Dinosaurs on the North Slope, Alaska: High Latitude, Latest Cretaceous Environments

Abstract

Abundant skeletal remains demonstrate that lambeosaurine hadrosaurid, tyrannosaurid, and troodontid dinosaurs lived on the Alaskan North Slope during late Campanian-early Maestrichtian time (about 66 to 76 million years ago) in a deltaic environment dominated by herbaceous vegetation. The high ground terrestrial plant community was a mild- to cold-temperate forest composed of coniferous and broad leaf trees. The high paleolatitude (about 70 degrees to 85 degrees North) implies extreme seasonal variation in solar insolation, temperature, and herbivore food supply. Great distances of migration to contemporaneous evergreen floras and the presence of both juvenile and adult hadrosaurs suggest that they remained at high latitudes year-round. This challenges the hypothesis that short-term periods of darkness and temperature decrease resulting from a bolide impact caused dinosaurian extinction.

Fossils and fossil climate: the case for equable continental interiors in the Eocene

“…It is also possible that some dinosaurs migrated long distances to take advantage of seasonally available resources in high latitudes (Brouwers et al 1987), thus giving no information on year-round conditions.…”

A pterosaur manus track from Denali National Park, Alaska Range, Alaska, United States

“…Recently the skeletons of large pterosaurs have been shown to have increased appendicular pneumaticity and this may have aided in thermoregulation (Claessens et al, 2009). The large size of the DENA pterosaur, as a function of thermoregulation capabilities, is expected given the presumed strong seasonality of this ancient northern environment (Brouwers et al, 1987;Parrish et al, 1987;Gangloff, 2000, 2001;Fiorillo, 2004Fiorillo, , 2008aFiorillo, , 2008b.…”

“…Significant effort has been spent examining the vertebrate fossil record of far northern Alaska (Brouwers et al, 1987;Parrish et al, 1987;Nelms, 1989;Clemens and Nelms, 1993;Clemens, 1994;Gangloff, 1998;Gangloff, 2000, 2001;Fiorillo, 2004Fiorillo, , 2006Fiorillo, , 2008bFiorillo et al, 2005;Gangloff et al, 2005). The Upper Cretaceous rocks of this region contain the densest concentrations of fossil vertebrates of any high latitude location in the northern or southern hemisphere (Rich et al, 2002).…”

Crayfish burrows from the latest Cretaceous lower Cantwell Formation (Denali National Park, Alaska): Their morphology and paleoclimatic significance

“…Further, coupled with the Late Cretaceous fossil vertebrate remains found throughout Alaska, this was a widespread and rich terrestrial polar ecosystem (Brouwers et al, 1987;Parrish et al, 1987;Clemens and Nelms, 1993;Gangloff, 1995Gangloff, , 1998Gangloff, 2000, 2001;Fiorillo and Parrish, 2004;Gangloff et al, 2005;Fiorillo et al, 2009aFiorillo et al, ,b, 2011Fiorillo et al, , 2014aGangloff and Fiorillo, 2010;Fiorillo and Adams, 2012;Tykoski, 2012, 2014).…”