Liaoningvenator (meaning "Liaoning hunter") is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, L. curriei, named after paleontologist Phillip J. Currie in 2017 by Shen Cai-Zhi and colleagues from an articulated, nearly complete skeleton, one of the most complete troodontid specimens known. Shen and colleagues found indicative traits that placed Liaoningvenator within the Troodontidae. These traits included its numerous, small, and closely packed teeth, as well as the vertebrae towards the end of its tail having shallow grooves in place of neural spines on their top surfaces.
Within the Troodontidae, the closest relative of Liaoningvenator was Eosinopteryx, and it was also closely related to Anchiornis and Xiaotingia; while these have traditionally been placed outside the Troodontidae, the phylogenetic analysis conducted by Shen and colleagues offered evidence supporting the alternative identification of these paravians as troodontids. Compared to its close relatives, however, Liaoningvenator had relatively long legs, in particular the femora. As the fifth troodontid known from geographically and temporally comparable strata, Liaoningvenatorincreases the diversity of Chinese troodontids.
With a total body length (estimated lengths of the skull, neck, trunk, and tail combined) of approximately 69 cm (27 in), Liaoningvenator is a small troodontid.[1]
Liaoningvenator possesses a long, narrow, and triangular skull that measured 9.8 cm (3.9 in) long. At the front of the snout, like Sinovenator and Xixiasaurus, the premaxilla excludes the maxilla from the rim of the nostril. There are three openings on the surface of the maxilla, the premaxillary, maxillary, and antorbital fenestrae. Below, the maxilla forms the secondary palate as in Byronosaurus, Gobivenator, and Xixiasaurus. Uniquely among troodontids, the postorbital bone is slender and radiates into three processes. Like Zanabazar, there is a pneumatic diverticulum in the jugal bone where an air sac was present within the bone; there is also a pneumatic opening on the rear side of the quadrate bone, as in other troodontids.[2] Unlike Sauronithoides, Zanabazar, and Stenonychosaurus, the crest separating the parietal bones does not participate in the border of the supratemporal (upper) temporal fenestra at the back of the skull.[1]
Characteristic of troodontids,[2] Liaoningvenator has a pitted groove on the outer edge of its shallow and triangular lower jaw. The bottom margin of the jaw is slightly convex; in Sinornithoides, it is straight. The dentary and angular bones may have formed a flexible joint within the jaw - that is, an intramandibular joint.[3] Unlike Xiaotingia, the dentary and maxilla terminate at the same position in the jaw. Also like other troodontids (with Sinusonasus being an exception), Liaoningvenator has a number of small, closely spaced teeth, with at least 15 in the upper jaw and 23 in the lower jaw. The teeth towards the rear of the lower jaw are serrated, unlike a number of basal troodontids. The tooth row of the maxilla terminates below the front margin of the antorbital fenestra, whereas it terminates further forward - below the rear of the maxillary fenestra - in Jinfengopteryx.[1]