Qianzhousaurus

Its Greatest Feature: A Long, Slender “Pinocchio”-like Snout

The most defining characteristic of this dinosaur is its extremely elongated snout.
Due to its unique shape, it evokes the image of the fairytale protagonist whose nose grew when he lied, hence the name “Pinocchio rex.”

A Snout Reaching 90 cm in Length

The snout portion of its skull reached up to 90 cm (35.4 inches) in length, compared to a height of 25 cm (9.8 inches) and a width of 20 cm (7.9 inches).
Additionally, a row of small, short horns lined its upper surface.

Long, Thin, and “Shallow” Teeth

When thinking of tyrannosaur teeth, they are typically thick, robust, and deeply rooted in the jaw to powerfully crush bone.
However, Qianzhousaurus possessed the contrasting characteristic of having “long, thin teeth that were shallowly rooted.”

A Slender Build and a “Specialized Diet” That Exploited a Niche

Compared to large, closely related species like Tyrannosaurus and Tarbosaurus, the body of Qianzhousaurus was very slender and relatively small, giving it a sleek appearance that at first glance resembled a juvenile of a larger species.

When first described, it was estimated to be about 6.3 meters (20.7 feet) long and weigh about 757 kg (1,670 lbs). However, a 2019 study suggested that it could have reached a maximum length of 7.5 to 9 meters (24.6 to 29.5 feet) and a weight of 1 ton (2,200 lbs).

A Diet That Avoided Competition with Large Species

Due to its long, slender snout and thin teeth, it was not suited for overpowering large prey by brute force.
Therefore, it is believed to have had a specialized diet, targeting prey such as:

• Fish, making it highly adept at a piscivorous diet similar to Spinosaurus.
• Small dinosaurs like “Corythoraptor” (oviraptorosaurs) and other small animals found in the same geological formation.

During the same period, powerful, large tyrannosaurs such as Tarbosaurus and Zhuchengtyrannus lived in Asia. It is presumed that by altering its target prey, Qianzhousaurus successfully avoided direct competition for survival with them.

An “Adult” Fossil That Unlocked Evolutionary Mysteries

Taxonomically, Qianzhousaurus forms a group called the “Alioramini tribe” alongside its close relative, “Alioramus.”
In fact, its discovery was crucial in solving a long-standing evolutionary mystery.

Overturning the Theory That “Only Juveniles Have Slender Snouts”

Until Qianzhousaurus was discovered, Alioramus was the only known tyrannosaur with a similarly long and slender snout.
Furthermore, because all Alioramus fossils found were of subadults (near-adults), there was a theory that “a long, slender snout is merely a characteristic unique to juveniles.”
However, the discovered skeleton of Qianzhousaurus was clearly an “adult,” brilliantly proving that they maintained their slender snouts even into adulthood.

A Face That Doesn’t Change?

A 2022 study on its cranial anatomy also pointed out the possibility that they did not undergo the “secondary metamorphosis”—where the face becomes more robust and blocky with growth—seen in other members of the Tyrannosauridae family.

Amidst a Tyrannosauridae family that was evolving to become massive and heavily armed, Qianzhousaurus deliberately maintained its sleek build and specialized diet.
They can be considered highly important creatures that narrate the diverse evolutionary paths of dinosaurs to us today.