Er... why? The taxa around the base of Avialae seem to be okay runners and
okay climbers (Archaeopteryx, Rahonavis, Microraptor, Jinfengopteryx, Mei).
Okay runners, yes. Okay climbers... hmm... for bird standards, yes...
Elongated maxillae
I don't know about this. Jinfengopteryx and Mei have shorter maxillae than
Archaeopteryx and Confuciusornis.
Wow! I've completely missed this so far.
At any rate, this taxon probably lived sometime in the late Triassic or earliest Jurassic.
[...] I say Middle Jurassic, where we have taxa slightly less derived than Archaeopteryx (Epidendrosaurus), and basal paravians (Pedopenna).
I do not advocate the use of salamanders in biostratigraphy.