A lot of manoeuvring in birds and bats is done through wing tip deflection, with the tail being used more often in a role similar to that of flaps (trim and lift control). There are exceptions of course, here you can see the tail being used sometimes to deal with a cross-wind:
View: https://www.youtube.com/watch?v=iJff3J_9jVs
Overall though tails are flat (i.e. oriented like a horizontal stabiliser) and integrated into the trailing edge of the wing. So, they'd be classified as tailless design with some polymorphic abilities.
It is worth noting that long tailed versions of birds, bats, and pterosaurs are all well documented, but they were eventually replaced by tailless lineages.
Not directly comparable to aircraft, but I wouldn't be surprised if there isn't a reason for this that also applies to some types of aircraft in the future. Look at the amount of weight the active controls the Boeing Spanloaders would have required in the 1970s, now look at the weight of modern computers and the ability to do things like have distributed airflow sensors... there are a lot of technological limitations against distributed lift designs which are increasingly being overcome.
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