Q. Has anyone determined the weight of a creature by the depth of its footprint in a known material?
A. A few people have asked me similar questions. One correspondent mentioned that Alan Turing, the ‘Father of British Computing’, is reported as considering similar ideas in the book, Alan Turing:The Enigma by Andrew Hodges, so you are in good company with these thoughts.
Unfortunately no one seems to have been able to put this idea into practice. I'm not sure why. Perhaps it is difficult to determine the properties of a 'known material' that may be hundreds of millions of years old. Or perhaps the results show that the dinosaurs were much lighter than seems possible in our present gravity so the results were discarded.