Motion studies with large mammals and dinosaurs

Within a cooperation of the University of Bochum (Ruhr-Universitaet, Anat. Inst., Funktionelle Morphologie), the F.I.B.U.S. research institute, and the Krefeld zoo a motion study at elephants has been performed to provide information on efficiency of locomotion of heavy animals like dinosaurs or elephants.

While popular movies like the well known "Jurassic Park" movie suggest that exact data on those primeval animals already exist, different research teams come to completely different conclusions about important data like mass and maximum speed of the dinosaurs. For the Brachiosaurus the maximum body mass ranges from 40 to 70 tons, according to the researchers. Looking at the maximum speed it is even worse: while one research team claims very fast running speed of 61 km/h for the Stegosaurus, the other team came to a maximum of only 7 km/h.

It is evident that we have to learn more about live conditions and efficiency of dinosaurs. It can be expected that we obtain interesting information on handling of large body mass from this investigation. As real live experiments with dinosaurs are difficult to perform nowadays, it was decided to use elephants for the experiments. It is assumed that elefants with a weight of several tons can at least give some information on the motion conditions of large dinosaurs.

Due to the kind cooperation of the Krefeld zoo and especially with the help of elephant trainer W. Nehring it was possible to record motion sequences of the walking and running elephants.

The sequences were recorded directly into the memory of the picCOLOR image analysis system to provide high spatial resolution. All joints at the legs of the elephant were marked by round white stickers. During the post analysis the sticker position has been tracked with subpixel accuracy. Vectorized joint positions were output to file for analysis of joint acceleration.

First results show that the former theories that elefants use their legs like passive pendulums to save energy are not correct. Instead they use a very simple trick by lifting their hips for acceleration of the pendulum motion. The analysis shows an increased acceleration of about two times the earth acceleration for the leg after loosing contact of the ground from the rear position. According to this result it is evident that the maximum speed estimate has to be newly formulated. The very low speeds, postulated by various research teams, can't be valid anymore.

More data at different running speed of the elephant will be analysed in the future to obtain more accurate and reliable results. Additionally the touch down of the foot will be analysed at high accuracy. By analyzing the touch down case of the foot we can learn a lot about how the elephant handles deceleration and damping of his large body mass.