Experiments are a subset of tests; indeed, the word experiment is defined as a scientific test. So the real question is, what kind of testing do scientists do on fossilized remains to check whether they're the results of evolutionary changes.
One test is to determine roughly how old the remains are. Another is to determine their taxonomy (characteristics shared between organisms). A third is to test to see how similar their DNA is (and yes, even fossils have DNA
; it's apparently possible to recover at least some DNA from fossils that are several million years old). There are probably others as well, but I'm not as knowledgeable about them.
Here's some sources for evidence relating to common descent:http://www.talkorigins.org/faqs/comdesc/http://evoled.dbs.umt.edu/lessons/evidence.htmhttp://ncse.com/book/export/html/11771