What kinds of evidence does the fossil record provide that allows scientists to draw conclusions about life on Earth millions of years ago?

They provide half lives by radio active decay that can tell how old they are and earth also they provide analogous and and homologous structures

The evidence it leaves is what type of environment it was then, how big were the animals, who ate what, and etc. it can draw conclusions of what animals were then and how animals have went through evolution. Scientists are able to make hypothesis and educated guesses on things.