Some, though given the timescale, and the assumptions that not many birds were robust enough for remains to be preserved before decomposition and not many birds lived in the kinds of environments that favored fossilization, there aren’t as many as there are for, say, reptile to mammal. Here’s an initial list. One last aside: be careful with demanding transitionals, as it becomes all to easy to demand “the one in between those”, on and on recursively. It’s dishonest to keep raising the bar. The existence of even some transitional fossils is enough to show that such things can and do exist. The notion that there would be animals similar to both a predecessor and an antecedent, and yet related to and generationally independent of both is absurd:
# Lisboasaurus estesi and other “troodontid dinosaur-birds” — a bird-like reptile with very bird-like teeth (that is, teeth very like those of early toothed birds [modern birds have no teeth]). May not have been a direct ancestor; may have been a “cousin” of the birds instead.
# Protoavis — this is a highly controversial fossil that may or may not be an extremely early bird. Not enough of the fossil was recovered to determine if it is definitely related to the birds, or not. I mention it in case people have heard about it recently.
# Archeopteryx — reptilian vertebrae, pelvis, tail, skull, teeth, digits, claws, sternum. Avian furcula (wishbone, for attachment of flight muscles), forelimbs, and lift-producing flight feathers. Archeopteryx could probably fly from tree to tree, but couldn’t take off from the ground, since it lacked a keeled breastbone (for attachment of large flight muscles) and had a weak shoulder (relative to modern birds). Not currently considered transitional, but a good example of the changes in morphology along the way; more of a dead-end.
# “Chinese bird” [I don’t know what name was given to this fossil] — A fossil dating from 10-15 million years after Archeopteryx. Bird-like claws on the toes, flight-specialized shoulders, fair-sized sternal keel (modern birds usually have large sternal keel); also has reptilian stomach ribs, reptilian unfused hand bones, & reptilian pelvis. This bird has a fused tail (”pygostyle”), but I don’t know how long it was, or if it was all fused or just part of it was fused.
# “Las Hoyas bird” [I don’t know what name was given to this fossil] — This fossil dates from 20-30 m.y. after Archeopteryx. It still has reptilian pelvis & legs, with bird-like shoulder. Tail is medium-length with a fused tip (Archeopteryx had long, unfused tail; modern birds have short, fused tail). Fossil down feather was found with the Las Hoyas bird.
# Toothed Cretaceous birds, e.g. Hesperornis and Ichthyornis. Skeleton further modified for flight (fusion of pelvis bones, fusion of hand bones, short & fused tail). Still had true socketed teeth, which are missing in modern birds.
And that’s just pieces of the bird line. Other animals are far better represented. There are hundreds of so-called transitional fossils.
According to creationists zero.
That's because according to them, every time a critter is found with features and age mid-way between known critters creationists blandly insist that the new critter doesn't fill the gap, but actually creates two new gaps on either side.