Photos: Newfound Dinosaur Had Tiny Arms, Just Like T. Rex

Joining the club

newfound dinosaur tiny arms

(Image credit: Copyright Jorge González and Pablo Lara)

Despite its razor-sharp teeth and impressive bite force, Tyrannosaurus rex is largely mocked for its tiny arms. Now, a new finding shows that T. rex was in good company. The discovery of a newly identified species of allosaurid, a type of medium-to-large carnivorous dinosaur, in Patagonia shows that it, too, had small arms. This suggests that evolutionary forces at the time favored small arms, explaining this display of convergent evolution — when two species develop the same characteristics independently of one another. [Read the Full Story About the Tiny-Armed Allosaurid]

Tiny-armed menace

newfound dinosaur tiny arms

(Image credit: Copyright Jorge González and Pablo Lara)

Like T. rex, Gualicho shinyae had two clawed fingers at the end of its small arms. Also like T. rex, the newfound dinosaur likely would have preyed on smaller animals, as seen here.

Patagonian find

newfound dinosaur tiny arms

(Image credit: Apesteguía, S. et al. PLOS ONE. 2016)

The researchers excavated Gualicho shinyae in Patagonia in the Huincul Formation, which is located in the Neuquén Province.

Fossil Finding

newfound dinosaur tiny arms

(Image credit: Copyright Pete Makovicky | The Field Museum)

Akiko Shinya, chief fossil preparatory at the Field Museum in Chicago, sits next to the new dinosaur (Gualicho shinyae) that is named, in part, after her. [Read the Full Story About the Tiny-Armed Allosaurid]

Truck trouble

newfound dinosaur tiny arms

(Image credit: Copyright Pete Makovicky | The Field Museum)

The new dinosaur's generic name, Gualicho, honors Gualichu, a spirit from Patagonia's Tehuelche people. The team joked that Gualichu had cursed them with bad luck, especially when their truck rolled over (everyone was OK, except for a few cuts and bruises).

Bone count

newfound dinosaur tiny arms

(Image credit: Copyright Jorge González and Pablo Lara)

A schematic showing the excavated bones of Gualicho shinyae. [Read the Full Story About the Tiny-Armed Allosaurid]

Foot bones

newfound dinosaur tiny arms

(Image credit: Apesteguía, S. et al. PLOS ONE. 2016)

The left third metatarsal (foot bone) of Gualicho shinyae, shown from different angles.

Neck bones

newfound dinosaur tiny arms

(Image credit: Apesteguía, S. et al. PLOS ONE. 2016)

The excavated caudal vertebrae (neck bones) of Gualicho shinyae. The front-most of the three discovered caudals is shown from different angles in A, B, C and D. The middle of the three caudals is shown in E, F, G and H. The lattermost of the three caudals is shown in I, J and K. [Read the Full Story About the Tiny-Armed Allosaurid]