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. 2013 Jan 16;8(1):e53873. doi: 10.1371/journal.pone.0053873

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© 2013 Walmsley et al

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.

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The problem definition used to determine the equations of motion that describe the feeding behaviour associated with twisting a prey item. Bottom Left: the range of motion for a crocodile twisting a prey item. Bottom right: the equations used to calculate the Torque generated by a crocodile of mass () as a result of twisting about its own axis with a prey item held in its jaws. Torque is the produce of moment of inertia () about the animals long axis and the angular acceleration () – which is assumed to be constant. Moment of inertial is calculated using mass () and radius (); in our calculations mass is approximated as fifty times the mass of the skull (approx. 40 kg in the M. cataphractus example shown here), while radius is approximated as skull width (approx. 152 mm in M. cataphractus). Initial angular velocity () is zero since in this case the twist is being made from a standing start. denotes the angular displacement of the twist in radians ( or 360 degrees in this case), while denotes the time taken to complete the rotation –0.5 seconds.

Inline graphic — The problem definition used to determine the equations of motion that describe the feeding behaviour associated with twisting a prey item. Bottom Left: the range of motion for a crocodile twisting a prey item. Bottom right: the equations used to calculate the Torque generated by a crocodile of mass () as a result of twisting about its own axis with a prey item held in its jaws. Torque is the produce of moment of inertia () about the animals long axis and the angular acceleration () – which is assumed to be constant. Moment of inertial is calculated using mass () and radius (); in our calculations mass is approximated as fifty times the mass of the skull (approx. 40 kg in the M. cataphractus example shown here), while radius is approximated as skull width (approx. 152 mm in M. cataphractus). Initial angular velocity () is zero since in this case the twist is being made from a standing start. denotes the angular displacement of the twist in radians ( or 360 degrees in this case), while denotes the time taken to complete the rotation –0.5 seconds.