But within the recent fossil record?
How long ago they were is kind of tough to tell, we date the fossils by the strata we find them in but we date the strata by the fossils we find in that strata. Which means that any of the fossils found would be assumed to be a certain age because "everybody know" that they died out millions of years ago. See "coelacanth" for an example.
In any case that something like that existed and that there are creatures that have survived mostly unchanged from that era means that it is possible.