Description and Classification

Suzhousaurus was a fairly large therizinosaur, estimated to be around 6 to 6.5 meters (20 to 21 feet) long and weighing over a ton, possibly around 1.3 metric tons (1.4 short tons). Like other therizinosaurs, it would have had a bulky body, a long neck supporting a small head, and strong arms ending in long, sharp claws. Although direct evidence of feathers has not been found for Suzhousaurus itself, its close relatives like Beipiaosaurus had feathers, so it is very likely that Suzhousaurus was also feathered.

Suzhousaurus belongs to the group Therizinosauria, a strange branch of theropod dinosaurs that evolved to eat plants instead of meat. Within this group, it is considered an early or “basal” member of the family Therizinosauridae, or a closely related advanced therizinosauroid. This means it was more advanced than very early forms like Falcarius but possibly not as specialized as later giants like Therizinosaurus. It shares similarities with other Asian therizinosaurs such as Alxasaurus and Nanshiungosaurus.

Distinguishing Features

Suzhousaurus can be identified by several features of its skeleton, particularly its arm and hip bones:

• It was one of the largest known early therizinosaurs from its time period.
• Its humerus (upper arm bone) was very robust, with a large, well-developed crest for muscle attachment (the deltopectoral crest).
• The bones of its pelvis (hip area) were large and strongly built, with the pubis (a forward-pointing hip bone) being shorter than the ischium (a backward-pointing hip bone).
• Unlike some other dinosaurs, the main bones of its pelvis (ilium, ischium, and pubis) were not fused together in the adult specimens found so far, which is an interesting characteristic.

Paleoenvironment and Diet

Suzhousaurus lived in what is now northwestern China during the Early Cretaceous period. The rocks where its fossils were found, part of the Xinminpu Group, suggest an environment with rivers and lakes. The climate was likely semi-arid with distinct wet and dry seasons. This area supported a diverse range of dinosaurs. Other dinosaurs found in or near the same rock layers include the ornithopod Equijubus, the early horned dinosaur Auroraceratops, the ornithomimosaur Beishanlong, and the early tyrannosaur Xiongguanlong. Sauropods and other theropods also shared this habitat.

Like all known therizinosaurs, Suzhousaurus was an herbivore. Its long neck would have helped it reach vegetation higher off the ground, and its strong arms and long claws were likely used to pull branches towards its mouth or for defense. While its skull and teeth haven’t been discovered, scientists infer from its relatives that it had a small head with teeth suited for stripping leaves and other plant material.

Significance and Ongoing Research

The discovery of Suzhousaurus is important because it helps paleontologists understand the early evolution and spread of therizinosaurs, a unique group of plant-eating theropods. It provides valuable information about the diversity of dinosaurs in Early Cretaceous Asia and highlights how some predatory dinosaurs adapted to a completely different diet and lifestyle. Suzhousaurus stands out due to its relatively large size among early therizinosaurs.

Ongoing research on Suzhousaurus and its relatives focuses on clarifying its exact position within the therizinosaur family tree and understanding the evolutionary steps that led to the highly specialized features of later therizinosaurs like Therizinosaurus. The discovery of more complete skeletons, especially a skull, hands, and feet, would greatly improve our knowledge of its anatomy and how it lived. Further study of the Xinminpu Group ecosystem will also help paint a clearer picture of the world Suzhousaurus inhabited.