Britannica
Sources used in this answer
Why did early tyrannosaurs such as Guanlong retain three fingers?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
tyrannosaur
The fossilized remains of Sue, the most complete Tyrannosaurus rex skeleton in the world, on display at the Field Museum of Natural History, Chicago.
Early tyrannosaurs such as Guanlong retained three fingers because they were primitive members of the tyrannosaur group. While later, more derived tyrannosaurs evolved to have their hands reduced to only two digits, these earlier forms—including Guanlong, Dilong, and Eotyrannus—are considered so primitive that they still possessed the ancestral three-fingered hand structure.12