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Polar dinosaurs on parade: a review of dinosaur migration.
Cretaceous polar dinosaur faunas were taxonomically diverse, which suggests varied strategies for coping with the climatic stress of high latitudes. Some polar dinosaurs, particularly larger taxa such as the duckbill Edmontosaurus Lambe, 1917, were biomechanically and energetically capable of migrating over long distances, up to 2600 km. However, current evidence strongly suggests many polar dinosaurs (including sauropods, large and small theropods, and ankylosaurs of New Zealand) overwintered in preference to migration. Certain groups also appear more predisposed to overwintering based on their physical inability (related to biomechanics, natural history, or absolute size) to migrate, such as ankylosaurs and many small taxa, including hypsilophodontids and troodontids. Low nutrient subsistence is found to be the best overwintering method overall, although the likelihood that other taxa employed alternative means remains plausible. Despite wide distribution of some genera, species level identification is required to assess the applicability of such distributions to migration distances. Presently, such resolution is not available or contradicts the migration hypothesis.
Size dependent anatomy of migration. Although dinosaurs lacked the specific efficient mechanisms in the mammalian limb, they may have benefited energetically by simply being larger. A longer stride length and more upright limb posture in a 13 m long Edmontosaurus, in comparison with the caribou, meant it could cover the same distance while potentially using less energy relative to body mass.