|Unenlagia comahuensis ©Nobu Tamura|
I want to do something crazy this week. I am going to discuss 2 (3 if we include a tentative name) dinosaurs that may or may not be the same dinosaur. "Like that hasn't happened before" some of you are probably thinking. In the search for a dinosaur for the week during my granola bar feast at lunch, I found a dinosaur name that led to a completely different dinosaur that has been mentioned as a potential junior synonym of a longer known dinosaur. All 3 dinosaurs have been questioned, placed in a subfamily known as Unenlagiinae, and have been described or redescribed a few times. Incidentally, or coincidentally as the case may be, all 3 are small theropods consisting of fragmentary skeletal evidence. Technically the first name, Araucanoraptor argentinus, was only a tentative name attached to the remains that were later named Neuquenraptor argentinus (Thief of Neuquen, Argentina) officially by Fernando Novas (Bernardino Rivadavia Natural Sciences Museum) and Diego Pol (Ohio State University) in 2005. The remains had been unearthed in 1995, the tentative name applied in 1997, and a familial relationship with the Troodontidae considered in 1999. In 2005, shortly after the remains were described and named as holotype of the species, a paper announcing the earliest dromaeosaur, Buitreraptor, from South America was published that suggested the two taxa Neuquenraptor and Unenlagia were similar in time and geography and may represent the same species but are too fragmentary to certainly tell apart. Oddly enough, La Buitrera, where Buitreraptor's remains were unearthed, is in Neuquen province. This matter appears to have not been definitively resolved as yet.
What about Unenlagia? Unenlagia comahuensis (Half-bird of Comahue) and U. paynemili (Half-bird of Maximilo Paynemil) were named in 1997 an 2004 respectively. The animals are both very similar to Neuquenraptor in that they appear to represent very fragmentary dromaeosaurid theropods. Initially Unenlagia was considered by Novas et al. (1997) to be a sister of extant birds, but Norell and Mackovicky (1999) disputed this claim and placed Unenlagia into the Dromaeosauridae where it rests today. I hope to dig up more on these two dinosaurs during this coming week, including some comparisons of the photographed material and maybe, if we are lucky, some commentary from some of the paleontologists involved.
Makovicky, P.J., Apesteguıa, S., and Agnolın, F.A. (2005). The earliest dromaeosaurid theropod from South America. Nature 437: 13.
Norell, M.A.; Makovicky, P.J. (1999). Important features of the dromaeosaur skeleton II: information from newly collected specimens of Velociraptor mongoliensis. American Museum Novitates 3282: 1–45.
Novas, F.E., Cladera, G. & Puerta, P. (1997) New theropods from the Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology 16, 56A
Novas, F.E.; Pol, D. (2005). New Evidence on Deinonychosaurian Dinosaurs from the Late Cretaceous of Patagonia. Nature 433 (7028): 858−861