Tim Williams wrote-
(2) Long tails (by avian standards) persisted beyond the Late Jurassic, and are even kept by at least one Late Cretaceous bird: _Rahonavis_. This tells me that some avian lineages were in no hurry to shorten the tail, meaning that there was an advantage in retaining a long tail - such as for their *particular* aerial locomotor style.
(And, actually, _Archaeopteryx_' tail is rather reduced compared to other theropods of the time.)
But not compared to some other later theropods that (based on most current analyses) are more distantly related to modern birds - including oviraptorosaurs and therizinosaurs. Late Jurassic oviraptoriforms may have had shorter tails than _Archaeopteryx_ - we just don't have enough material from these critters to know their overall proportions.