DESCRIPTION OF TWO PARTIAL TROODON BRAINCASES FROM THE PRINCE CREEK FORMATION (UPPER CRETACEOUS), NORTH SLOPE ALASKA

Two partial theropod braincases recovered from the Upper Cretaceous Prince Creek Formation confirm the presence of Troodon formosus in Alaska. Characters that distinguish one specimen as Troodon formosus include; a very strongly developed sagittal crest on fused parietals, details of pneumatic spaces within the skull bones, and the size and location of the nervous and venous foramina. The second specimen has the distinct lateral depression diagnostic of a troodontid braincase. The recovery of these specimens, coupled with the absence of non-dental material from other small theropod taxa. in these deposits, is significant. It corroborates the conclusion based on dental remains that T. formosus was the most abundant theropod in northern Alaska, thus supporting the model of the adaptability of this taxon to the highly seasonal, low-light conditions that existed in the region during the Late Cretaceous.