Speeds of dinosaurs from the Albian-Cenomanian of Patagonia and sauropod stance and gait

Abstract

Estimates of locomotory speeds of small to large-sized Patagonian dinosaurs are pre-sented for the first time. These estimates are inferred from trackways found on fine to coarse-grained brown sandstones located in the lower section of the Candeleros Member of the Rio Limay Formation (Albian-Cenomanian), NeuquCn Province, Argentina. The method used is based on the measurement of the stride length (distance between two suc-cessive prints of the same foot) and of the length of the hindfoot print, which in turn, al-lows us to estimate the height at the hip joint and, therefore, the approximate size of the animal. The hypothesis of dynamic similarity implies that the movements of geometri-cally similar animals, although of different sizes, are dynamically similar only when they move with the same Froude number. The dynamically similar movements (i.e., those with equal Froude number) require equal values of relative stride length (ratio between the stride length and the hip joint height). The relationship between the relative stride length and the Froude number allows us to estimate the speeds of dinosaurs. The dino-saurian ichnofauna studied reveals low speeds that range from 0.5 to 2.6 m s-'. Our analy-ses show that the sauropods responsible for these trackways were either walking very