Description and Classification

Nanningosaurus was a large, plant-eating dinosaur that could walk on both two legs (bipedally) and four legs (quadrupedally). Scientists estimate it grew to be about 7.5 meters (25 feet) long and weighed around 2.5 metric tons (2.8 short tons). As a member of the Hadrosauridae family, often called “duck-billed dinosaurs,” Nanningosaurus would have had a broad, flattened snout, although a complete skull has not yet been found. Like other hadrosaurids, it possessed complex dental batteries—many small teeth packed together—which were highly effective for grinding tough plant material. However, as a hadrosaurine (a subfamily of hadrosaurids), Nanningosaurus would not have had the elaborate hollow crests found on the heads of lambeosaurine hadrosaurs like Parasaurolophus.

Nanningosaurus is classified within the Dinosauria, belonging to the group Ornithischia, and then further into Ornithopoda. Within this group, it is a member of the Hadrosauridae family and the Hadrosaurinae subfamily. It is considered a relatively basal, or early-branching, member of the hadrosaurines, meaning it shared characteristics with earlier forms of these dinosaurs. Its relatives include other hadrosaurines such as Edmontosaurus and Maiasaura.

Distinguishing Features

Paleontologists distinguish Nanningosaurus from other hadrosaurids based on several specific features found in its skeleton, particularly in its hip bones and tail. These include:

• A slender ischial peduncle (the part of the ilium, or upper hip bone, that connects to the ischium, a lower hip bone) that is bent downwards and towards the sides of the body.
• An S-shaped shaft of the ischium.
• A tail (caudal region) composed of approximately 50 vertebrae.
• Slender unguals, which are the bones that would have formed the core of its hoof-like claws on its toes.

Paleoenvironment and Diet

Nanningosaurus lived in what is now the Nalong Basin of Guangxi, China. During the Late Cretaceous, this area was a terrestrial environment, likely featuring rivers, floodplains, and forests with abundant vegetation. The climate was probably warm and humid. The Nalong Formation, where its fossils were found, has yielded remains that suggest a diverse ecosystem. Other types of dinosaurs that lived in southern China during this period included meat-eating tyrannosauroids and bird-like oviraptorosaurs.

As a hadrosaurid, Nanningosaurus was an herbivore. Its powerful jaws and specialized dental batteries were well-suited for processing large quantities of tough plant matter. It likely fed on conifers, cycads, ferns, and early flowering plants, browsing on vegetation at low to medium heights. Its ability to switch between walking on two legs and four legs would have helped it to reach different types of food and move efficiently through its habitat.

Significance and Ongoing Research

The discovery of Nanningosaurus is significant because it adds to our knowledge of hadrosaur diversity in southern China, a region from which fewer dinosaur fossils have been recovered compared to northern China or North America. Its unique features provide valuable information for understanding the early evolution and diversification of the Hadrosaurinae subfamily. The presence of Nanningosaurus helps paleontologists build a more complete picture of Asian dinosaur ecosystems just before the mass extinction event that ended the Cretaceous period.

Ongoing research on Nanningosaurus includes further detailed study of the existing fossil material to better understand its anatomy and its precise relationships to other hadrosaurids. Paleontologists are also hopeful that future expeditions to the Nalong Basin will uncover more complete skeletons, especially skull material, which would provide much more information about its appearance and feeding adaptations. Continued investigation of the Nalong Formation will also help to reconstruct the ancient environment in which Nanningosaurus lived and the other species that shared its world.