It does look like teeth on that lower area. On the other pic the lines looked very fine like scratch marks, but this bigger pic rules that out. A squirrel and rat are big enough to eat the fat from over the lip and would have avoided going into the pan. The teeth marks are too small for that anyway. A mouse would more than likely have left a tail print and whisker marks.. so it points to a short tailed vole. There were loads around the area, I saw two running around by our site the previous night. It's a great bit of sign though.