See, the good ol' T of E was... um, invented? Discovered?  Whatever
the term is, it was come up with by a couple of scientists (Darwin,
and another fellow whose name eludes me) studying animal distribution
and morphology.  Then someone said, Hey, if this theory is true, then
shouldn't comparative anatomy show great similarities between different
creatures that we think are closely related?  And it was so.  And
somebody else said, Hey, if this theory is true, then shouldn't these
fossils look like they should show transitions between different life
forms?  And it was so.  And, for that matter, with modern science, 
we've done that with the genetic codes of various living things and
found out, yep, these things that we've been saying _should_ have
similar chromosomal structures _do_.  I suppose that if the only proof
you accepted was eyewitness accounts, that's not proof... but when one
has a theory, one can make predictions with it, and if the predictions
are true, and do follow from the theory, they are considered evidence
_for_ the theory.

Anyway, the point is, the good ol' T of E was (whatever)ed BEFORE all
this fossil evidence came along... but the fossils acted like the theory
said they should... and so on, and so forth.