Extinct Teratorn, Teratornithidae
April 2009

SDZ Global Logo

©San Diego Zoo Global, all rights reserved

*How Do We Know This? Like living animals, fossil remains of once-living animals are
classified and grouped according to their relationships to each other and to their ancestors.

(Campbell et al 1999)(Campbell & Tonni 1980, 1983) (Campbell & Tonni 1980) (Chatterjee et al 2007) (Howard 1963, 1972) (Miller 1909)

Describer (Date): Teratornis merriami (Miller 1909)
                           Ailornis incredibilis (Howard 1952, new combination by Campbell)
                           Cathartornis gracilis (Miller 1910)
                           Argentavis magnificens (Campbell & Toni 1980)

Kingdom: Animalia
    Phylum: Chordata
        Class: Aves
           Order: Accipitirformes - includes hawks, eagles, vultures (or Ciconiiformes - includes storks, herons);
               taxonomy at this level uncertain
                    Family: Teratornithidae (An extinct family)
                                   Genus: Teratornis
                                          Species: Teratornis merriami (Extinct Merriam's Teratorn)
                                   Genus: Aiolornis
                                          Species: Aiolornis incredibilis(Extinct Incredible Teratorn)

                                   Genus: Cathartornis
                                          Species: Cathartornis gracilis (Extinct Slender Teratorn)
                                   Genus: Argentavis
                                          Species: Argentavis magnificens (Extinct Magnificent Argentine Teratorn)                                

Taxonomic History


*How Do We Know This? Scientists use knowledge of the earth's rocks, global plate tectonic movements,
and the chemical process of fossilization to make sense of fossil distribution patterns and ancient habitats.
(Campbell & Tonni 1981) (Chatterjee et al 2007)(Palmqvist & Vizcaíno 2003) (Rhys 1980)

Prehistoric Distribution:

*How Do We Know This? Careful study of fossil bone or tooth anatomy yields much exact information
about placement and strength of muscles, tendons, ligaments, nerves, and blood vessels.
In rare cases, skin and hair impressions or actual skin or hair is preserved.
Body weight is more difficult to gauge because fat leaves no impression on the skeleton.

(Chatterjee et al 2007) (Campbell & Tonni 1983) (Campbell et al 1999)

Estimated Body Weight: T. merriami 13.7kg (30.2 lb) (Campbell & Tonni 1983). Slightly heavier than living California condors
                                      Ailornis incredibilis 23 kg (50 lb)
                                      Argentavis magnificens 70 kg (154 lb); 7 times
                                          heavier than California condor (Chatterjee et al 2007))
Estimated Wingspan: T. merriami 3.5-4m (11.5-13.1 ft)
                                   Ailornis incredibilis: 5.0-5.5 m (16.4-18 ft)
                                   Argentavis magnificens 6-8 m (19.7-26.3 ft)

General Description
Sexual Dimorphism Other Physical Characteristics

*How Do We Know This? Since direct observation of a fossil animal's behavior isn't possible, paleontologists
use comparison and contrast with living animals for guidance. Tracks can sometimes reveal further clues.

(Campbell & Tonni 1981) (Chatterjee et al 2007) (Palmqvist & Vizcaíno 2003)

Interspecies Interaction

*How Do We Know This? Clues to fossil mammals' diets come from teeth,skull shape,
from fossil dung and gut contents, from lab analysis of oxygen isotopes in bone and teeth,
and by looking at diets of similar modern animals.

(Campbell & Tonni 1981,1983) (Chatterjee et al 2007) (Hertel 1995)(Palmqvist & Vizcaíno 2003)

*How do We Know This? Isotope studies of elements present in fossil bones
in microscopic quantities give information about timing of reproductive stresses.
Clues to stages of development come from tooth replacement patterns in mammals and closure of sutures
in vertebrate skull and limb bones.

(Palmqvist & Vizcaíno 2003)

Life Stages

*How do We Know This? Abnormalities in fossil bones may show
evidence of arthritis, cancer, nutritional stress, fractures and more.

Important Web Resources (including where to view fossils in museums):

©2009 San Diego Zoo Global. Disclaimer: Although San Diego Zoo Global makes every attempt to provide accurate information, some of the facts may become outdated or replaced by new research findings. Questions and comments may be addressed to library@sandiegozoo.org.

Return to the Fact Sheet Index