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Extinct Teratorn (Family Teratornithidae) Fact Sheet: Physical Characteristics

Extinct Teratorn (Teratornis merriami, Aiolornis incredibilis, Cathartornis gracilis, Argentavis magnificens) Family Teratornithidae

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 remains.
Body weight is more difficult to gauge because fat leaves no impression on the skeleton.

Physical Characteristics

AttributeTeratornis merriamiAilornis incredibilisArgentavis magnificens
Estimated Body Weight
13.7 kg (30.2 lb) (Campbell & Tonni 1983)
Slightly heavier than living California Condor.
23 kg (50 lb) 70 kg (154 lb); 7 times heavier than California Condor (Chatterjee et al 2007)
Estimated Wingpsan
3.5-4 m (11.5-13.1 ft) 5.0-5.5 m (16.4-18 ft) 6-8 m (19.7-26.3 ft)

General Appearance

General Description

  • Large soaring predatory birds with stout legs, long toes, with the last digits moderately curved and blunt (not used for holding prey as in hawks or eagles).
  • Pelvis resembles a stork's; they were adept walkers on the ground, but not good runners. (Campbell & Tonni 1983)

Sexual Dimorphism

  • None known

Other Physical and Physiological Characteristics

  • Wing bones have features of condors and also pelicans and Bald Eagles (Campbell & Tonni 1983) (Hertel 1995).
  • Sutures between some skull bones are not tightly fused; this may help teratorns swallow large and struggling prey (Campbell & Tonni 1981).
    • This is one reason paleontologists do not think they had scavenging habits.
  • A sharp hooked bill known for T. merriami; skull of Argentavis not known.

Page Citations

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

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