Is it just me or are the fossil marks really difficult to see? They blend in with the ground almost perfectly. Thus I keep falling into pitfalls and I can't find many fossils, which is worse because Hopper asked me to get a certain fossil... Any help on finding them?

Walk slow, and I find them when I am watering my many flowers.  

I've even found fossils in behind buildings, so don't forget to look there. PatMcNJ is right about walking slowly when hunting for fossils because they tend to hide in the flower beds and watering makes it easier to find them in my opinion.