Tyrannosaurus rex, right hand and arm of Tinker

This is a replica of the right forearm from the juvenile Tyrannosaurus rex knows as Tinker. Tinker was perhaps 75% of adult size. This specimen is of the two fingered hand, ulna and radius. The last photo on the right is a side by side comparison of the Tinker arm and an adult Trex. When Tyrannosaurus rex was first discovered, the humerus was the only element of the forelimb known. For the initial mounted skeleton as seen by the public in 1915, Osborn substituted longer, three-fingered forelimbs like those of Allosaurus. However, a year earlier, Lawrence Lambe described the short, two-fingered forelimbs of the closely related Gorgosaurus. This strongly suggested that Tyrannosaurus rex had similar forelimbs, but this hypothesis was not confirmed until the first complete Tyrannosaurus rex forelimbs were identified in 1989, belonging to MOR 555 (the "Wankel rex"). The remains of Sue also include complete forelimbs. Tyrannosaurus rex arms are very small relative to overall body size, meas