Zhejiangosaurus (/ˌZHE-jiang-o-SAU-rus/; "Zhejiang lizard") is an extinct genus of herbivorous ankylosaurian dinosaur from the Late Cretaceous period (Cenomanian stage), living approximately 100.5 to 93.9 million years ago. Its fossils were discovered in the Zhejiang Province of China, and were first described by Lü Junchang et al. in 2007. The genus name "Zhejiangosaurus" directly references the location where the fossils were found.

Description and Classification:

Zhejiangosaurus was a medium-sized ankylosaur, estimated to be around 4.5 meters (15 feet) in length and weighing around 1.4 metric tons (3,000 pounds). Like all nodosaurids, it lacked the iconic tail club characteristic of many other ankylosaurs. However, it possessed several defensive adaptations, including bony armor plates embedded in its skin and osteoderms (bony scutes) running along its back and sides. Its skull was small and low-slung, with small teeth adapted for processing tough vegetation.

Zhejiangosaurus is classified within the Nodosauridae family, a subgroup of ankylosaurs known for lacking tail clubs. However, its exact position within the Nodosauridae family is debated due to the limited fossil material available. Some studies suggest it may belong to a more basal position within the Nodosauridae, while others propose a closer relationship to specific nodosaurid subfamilies.

Distinguishing Features:

One of the most striking features of Zhejiangosaurus is the absence of a tail club, a defining characteristic for most other ankylosaurs. Additionally, its skull is relatively small and lacks the elaborate ornamentation seen in some other ankylosaurs. However, the presence of bony armor plates and osteoderms confirms its affiliation with the armored dinosaur group.

Paleoenvironment and Diet:

The Late Cretaceous environment of Zhejiang Province, where Zhejiangosaurus fossils were found, likely consisted of diverse ecosystems with lush vegetation. It likely coexisted with other dinosaurs, including herbivores like sauropods, ornithopods, and carnivorous theropods. As a herbivore, Zhejiangosaurus likely fed on ferns, cycads, and conifers, using its beak and small teeth to shred tough vegetation.

Significance and Ongoing Research:

The discovery of Zhejiangosaurus provides valuable insights into the diversity and evolution of nodosaurid ankylosaurs. Its lack of a tail club and specific anatomical features contribute to our understanding of the variations within the Nodosauridae family. Additionally, the presence of Zhejiangosaurus in China sheds light on the geographic distribution of ankylosaurs during the Late Cretaceous period.

Further research on existing fossil material and the potential discovery of new specimens are crucial for a more comprehensive understanding of Zhejiangosaurus anatomy, its exact placement within the Nodosauridae family, and its ecological role in the Late Cretaceous ecosystem. With additional discoveries, paleontologists may be able to refine our understanding of its unique characteristics and evolutionary significance within the Ankylosauria group.

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