Andrewsornis

Andrewsornis is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds" that lived in Oligocene Argentina. Fossils have been found in the Sarmiento Formation, and possibly the Agua de la Piedra Formation.

== Discovery and naming == Fossils of Andrewsornis were first discovered on 18 September 1923 by fossil collector John Bernard Abbott in Cabeza Blanca in the province of Chubut, Patagonia in southern Argentina. Abbott was a member of the Marshall Field Paleontological Expeditions, a series of Field Museum expeditions led by paleontologist Elmer Riggs that explored fossiliferous outcrops in Argentina and Bolivia between 1922 and 1927. The Marshall Field Paleontological Expeditions unearthed many phorusrhacid fossils, however their description was delayed by World War II. The remains found consisted of an incomplete skull, both mandibles (lower jaws), the proximal (towards body) section of the coracoid (shoulder bone), and two ungual phalanges (finger bones) from the second digit. These specimens make up the holotype (name-bearing) specimen, which was deposited at the Field Museum under specimen number FM-P13417. The strata of the Cabeza Blanca where the fossils were found corresponds to the Deseado Formation, which comes from the Deseadan SALMA (South American land mammal age) and the middle-upper Oligocene.