Let me see if I can help
Kingsway... first take a look at this entertaining site:
http://volcano.und.edu/vwdocs/vwlessons/lesson s/Pangea/Pangea4.html
You can see that just before the age of the dinosaurs the land mass that would eventually become the various continents of the earth were all closely associated in a mass that geologists have called
Pangea... Over the millions of years the plates upon which all continents rest moved and are still moving. Where they butt against one another a
subduction zone was created. One plate was forcefully moved downward while the other was forced upwards. (This is the cause of the Christmas
tsunami two years ago)... It's also the area where the world's volcano activity is centered. Hence mountains are built and then are eroded away by weather. In doing so, fossils and other artifacts are buried. Sometimes the fossils come to the surface by the erosion activity and sometimes the fossils are found by excavation. So... long winded way of saying the fossil you're discussing was once on top of the earth (when the animal died) was buried, became fossilized and was subsequently covered... in this case very deep... (Written test in 10 minutes, class)...