontologist
Novas, F. E., and Agnolin, F. L. (2004) Unquillosaurus ceibali Powell, a giant maniraptoran (Dinosauria, Theropoda) from the Late Cretaceous of Argentina: Rev. Mus. Argentino, Cienc, Nat. N.s., V. 6, n. 1, p. 61-66. Suggests Unquillosaurus is possibly a dromaeosaurid .