Liaoningosaurus 

Genus: Liaoningosaurus Xu, Wang, & You, 2001

Classification: Dinosauria - Ornithischia - Thyreophora - Ankylosauria - Nodosauridae 

Etymology: Generic name refers to Liaoning Province.

Synonyms: none 

Type species: L. paradoxus Xu, Wang, & You, 2001 

Other Species: none 

Diagnosis: as for type species 

Species: Liaoningosaurus paradoxus Xu, Wang, & You, 2001

Etymology: specific name refers to the surprising characteristics of this animal.

Synonyms: none 

Holotype: IVPP V12560, a nearly complete skeleton.

Referred Specimens: none 

Time: Lower Cretaceous.

Horizon: Yixian Formation.

Location: WangJiagou, Yixian, Liaoning Province, China.

Total length: 34 cm (juvenile individual), 2-3 m (adult individual).

Mass: ? 

Diagnosis: An ankylosaurian that differs in having: shell-like ventral armour, trapezoidal sternum with slender and distally pointed posterolateral process and short medial articular margin, and pes more than twice as long as manus (Xu, Wang, & You, 2001). 

Comments: Juvenile ankylosaur specimens are very rare. Liaoningosaurus paradoxus based on a beautifully preserved juvenile ankylosaur specimen from the famous Yixian Formation of Liaoning, China. Liaoningosaurus has a large bony plate (somewhat shell-like) shielding the abdomen. This discovery represents the first record of such a structure among dinosaurs. Although it has a number of distinct

features seen in the family Ankylosauridae, a cladistic analysis placed Liaoningosaurus in the sister-family Nodosauridae. The ‘intermediate’ status of this taxon between the two ankylosaur families further supports the monophyly of Ankylosauria. This finding also documents the smallest known ankylosaur specimen and first complete nodosaurid specimen from Asia (Xu, Wang, & You, 2001). 

IVPP V12560 represents a juvenile individual, as indicated by the unfused centra and neural arches of vertebrae. It is less than 34 cm in length and represents the smallest ankylosaur specimen reported to

date (Xu, Wang, & You, 2001).

Liaoningosaurus is unique among ankylosaurs in displaying a large, ventral abdominal plate. Ankylosaurs show evidence of some ventral dermal armour; however, this is, in all other known examples

(such as Minmi), restricted to small unfused elements that do not form a large plate or shield-like structure (Xu, Wang, & You, 2001). 

Illustrations:

Liaoningosaurus paradoxus (IVPP V12560, holotype). a photograph, b line-drawing of the holotype. Abbreviations: cu clawlike ungual, ftr fourth trochanter, la left astragalus, lc left calcanium, lf left fibula, lh left humerus, lic left ischium, lil left ilium, lm left manus, lr left radius, ls left sternum, lt left tibia, ltr lesser trochanter, lu left ulna, lvp large ventral plate, m maxilla, md mandible, pl plate, pm premaxilla, pmt premaxillary teeth, q quadrate, rp right pes, rs right scapula, vp vertical plate. Scalenbar = 4 cm (modified from Xu, Wang, & You, 2001).

 

Liaoningosaurus paradoxus classification (modified from Xu, Wang, & You, 2001).

 

References:

Xu X., Wang X., & You H., 2001. A juvenile ankylosaur from China . Naturwissenschaften, 88: 297-300.