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Pectinodon is a genus of troodontid Theropoda from the end of the Maastrichtian age of the Late Cretaceous period (66 mya). It currently contains a single valid species, Pectinodon bakkeri (sometimes classified as Troodon bakkeri), known only from teeth.
The holotype, UCM 38445, consists of a 6.2 mm long adult tooth. The are three juvenile teeth.
In 1985, Lev Nesov named a second species, Pectinodon asiamericanus, based on specimen CCMGE 49/12176, a tooth from the Khodzhakul Formation of Uzbekistan that dates from the Cenomanian age.L.A. Nesov, 1985, "Novye mlekopitayushchie Mela Kyzylkumov", Vestnik Leningradskogo Universiteta, Geologiia, Geografiia, series 7 17: 8-18 This is today often considered a nomen dubium.A. O. Averianov and H.-D. Sues, 2007, "A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union", Journal of Vertebrate Paleontology 27(1): 87-98
While historically considered synonymous with Troodon or more specifically the species Troodon formosus, Philip Currie and colleagues (1990) noted that the P. bakkeri fossils from the Hell Creek Formation and Lance Formation might belong to different species. In 1991, George Olshevsky assigned the Lance formation fossils to the species Troodon bakkeri.Olshevsky, G. , 1991 A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings 2 196 ppCurrie, P. (2005). "Theropods, including birds." in Currie and Koppelhus (eds). Dinosaur Provincial Park, a spectacular ecosystem revealed, Part Two, Flora and Fauna from the park. Indiana University Press, Bloomington. Pp 367–397. In 2011, Zanno and colleagues reviewed the convoluted history of troodontid classification in Late Cretaceous North America. They followed Longrich (2008) in treating Pectinodon bakkeri as a valid genusN. Longrich, 2008, "A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: implications for the study of dissociated dinosaur remains", Palaeontology 51(4) 983-997 and noted that it is likely the numerous Late Cretaceous specimens currently assigned to Troodon formosus almost certainly represent numerous new species, but that a more thorough review of the specimens is required.
In 2013, Currie and Derek Larson concluded that Pectinodon bakkeri was valid and its teeth could be found both in the Lance Formation and the coeval Hell Creek Formation. Some teeth from the older Campanian Dinosaur Park Formation could not be statistically differentiated from them, likely due to an insufficiently large sample, and were referred to cf. Pectinodon.
Pectinodon
Description
While Pectinodon is only known from teeth, its larger family Troodontidae is known from much more complete specimens. They were small, bird-like feathered bipedal with proportionally large eyes and brains. Like Dromaeosauridae, they possessed a "sickle-claw" on the second toe of each foot. See the Troodontidae article for more information.
Paleobiology
Despite having only teeth to infer behavior for Pectinodon, they are very informative fossils. Several studies have been done on troodontid teeth, shedding light on their behavior and ecology. Their tooth morphology suggests they preferred soft prey items like invertebrates, small vertebrates, or carrion. Their dentition was not as well suited for high-stress feeding as in their cousins the dromaeosaurids and Tyrannosauridae. Tooth morphology also led some researchers to speculate that troodontids were Omnivore.Holtz, T.R., Jr., Brinkman, D.L., and Chandler, C.L. (1998). Denticle mor- phometrics and a possibly omnivorous feeding habit for the theropod dinosaur Troodon. Gaia 15, 159–166. This hypothesis was reaffirmed in a study that used stable isotopes in tooth enamel to reconstruct paleo-ecologies.
See also
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