[1] Cruralispennia lived alongside several other species of enantiornitheans, such as Protopteryx, in the Sichakou Basin of the Huajiying Formation, approximately 130.7 million years ago.

Despite being one of the earliest known ornithothoraces, this genus possessed several features of derived enantiornitheans as well as some unusual traits convergent with ornithuromorphs, a group containing modern birds.

The hand is shorter than the humerus and the alular digit is reduced, both features characteristic of advanced enantiornitheans.

The ischium is shorter than the pubis and has an upward pointing process midway down the shaft, similar to that of basal ornithuromorphs.

They are long and wire-like, consisting of a rachis-like structure seemingly formed from the fusion of a bundle of parallel barbs.

[2] Structures believed to be fossilized melanosomes were found in five feather samples from the specimen using scanning electron microscopy.

[4] A sample taken from the crural feathers had eumelanosomes with the shortest aspect ratio, which may have corresponded to dark brown coloration.

High aspect ratios have been known to correlate with glossy or iridescent colors, although without knowing the structure of a feather's keratin layer (which does not fossilize well), no hue can be assigned for certain.

A phylogenetic analysis recovered Cruralispennia as a moderately advanced enantiornithean, more derived than basal members of the clade such as Protopteryx and pengornithids.

However, the presence of a short, plow-shaped pygostyle in IVPP 21711 shows that Cruralispennia had some derived features which were very different from other enantiornitheans.

Cruralispennia seemingly belongs to a previously undiscovered ancient lineage of enantiornitheans which had convergently evolved many ornithuromorph-like features.

In addition, the presence of such a derived genus so early in the Cretaceous is evidence that the family tree of ornithothoraces is older than currently known fossils suggest.

These factors are support for the idea that individuals of Cruralispennia grew quickly, reaching adult size in less than a year.

Although PWFDT feathers were probably too simple to provide any aerodynamic advantage, their narrowness means that they were unlikely to have been an inhibiting factor either.