Yi qi, which has membranous wings—a flight apparatus that was previously unknown among theropods but that is used by both the pterosaur and bat lineages6. This observation was not universally accepted7. Here we describe a newly identified scansoriopterygid —which we name Ambopteryx longibrachium, gen. et sp. nov.—from the Upper Jurassic period. This specimen provides support for the widespread existence of membranous wings and the styliform element in the ScansoriopterygidaeThe scansoriopterygids (including Ambopteryx) are members of basal Paraves. With their wing skin membrane and longest outermost finger, they are a candidate transitional between pterosaur and later Paraves. They fit right into the pterosaur to bird theory.
On the other hand, there is zero evidence of membrane wings in any claimed dinosaur ancestor. And also, scansoriopterygids have the outermost digit as the longest, which is not found in any claimed dinosaur ancestor.
For details about Yi qi see here:
http://pterosaurnet.blogspot.com/2015/05/another-scansoriopterygid.html
For details about Scansoriopteryx see here:
https://pterosaurnet.blogspot.com/2014/07/scansoriopteryx.html
https://m.phys.org/news/2019-05-jurassic-non-avian-theropod-dinosaur-flight.html
