While larger dinosaurs are comparatively well-known, finding smaller species paints a more complete picture of life before the mass extinction

For more than a century, paleontologists have been scouring western North America’s Hell Creek Formation for new dinosaurs. The rocks preserve some of the last non-avian dinosaurs before Earth’s fifth mass extinction, including icons such as Tyrannosaurus and Triceratops. Now, experts have uncovered a new dinosaur species from the Cretaceous layers, a turkey-sized creature that was originally thought to be a young example of a different dinosaur.

Named Eoneophron infernalis and described Wednesday in PLOS One, the creature is a member of a mysterious group of roughly parrot-like dinosaurs called caenagnathids. Its discovery helps paint a fuller picture of life on Earth in the days before the infamous asteroid strike 66 million years ago.

Scientists principally identified E. infernalis by closely examining its hindlimb from the thigh bones to the base of the foot. The precise anatomical details of the fossils, as well as the dinosaur’s age at death, help differentiate it from other Cretaceous species and hint at a previously hidden array of beaked dinosaurs that lived alongside iconic Hell Creek species such as Edmontosaurus and Pachycephalosaurus.