"The straight track surely cannot be the NOSE GEAR"
"it cannot be anything else. i can guarantee you from personal experience that it is perfectly possible for a tricycle airplane to skid laterally and leave that type of assymmetrical marks" By gianmarko
Well, assymmetrical marks can be most of the times if you want, but if you have the position of the main gear at every moment, you will ALWAYS know where the nose gear is, unless it is spread off. Actually, if the aircraft would be a lot shorter those relative marks could be possible.
But really, you could deduce at every point which is the possible position of the nose gear (regardless its elevation). I have made a drawing but don't know how to post it.
A possibility would be the last part of the aircraft body, after the main gear. It seems much easier to have created those marks.