illustration of a large bird standing with wings extended
With a 12-foot wingspan, Teratornis merriami was the largest bird found at Tule Springs Fossil Beds National Monument.

NPS illustration by Benji Paysnoe.

Scientific Name

Teratornis merriami


A large, extinct bird of prey with a wingspan between 11-12 feet. When roosting, it stood over 2.5 feet tall and weighed roughly 33 pounds. It was about one third larger than today’s living condors.


Teratorns (family Teratornithidae) are an extinct group of birds of prey that had a similar ecological relationship to living North and South American condors (order Cathartiformes). This group first appeared in the fossil record during the Oligocene of Brazil, approximately 25 million years ago, and includes one of the largest extinct flying birds, Argentavis magnificens, which had a 20-foot wingspan. The North American teratorns first appear in the fossil record during the Pliocene (6-3 million years ago).

Distribution and Habitat

Fossils of Teratornis have been found in California, Oregon, Nevada, Arizona, and Florida in Pleistocene deposits. The teratorn is well represented from Rancho La Brea in Southern California.


The teratorn was a carnivore, feeding on large mammal carcasses and hunting smaller vertebrates.


The behavior for teratorns has been modeled after living condors and vultures, suggesting these birds flew great distances to find large mammal carcasses to scavenge on. However, teratorns were also built to actively hunt smaller game such as small mammals, reptiles, and even other birds.

Tule Springs Teratorn

The first and only fossils of Teratornis merriami at Tule Springs were collected as part of the Tule Springs Expedition of 1962-1963.


Part of a series of articles titled Prehistoric Life of Tule Springs.

Tule Springs Fossil Beds National Monument

Last updated: October 12, 2021