New species of unusual dinosaur found in Montana

Story by: Greg Liggett, Geologist (Paleontologist), Montana/Dakotas State Office

Dinosaurs continue to amaze researchers, even after 180 years of study. Their diversity is proving to be far more varied than just the perennial favorites like T. rex, Triceratops, and Brontosaurus.

A case in point is a group called the Alvarzsaurids (Alvarz-saurids) first described from an incomplete skeleton from Patagonia, Argentina, named Patagonykus (Pat-a-go-nykus). Then several additional species were named from Asia, and they have a generally poor record from North America.

The Alvarzsaurids were small dinosaurs, 1 to 3 meters long, but their most distinctive character is found in their hands—containing a single large, clawed finger. The bones of their arms and shoulders indicate that they had strong muscles providing for some specialized behavior, but exactly what that might have been is still a mystery. It has been suggested that they specialized in tearing apart termite mounds like a modern anteater.

Recently, bones of Alvarzsaurids were collected from the Late Cretaceous Hell Creek Formation in Montana. The Hell Creek preserves one of the few terrestrial records of the extinction of dinosaurs and the subsequent ecological recovery. Specimens have been recovered through most of the formation, with the youngest specimen being just 10 meters below the contact with the overlying Fort Union Formation, which marks the demise of dinosaurs.

Although most of the material collected are the finger claws, they are diagnostic and a new species was recently named from the material, Trierarchuncus prairiensis (Trer-arch-uncus prairie-ensis). The name comes from the Greek word for a seafaring ship’s captain, “trierarch,” and the Latin word for hook, “uncus.” So, the name translates as “Captain Hook of the prairie.” Impress your kids by teaching them about this new dinosaur!