Phorusrhacos longissimus Skull measures 14.1 inches. Phorusrhacos longissimus Skull is museum quality polyurethane cast. 2-part skull (separate cranium & jaw).

Phorusrhacos longissimus is an extinct genus of giant flightless terror birds that inhabited South America during the Miocene epoch.

Phorusrhacos was one of the dominant land predators in South America at the time it existed. It is thought to have lived in woodlands and grasslands.

Remains are known from several localities in the Santa Cruz Formation and Monte León Formation in Santa Cruz Province, of Argentina.

Among the bones found in the strata of the Santa Cruz Formations (now considered as mainly of mid-Miocene date) was the piece of a mandible.

Florentino Ameghino discovered it in early 1887 and the same year at first described as that of an edentate mammal which he named Phorusrhacos longissimus.

The generic name is derived from Greek (phoros), an element meaning “bearer” in word combinations, and (rhakos), “rag” or “wrinkle”, probably in reference to the wrinkled jaw surface.

When the original derivation was no longer understood, other translations were given, such as the literal translation of “Rag-Thief”, and “branch-holder” from the mistaken assumption the name had been intended to be derived from a Greek rhakis, “branch”.

The specific name means “very long” in Latin, again in reference to the lower jaws. The holotype is the mandible, specimen MLP-118 (Museo de La Plata).

In 1889 Ameghino emended the name to a more grammatically correct Phororhacos but the earlier name has priority. In 1891, it was by him recognized to be a bird.

Phorusrhacos longissimus had a skull nearly 26 in. long, stood nearly 7 ft 10 in. to 8 ft 10 in. tall, and probably weighed nearly 290 lb.