Along with its contemporary Entelognathus, Qilinyu is an unusual placoderm showing some traits more similar to bony fish, such as dermal jaw bones and lobe-like fins.

It can be characterized by adaptations for a benthic lifestyle, with the mouth and nostrils on the underside of the head, similar to the unrelated antiarch placoderms.

The holotype specimen is the most complete, representing a set of fully articulated head and trunk armor missing only the dentaries (lower jaws).

Fossils of the Xiaxiang fauna were excavated over several trips from 1999 to 2016, and are now stored at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP).

[1] Conodont biostratigraphy has indicated that the fauna was deposited in the later part of the Silurian, specifically the late Ludfordian stage near the end of the Ludlow Epoch.

The chimeric nature of the mythological Qilin is referenced by the combination of placoderm-like and osteichthyan-like traits apparent in Qilinyu.

The rostrum projects forwards while the jaws and nostrils are completely recessed under the head, akin to a skate or sturgeon.

[1] Another difference from bony fish is that the three external jaw bones of Qilinyu are completely toothless and have an L-shaped cross-section.

Qilinyu also lacks infradentaries (bones at the lower edge of the jaw) or gular plates (throat armor), in contrast to Entelognathus and bony fish.

[1] Qilinyu differs from Bianchengichthys in possessing a longer rostrum while lacking dentary denticles, a lateral line branch on the postmarginal, and a preorbital plate on either side of the rostral.

[2] Qilinyu, Entelognathus, and bony fish all have three distinctive non-jaw bones flanking the upper jaw: the lacrimal, jugal, and opercular.

At its front terminus it sharply bends down as the infraorbital line groove, which passes behind the eye along the anterior postorbital and jugal.

An additional lateral line groove (the posterior pitline) branches inwards from the anterior paranuchal to the central plate.

The rear edge of the skull's posterior paranuchal plate fits into this groove, a form of articulation similar to that of antiarchs, where it is called a 'reverse ginglymoid' joint.

Unlike antiarchs, the underside of the posterior paranuchal plate also has a shallow depression defined by a shelf-like ridge.

[1][4] Maximum parsimony and Bayesian phylogenetic analyses in the original description by Zhu et al. (2016) placed Q. rostrata as the sister taxon to a clade containing Entelognathus, Janusiscus, and crown-group gnathostomes (i.e., bony and cartilaginous fishes and their descendants).

[2] Below is a cladogram showing the results of Zhu et al. (2016):[1] Galeaspida Osteostraci Antiarchi Brindabellaspis Romundina Jagorina Gemuendina Petalichthyida Arthrodira Ptyctodontida Qilinyu Entelognathus Janusiscus Chondrichthyes Osteichthyes