Habitat Preferences of Polar Dinosaurs in Maastrichtian Cretaceous Alaska

A Multi-disciplinary Perspective on Habitat Preferences among Dinosaurs in a Cretaceous Arctic Greenhouse World, North Slope, Alaska (Prince Creek Formation: Upper Maastrichtian)

Authors:

Fiorillo et al

Abstract:

The Prince Creek Formation of northern Alaska is the most abundant source of polar dinosaur remains in the world and now corroborating data from this well-studied rock unit allow for making inferences about the paleoecological preferences for these extinct polar animals. The rock unit records high-latitude, alluvial sedimentation and soil formation on a low gradient, muddy coastal plain. Compound and cumulative andic Entisols and Inceptisols formed on levees, point bars, crevasse splays, and along the margins of floodplain lakes, ponds and swamps. Abundant organic matter, carbonaceous root traces, Fe-oxide depletion coatings and zoned peds indicate periodic waterlogging, anoxia and gleying, consistent with a high water table. In contrast, Fe-oxide mottles, ferruginous and manganiferous segregations, bioturbation, and less common illuvial clay coatings indicate recurring oxidation and periodic drying-out of some soils. An integrated reconstruction of pedogenic processes and biota suggests that this ancient Arctic coastal plain was influenced by seasonally fluctuating water table levels and floods, and in distal areas, marine waters. Four of the five bonebeds in this study are from more distal areas, represented by lower delta plain facies, while the fifth bonebed is from a more proximal part of the basin, represented by a somewhat better drained coastal plain facies.

Bonebeds in the distal areas are dominated by Edmontosaurus sp. while the more proximal bonebed is dominated by the remains of the ceratopsian Pachyrhinosaurus perotorum. The distribution of these bonebeds, sedimentological facies, paleosols and biota, suggest that Pachyrhinosaurus may have preferred more upland environments while Edmontosaurus preferred lowland, deltaic environments. This distribution may be the result of physiological adaptation to the pronounced seasonality provided by polar terrestrial ecosystems. In contrast to a preferred habitat distribution of these large herbivores, the large predatory dinosaur, Nanuqsaurus hoglundi seems to have had a more ubiquitous distribution across the landscape.