Science literally cannot tell us anything about the past. Science is about testing a hypothesis in a reproducible way. Then you formulate a general theory based on a validated hypothesis. If your hypothesis requires a time machine to test, it cannot be tested (yet).

Science learns us about the observable world. We can only observe the lack of plant fossils at certain depths in the earth's crust. However, we cannot test any hypothesis that the reason we cannot find plants is because the was less CO2 100 million years ago.

"Scientists" are very sloppy today. They should disclaim everything related to history as an untestable hypothesis.

Even the "fact" that dinos roamed the earth is an unproven hypothesis. Although the observable evidence of large bones in fossils seems to support the hypothesis, it can never be tested and thus there will never be a scientific theory that proves the existence of dinos.