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Physiological, Migratorial, Climatological, Geophysical, Survival, and Evolutionary Implications of Cretaceous Polar Dinosaurs
Gregory S. Paul
Journal of Paleontology
Vol. 62, No. 4 (Jul., 1988), pp. 640-652
Published by: Paleontological Society
Stable URL: http://www.jstor.org/stable/1305468
Page Count: 13
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The presence of Late Cretaceous social dinosaurs in polar regions confronted them with winter conditions of extended dark, coolness, breezes, and precipitation that could best be coped with via an endothermic homeothermic physiology of at least the tenrec level. This is true whether the dinosaurs stayed year round in the polar regime--which in North America extended from Alaska south to Montana--or if they migrated away from polar winters. More reptilian physiologies fail to meet the demands of such winters in certain key ways, a point tentatively confirmed by the apparent failure of giant Late Cretaceous phobosuchid crocodilians to dwell north of Montana. Low metabolisms were also insufficient for extended annual migrations away from and towards the poles. It is shown that even high metabolic rate dinosaurs probably remained in their polar habitats year round. The possibility that dinosaurs had avian--mammalian metabolic systems, and may have borne insulation at least seasonally, severely limits their use as polar paleoclimatic and Earth axial tilt indicators. Polar dinosaurs may have been a center of dinosaur evolution. The possible ability of polar dinosaurs to cope with conditions of cool and dark challenges theories that a gradual temperature decline, or a sudden, meteoritic or volcanic induced collapse in temperature and sunlight, destroyed the dinosaurs.
Journal of Paleontology © 1988 Paleontological Society