Open Paleo

Tianzhenosaurus

Pang & Cheng, 1998 TYEN-juhn-o-SOR-us Disputed

From Tianzhen County (Shanxi Province, China, where the holotype was found) and Greek 'sauros' (lizard); meaning 'Tianzhen lizard'.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Tianzhenosaurus is a genus of ankylosaurid dinosaurs known from the Late Cretaceous Huiquanpu Formation of Shanxi Province, China. The genus contains two species, T. youngi (the type species) and T. chengi.

Under dispute

The validity of Tianzhenosaurus is contested. Sullivan (1999) treated T. youngi as a junior subjective synonym of the Mongolian ankylosaurid Saichania chulsanensis on overall skull similarity, despite differences in the arrangement of cranial osteoderms, and Arbour and Currie (2015) formalized the synonymy, finding no taxonomically significant differences between the holotype skulls. In 2024, Pang, Li and Guo described a second species, T. chengi, treating Tianzhenosaurus as a valid genus. No broad consensus has been reached.

Diagnosis

  1. Skull low, flat, medium-sized, isosceles triangle shape; skull roof covered with irregular bony tubercles.
  2. Orbit small, surrounded by bony ring; narial opening horizontally elongate; septomaxilla does not separate narial openings.
  3. Occipital condyle narrow, high; not visible in dorsal view; opisthotic extends lateroventrally as curved process.
  4. Mandible deep with convex ventral border; no mandibular ornamentation; tooth crowns with cingula on labial sides, swollen bases, and middle ridge on lingual sides.
  5. Eight fused vertebrae in sacrum (three dorsosacrals, four sacrals, one caudosacral); cervical centrum short amphicoelous; dorsal centrum long amphiplatyan.
  6. Tail club present; scapula rectangular plate-like; femur thick lacking fourth trochanter.

Species (2)

Tianzhenosaurus youngi Pang & Cheng, 1998 Disputed

Type species

Dedicated to the late Professor C. C. Young (Yang Zhongjian), founder of vertebrate paleontology in China, in memory of the 100th anniversary of Young's birth, per Pang and Cheng (1998).

Holotype
HBV-10001 , Geoscience Museum, Shijiazhuang University of Economics
Material
Nearly complete skull.
Horizon
upper Huiquanpu Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Kangdailiang near Zhaojiagou Village, Shanxi, China

Synonyms

  • Shanxia tianzhenensis junior subjective

    Per Arbour and Currie (2015), no features distinguish Shanxia from Tianzhenosaurus; both from the same formation with similar squamosal horn morphology, and Tianzhenosaurus youngi has nomenclatural priority by date of publication (1 June vs 15 June 1998).

Tianzhenosaurus chengi Pang et al., 2024

Honors Cheng Zhengwu, researcher in paleontology and stratigraphy at the Institute of Geology, Chinese Academy of Geological Sciences, in recognition of contributions to the discovery, excavation, and preparation of the Tianzhen dinosaur fossils, per Pang, Li and Guo (2024).

Holotype
HBV-10004 , Geoscience Museum, Shijiazhuang University of Economics
Material
Basically complete skull.
Horizon
upper Huiquanpu Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Kangdailiang, Zhaojiagou Township, Shanxi, China

References

  1. Pang, Q.; Cheng, Z. (1998). A new ankylosaur of the late Cretaceous from Tianzhen, Shanxi. Progress in Natural Science.

    Original describing paper for Tianzhenosaurus youngi.

    pang1998a
  2. Sullivan, R. M. (1999). Nodocephalosaurus kirtlandensis, gen. et sp. nov., a new ankylosaurid dinosaur (Ornithischia: Ankylosauria) from the Upper Cretaceous Kirtland Formation (upper Campanian), San Juan Basin, New Mexico. Journal of Vertebrate Paleontology 19(1): 126-139. Informa UK Limited. doi:10.1080/02724634.1999.10011128

    Treats T. youngi as a junior subjective synonym of Saichania chulsanensis on the basis of overall skull similarity, despite differences in cranial osteoderm arrangement.

    sullivan1999a
  3. Arbour, V. M.; Currie, P. J. (2015). Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology 14(5): 385-444. Informa UK Limited. doi:10.1080/14772019.2015.1059985

    Formalizes T. youngi and Shanxia tianzhenensis as junior subjective synonyms of Saichania chulsanensis, finding no taxonomically significant differences between the holotype skulls.

    arbour2015a
  4. Pang, Q.; Li, Z.; Guo, Z. (2024). A new species of ankylosaurian dinosaur—Tianzhenosaurus chengi sp. nov., from the Late Cretaceous of Tianzhen County, Shanxi Province, China. Journal of Hebei GEO University (6): 41-73. doi:10.13937/j.cnki.hbdzdxxb.2024.06.006

    Describes T. chengi as a second species, treating Tianzhenosaurus as a valid genus rather than a junior synonym of Saichania.

    pang2024a