Calvo, Porfiri & Kellner 2004
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Unenlagiinae
Portezuelo Formation, Rio Neuquén Group, Neuquen, Patagonia, Argentina
Unenlagia comahuensis (Novas, 1997) > Unenlagia paynemili (Calvo, Porfiri & Kellner, 2004) >> Neuquenraptor argentinus (Novas & Pol, 2005) >> Araucanoraptor argentinus (Novas, 1997)
The holotype consists of a left humerus (217 mm in length) and a left pubis (267 mm), considered to be of the same animal. A dorsal vertebra, a partial ilium and two pedal elements have been referred. Later, the new taxon Neuquenraptor argentinus has been assigned to Unenlagia paynemili.
Calvo, J.O., Porfiri, J.D. and Kellner, A.W.A. (2003). A close relative of Unenlagia comahuensis (Theropoda, Maniraptora) from the Upper Cretaceous of Neuquén, Patagonia, Argentina. 18º Congresso Brasileiro de Paleontologia, Brasilia, Resumos: 82-83.
Abstract: "The excavation at the ?Futalognko? site, situated at the margins of the Los Barreales lake about 95 km northwest of Neuquén city (Patagonia), revealed several new dinosaur specimens. The sedimentary rocks at that site belong to the Portezuelo Formation (Rio Neuquén Group) and consist of green sandstones intercalated with red mudstones. Among the new specimens recovered during 2002 are the left humerus and pubis of one individual that shares several features with the Maniraptoran Unenlagia comahuensis Novas & Puerta (1997). The humerus of the ?Barreales form? is almost complete, lacking a few parts of the proximal and distal articulations.
Except for being smaller (ca. 20%), this element shows an almost identical morphology to Unenlagia comahuensis. The proximal articulation is large and inflected relative to the main axis; the shaft is straight and slender. The internal tuberosity is anteroposteriorly compressed and longitudinally elongated, similar to the condition observed in Unenlagia comahuensis, Archaeopteryx and Deinonychus. The angle between the distal end of the deltopectoral crest and the shaft in the ?Barreales form? is slightly more closed than in Unenlagia comahuensis.
Based on the proximal articulation, the pubis of the ?Los Barreales form? is oriented vertically what is regarded as a synapomorphy of the Maniraptora. The distal end is curved posteriorly as in Unenlagia comahuensis (possible a synapomorphy uniting both) and differing from the straight condition found in many other maniraptorans (e.g., Deinonychus and Velociraptor) and from the anteriorly curved distal end present in Microvenator, Caudipteryx and the Oviraptoridae (e.g., Oviraptor, Ingenia). The pubic apron is well developed and occupies over half the length of the pubic shaft, similar to Unenlagia comahuensis, Caudipteryx and Deinonychus but differs from the comparatively reduced condition found in Archaeopteryx, Rahonavis, and the oviraptorid Ingenia.
The proximal medial corner of the pubic apron in the new specimen is deflected posteriorly similarly to Unenlagia comahuensis and dromaeosaurids. The pubic boot of the ?Los Barreales form? has a well developed posterior projection (common to several maniraptorans) and shows a small anterior projection; the latter is the main difference from Unenlagia comahuensis that lacks any anterior projection. A possible manual ungual was also found at the site and is here tentatively referred to the ?Barreales form?.
The most interesting feature is the presence of two accessory channels at the proximal part, one above the other bellow the main sulcus situated on the lateral surface of the claw. Although this specimen is known from only two bones (three, if the manual ungual is included), their morphology clearly indicate the presence of an Unenlagia-like dinosaur at the Futalognko site. Based on their overall similarity, reinforced by a potential synapomorphy uniting both (the posteriorly oriented distal end of the pubis), the ?Barreales form? is referable to the genus Unenlagia.
However, some discrete anatomical differences, particularly the presence of a small anterior process at the pubic boot, suggests that the Barreales form represents a new species.