One of the more common small birds found at Fossil Lake is a species of roller (Primobucco mcgrewi)—there are ten specimens in the Field Museum’s collection alone! This species is the oldest known member of the roller family yet found.
Strong fliers with broad bills, modern rollers take their prey on the wing, snatching insects from the air, but these birds been know to nab the occasional snake or small amphibian, too.
Specimens: Primobucco mcgrewi, (left) FMNH PA724, (right) USNM 336284
Locality: Fossil Butte Member of Green River Formation
Credit: Photo courtesy L. Grande