Description of two partialTroodonbraincases from the Prince Creek Formation (Upper Cretaceous), North Slope Alaska

Dinosaur-Bearing Hyperconcentrated Flows of Cretaceous Arctic Alaska: Recurring Catastrophic Event Beds on a Distal Paleopolar Coastal Plain

“…Comment on "A new Arctic hadrosaurid from the Prince Creek Formation (lower Maastrichtian) of northern Alaska" by Hirotsugu Mori, Patrick S. Druckenmiller, and Gregory M. Erickson ANTHONY R. FIORILLO Recently Mori et al (2016) published a paper describing a new taxon of hadrosaurid dinosaur from the Upper Cretaceous Prince Creek Formation of the North Slope Alaska, a rock unit that has recently proven to be a productive source of scientific insights into the workings of an ancient Arctic terrestrial ecosystem (Fiorillo and Gangloff 2001;Gangloff et al 2005;Fiorillo et al 2009Fiorillo et al , 2010Gangloff and Fiorillo 2010;Flaig et al 2011Flaig et al , 2013Flaig et al , 2014Tykoski 2012, 2014). Although thorough testing of the systematics of this proposed taxon will occur over the next few years, one statement in the Mori et al (2016) paper warrants comment now.…”

A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada

“…Since the discovery of Troodon formosus, named on the basis of an isolated tooth from the Judith River Formation (Leidy 1856), only four species have been formally named based on material recovered from North America: T. formosus (Judith River Formation, Montana), Stenonychosaurus inequalis (Dinosaur Park Formation, Alberta), Pectinodon bakkeri (Lance Formation, Wyoming) and Talos sampsoni (Kaiparowits Formation, Utah). Little skeletal material has been described, and skull material is particularly rare (Carpenter 1982;Fiorillo et al 2009;Makovicky and Norell 2004;Russell 1969;Zanno et al 2011), hindering assessments for taxonomic diversity in the group. Despite this, isolated troodontid teeth are relatively common through the Campanian and Maastrichtian of western North America (Cullen and Evans 2016;Larson et al 2016;Larson and Currie 2013).…”

“…Historically, the genus Troodon has been reported to occur throughout the Campanian and Maastrichtian, and across most of western North America , based on referrals of isolated teeth and the few, and generally fragmentary, available fossils (Zanno et al 2011). More recently, some researchers have recognized T. formosus as a form taxon based on potentially non-diagnostic tooth morphology, and suggested that the taxon may contain multiple species or genera (Fiorillo et al 2008(Fiorillo et al , 2009). Zanno et al (2011) noted morphological variation in materials previously referred to this taxon, and hypothesized that the diversity of Late Cretaceous troodontids in North…”

“…Larson and Currie 2013). Previous reports include two troodontid braincases referred to Troodon formosus from the Prince Creek Formation of Alaska (Fiorillo 2008;Fiorillo et al 2009), and a perinate dentary and basioccipital from the Lance Formation (Carpenter 1982). Troodontid cranial material has also been recovered from the Horsethief Member of the Horseshoe Canyon Formation of Alberta (Eberth et al 2013), which is now classified as early Maastrichtian in age (Gradstein et al 2012).…”

“…Eberth et al (2013) listed two undescribed troodontid frontals recovered from this unit, which represent the only reported frontals of this clade from the Maastrichtian of North America. Together with the previously described dentary (Currie 1987a), these constitute all of the nondental troodontid remains from the formation, and some of the only non-dental troodontid remains from the Maaastrichtian of North America (Carpenter 1982;Fiorillo et al 2009). …”